Distortions of perception · perceptual distortion. A perceptual distortion involves an inconsistency, or ‘mismatch’, between a perceptual experience and physical reality. Visual

CHAPTER

8 Distortions of perception

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KEY KNOWLEDGE

■ the fallibility of visual and gustatory perceptions, demonstrated by visual illusions and the judgement of � avours (in� uence of perceptual set, colour intensity and texture)

■ distortions of perception of taste and vision in healthy, intact brains as providing insight into brain function related to perception, illustrated by synaesthesia

Visual illusions 336

Judgement of � avours 341

Synaesthesia 345

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Judgement of � avours

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Synaesthesia

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PROOFS

PROOFS

PROOFSthe fallibility of visual and gustatory

PROOFSthe fallibility of visual and gustatory perceptions, demonstrated by visual illusions

PROOFSperceptions, demonstrated by visual illusions and the judgement of � avours (in� uence of

PROOFSand the judgement of � avours (in� uence of perceptual set, colour intensity and texture)

PROOFSperceptual set, colour intensity and texture)

distortions of perception of taste and vision in

PROOFSdistortions of perception of taste and vision in healthy, intact brains as providing insight into

PROOFShealthy, intact brains as providing insight into brain function related to perception, illustrated PROOFS

brain function related to perception, illustrated by synaesthesiaPROOFS

by synaesthesia


CHAPTER 8 Distortions of perception 335

Perception occurs when sensory information reaching the brain is meaningfully interpreted. What we see, taste, hear, smell, and so on, is the result of brain activities that construct reliable representations of reality. This allows us to adapt to the environment and make sense of a constantly changing world.

Most of the time, our perception of the world closely matches the physical environment around us. However, this does not mean that perception is always error-free or perfect. We sometimes make mistakes and experience a perceptual distortion.

A perceptual distortion involves an inconsistency, or ‘mismatch’, between a perceptual experience and physical reality. Visual illusions demonstrate cases in which reality is misperceived for no immediately apparent reason. For example, the horizontal lines in � gure 8.1 below are parallel. You can con� rm this with a ruler yet, whenever you look at the pattern, it is impossible to perceive the horizontal lines as parallel.

FIGURE 8.1 Are the horizontal lines parallel or do they slope?

Similarly, consider the naturally occurring ‘real life’ moon illusion, whereby the moon appears larger when it is low in the sky near the horizon than when it is high in the sky. The moon does not actually change in size. Yet when the moon illusion is apparent, we cannot avoid perceiving the moon as bigger.

FIGURE 8.2 Why does the moon look so much larger when on the horizon than when it is high in the sky? (See box 8.1.)

Perceptual distortions occur with all other senses too. For example, some people can perceive taste in something that has no chemical basis for what is tasted and some can hear things that may not exist in reality. Pain can also persist long after the injury that caused it has healed. For example, consider people with an amputated limb who continue to perceive chronic pain after the loss of an arm or leg (see pages 000–00).

Consider also examples of when you perceive movement that is not real. Have you ever noticed how the moon appears to be moving across the sky as clouds pass in front of it on a cloudy, windy night? A similar effect can occur when you are sitting in a car at a stoplight and the vehicle next to you starts to move forward. For a moment you may feel that you are moving backwards. This is despite the fact that your vehicle has not actually moved and the adjacent vehicle is the source of real movement.

In this chapter we examine the fallibility of perception demonstrated in visual perception by visual illusions and in taste perception by the judgement of � avours. We also consider a speci� c type of distortion involving interaction of the senses in synaesthesia — when stimulation of one sense produces experiences in another sense.

UNCORRECTED in which reality is misperceived for no immediately

UNCORRECTED in which reality is misperceived for no immediately apparent reason. For example, the horizontal lines

UNCORRECTED apparent reason. For example, the horizontal lines in � gure 8.1 below are parallel. You can con� rm this

UNCORRECTED in � gure 8.1 below are parallel. You can con� rm this with a ruler yet, whenever you look at the pattern, it is

UNCORRECTED with a ruler yet, whenever you look at the pattern, it is impossible to perceive the horizontal lines as parallel.

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UNIT 2 How do external factors in� uence behaviour and mental processes?336


principles and factors such as learning (past experience) and context on the formation of our perceptions.

Two of the most widely studied illusions in psychology are the Müller-Lyer and Ames room illusions.

Müller-Lyer illusionAre the vertical lines in � gure 8.4 the same length? Since illusions are being examined in this section, you probably realise that they are the same length and therefore answered ‘Yes’. But do they appear to be the same length?

The answer is ‘No’. Measure the two vertical lines to con� rm that they are identical in length. Look again at the two lines. Despite the fact that you know they are of equal length, they still do not look equal. Your distorted perception has been caused by the con� guration of lines that make up the Müller-Lyer illusion — an illusion that has attracted a great deal of research by psychologists.

WeblinkVideos on visual illusions

WeblinkVisual illusion site

FIGURE 8.3 Some of the more widely studied visual illusions

Zöllner illusion: The vertical lines are all parallel but do not look parallel because of the changing direction of the small diagonal lines crossing them.

Fraser spiral: Although we perceive a spiral, this is actually a picture of a series of concentric rings.

Orbison illusion: The smaller inner circle appears misshapen when placed in the ‘spokes’ of the larger circle.

Horizontal–vertical illusion: Although the two lines are equal in length, the vertical line appears to be longer.

Hering illusion: All four horizontal lines are parallel although the middle two appear to ‘bow’ around the central point where all the diagonal lines meet.

Poggendorf illusion: The diagonal line running from bottom left to top right appears to exit the vertical bar too high. A ruler placed on the line can confirm that the line is perfectly straight.

VISUAL ILLUSIONSA visual illusion is a consistent misinterpretation (distortion or mistake) of real sensory information. It is an experience in which there is a mismatch between our perception and what we understand as physical reality. Every time we view the same sensory information, we have the same illusory experience.

Psychologists have identi� ed over 200 visual illusions, some of which are shown in � gure 8.3. Generally, the illusory effects are unavoidable. Even when we know that we are looking at an illusion and have an understanding of why the illusion occurs, we continue to see the illusion as powerfully as when we � rst saw it.

Psychologists have enhanced their understanding of visual perception by examining the conditions under which it fails. For instance, visual illusions demonstrate the important role our brain plays in constructing our view of the world. They also demonstrate the effect of perceptual

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Zöllner illusion:

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Zöllner illusion: but do not look parallel because of the changing

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but do not look parallel because of the changing direction of the small diagonal lines crossing them.

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appear

PROOFSappear

The answer is ‘No’. Measure the two vertical

PROOFSThe answer is ‘No’. Measure the two vertical lines to con� rm that they are identical in length.

PROOFSlines to con� rm that they are identical in length. Look again at the two lines. Despite the fact

PROOFSLook again at the two lines. Despite the fact that you know they are of equal length, they

PROOFSthat you know they are of equal length, they still do not look equal. Your distorted perception

PROOFSstill do not look equal. Your distorted perception has been caused by the con� guration of lines

PROOFShas been caused by the con� guration of lines that make up the Müller-Lyer illusion — an

PROOFSthat make up the Müller-Lyer illusion — an illusion that has attracted a great deal of research

PROOFS

illusion that has attracted a great deal of research

CHAPTER 8 Distortions of perception


337

Named after Franz Müller-Lyer (1857–1916) who originally described it in 1889, the Müller-Lyer illusion is a visual illusion in which one of two lines of equal length, each of which has opposite shaped ends, is incorrectly perceived as being longer than the other. As shown in � gure 8.4, the line with the ‘feather tail’ at each end (b) is perceived as being longer than the line with the ‘arrowhead’ at each end (a).

Psychologists have proposed a variety of explanations for the Müller-Lyer illusion. We consider explanations from biological, psychological and social perspectives.

Biological perspectiveExplanations from the biological perspective emphasise the role played by our eyes, brains and/or nervous system when we view the illusion. One of the earliest biological theories proposed that the Müller-Lyer illusion was caused by the eye itself and explained the illusion in terms of eye movements and a failure of the brain to properly process differing information about eye movements.

Eye movement theory proposes that the arrowheaded and feather-tailed lines require different types and/or amounts of eye movements. Because the entire feather-tailed line in the illusion is longer, it lengthens the eye movements required to view the line. Therefore we perceive this line as longer. Another version of the eye movement theory is that we perceive the feather-tailed line as longer because it takes more eye movements to view a line with inward pointing arrows than it does a line with outward pointing arrows.

Despite these different interpretations of eye movements, eye movement theory was rejected by psychologists when researchers found that the illusion

Practical activity — measuring the Müller-Lyer illusion

FIGURE 8.4 The standard Müller-Lyer illusion

(d)(c)(b)(a)

continues to be seen even when there is no eye movement at all.

More recent biological theories have been based on neuroimaging studies; for example, scanning the brain while participants with or without brain damage are looking at the illusion. These studies have identi� ed speci� c brain areas that are active and inactive when we view the illusion, but they have not been able to satisfactorily explain why we perceive the illusory effects. It may be the case that we have an inborn tendency to misperceive simple geometric patterns when they are viewed in a two-dimensional form.

FIGURE 8.5 One biological explanation of the Müller-Lyer illusion is based on eye movements.

Psychological perspectiveSome explanations from a psychological perspective emphasise the role of learning and past experience. For example, it has been proposed that we experience the illusion because it contradicts what we have learned throughout life about physical reality. Therefore, we cannot make sense of the illusion whenever we view it, even after the illusion is explained to us.

One learning-based explanation of the illusion that created a lot of interest is known as the carpentered world hypothesis. This explanation proposes that the illusion occurs because of its similarity to familiar architectural features in the real three-dimensional world we experience as part of everyday life (as shown in � gures 8.4(c) and (d) below).

UNCORRECTED perceive the feather-tailed line as longer because it

UNCORRECTED perceive the feather-tailed line as longer because it takes more eye movements to view a line with inward

UNCORRECTED takes more eye movements to view a line with inward pointing arrows than it does a line with outward

UNCORRECTED pointing arrows than it does a line with outward

Despite these different interpretations of eye

UNCORRECTED Despite these different interpretations of eye

movements, eye movement theory was rejected by

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movements, eye movement theory was rejected by psychologists when researchers found that the illusion

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psychologists when researchers found that the illusion

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explained to us.

UNCORRECTED explained to us.PAGE Psychological perspective

PAGE Psychological perspectiveSome explanations from a psychological perspective

PAGE Some explanations from a psychological perspective emphasise the role of learning and past experience.

PAGE emphasise the role of learning and past experience. For example, it has been proposed that we experience

PAGE For example, it has been proposed that we experience the illusion because it contradicts what we have

PAGE the illusion because it contradicts what we have learned throughout life about physical reality. PAGE learned throughout life about physical reality. Therefore, we cannot make sense of the illusion PAGE Therefore, we cannot make sense of the illusion whenever we view it, even after the illusion is PAGE

whenever we view it, even after the illusion is

PROOFSwhen they are viewed in a two-dimensional form.

PROOFSwhen they are viewed in a two-dimensional form.

PROOFS

PROOFS

PROOFSOne biological explanation of the

PROOFSOne biological explanation of the

Müller-Lyer illusion is based on eye movements.

PROOFSMüller-Lyer illusion is based on eye movements.

PROOFS

Psychological perspectivePROOFS

Psychological perspective



In our three-dimensional world, we have grown accustomed to seeing corners everywhere and often use these and other angles and lines to judge depth and distance. As a consequence of this experience, the arrowheaded line looks like the nearer, outside, vertical corner and roo� ine of a room or building, whereas the feather-tailed line looks like the farthest, inside corner (including ceiling and � oor) of a room. Consequently, the two vertical lines appear to be at different distances from the observer — the feather-tailed line appears further away. Our brain overrides information from the retinal images showing the two vertical lines as equal in length. Therefore, the line that appears further away (feather-tailed line) is perceived as longer.

Other psychological explanations of the illusion emphasise how we take in and process visual information in order to perceive the illusion. For example, it has been proposed that the perceptual error we make with the illusion may be due to using inappropriate mental strategies when interpreting the incoming visual information. For example, we may incorrectly use the principle of size constancy. This would lead us to make an interpretation that when two lines appear to be at different distances, and cast retinal images of equal size, then the line which appears further away (the feather-tailed line) must be longer. The incorrect interpretation results in the illusion.

In this way, the Müller-Lyer illusion can be said to result from inappropriate use of perceptual processes involved in maintaining size constancy, when we know from depth cues (same-sized retinal images) and past experience, that objects appearing to be at different distances can be of identical size or length. Furthermore, our perception of the illusion suggests that we sometimes don’t interpret a retinal

FIGURE 8.6 Variations of the Müller-Lyer illusion. These � gures work just as well to produce the Müller-Lyer illusion without the depth cues said to cause the illusion in the original vertical � gure.

image as being what it really is, but rather what it represents.

Critics of this misapplication of size constancy theory have questioned why the illusion works equally well when the two lines are horizontal rather than vertical, as shown in � gure 8.6. Furthermore, psychologists have produced other variations of the Müller-Lyer illusion which use different shapes on the ends, which are also shown in � gure 8.6. These variations of the illusion are equally effective in producing the illusion as the original � gures.

Social perspectiveResearch studies conducted from this perspective have focused on the role of social factors, particularly cultural in� uences on the perception of the Müller-Lyer illusion. These studies have also provided evidence for the role of learning and past experience in perceiving the illusion. For example, in some cultures, people have spent most of their lives in ‘non-carpentered’ worlds (see � gure 8.7(b)).

One such group are Zulus who live in tribal communities within remote areas of Africa. These Zulus live in circular houses with roundish doors and domed roofs — without all the familiar angles, corners and edges of our Western three-dimensional world. When shown the Müller-Lyer illusion, these Zulus are more likely to view the lines in their actual two-dimensional forms and therefore perceive the lines as equal in length. They have only limited, if any, experience of angles and corners in their three-dimensional worlds and are consequently less likely to perceive the illusion.

A socio-cultural study has also been conducted to compare responses to the illusion by white American children and Zambian children in Africa. The study included a comparison of Zambian

UNCORRECTED processes involved in maintaining size constancy,

UNCORRECTED processes involved in maintaining size constancy, when we know from depth cues (same-sized retinal

UNCORRECTED when we know from depth cues (same-sized retinal images) and past experience, that objects appearing

UNCORRECTED images) and past experience, that objects appearing to be at different distances can be of identical size or

UNCORRECTED to be at different distances can be of identical size or length. Furthermore, our perception of the illusion

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PAGE One such group are Zulus who live in tribal

PAGE One such group are Zulus who live in tribal communities within remote areas of Africa. These

PAGE communities within remote areas of Africa. These Zulus live in circular houses with roundish doors

PAGE Zulus live in circular houses with roundish doors and domed roofs — without all the familiar angles,

PAGE and domed roofs — without all the familiar angles, corners and edges of our Western three-dimensional

PAGE corners and edges of our Western three-dimensional world. When shown the Müller-Lyer illusion, these

PAGE world. When shown the Müller-Lyer illusion, these Zulus are more likely to view the lines in their actual

PAGE Zulus are more likely to view the lines in their actual two-dimensional forms and therefore perceive the PAGE two-dimensional forms and therefore perceive the lines as equal in length. They have only limited, if PAGE

lines as equal in length. They have only limited, if

PROOFSResearch studies conducted from this perspective

PROOFSResearch studies conducted from this perspective have focused on the role of social factors, particularly

PROOFShave focused on the role of social factors, particularly cultural in� uences on the perception of the Müller-

PROOFScultural in� uences on the perception of the Müller-Lyer illusion. These studies have also provided

PROOFSLyer illusion. These studies have also provided evidence for the role of learning and past experience

PROOFSevidence for the role of learning and past experience in perceiving the illusion. For example, in some

PROOFSin perceiving the illusion. For example, in some cultures, people have spent most of their lives in

PROOFScultures, people have spent most of their lives in ‘non-carpentered’ worlds (see � gure 8.7(b)).PROOFS

‘non-carpentered’ worlds (see � gure 8.7(b)).One such group are Zulus who live in tribal PROOFS

One such group are Zulus who live in tribal communities within remote areas of Africa. These PROOFS

communities within remote areas of Africa. These



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The Ames room illusion involves a trapezium-shaped room that is longer and higher on one side than the other. When viewed through a peephole at the front of the room using only one eye, the room appears rectangular. The room’s unusual shape and being restricted to the use of monocular vision to view it provides the basis for the illusion.

Although other items in the room such as windows, clocks and furniture may add to the impact of the illusion, these items are not essential for the illusion to occur. The illusion is named after American psychologist Adelbert Ames (1880–1955) who intentionally designed the room to distort visual perception, particularly the size of objects in the room.

The Ames room appears to be a normal rectangular room when viewed through a peephole located in a central position on the front wall. The back wall looks parallel to the front wall and the two back corners therefore appear to be exactly the same distance from the observer.

A crucial aspect of the illusion is that the back wall is actually slanted away from the observer (from right to left). This results in the far left corner being double the distance of the right corner from the peephole. When observing a person standing in the right corner at the back of the room, the image of that person which is cast on the retina is larger because the person is twice as close to the observer (compared to a person standing in the back left corner). In addition, the ceiling slopes upwards from the right upper corner to the left upper corner of the room. This increases the height of the ceiling from right to left, which also helps ensure the illusion occurs.

As a result of these deliberately constructed ‘deceptions’, Ames was able to make people appear small or large, depending on where they stood in the room. When we view the inside of the room through the peephole, our past experience with rectangular rooms leads us to expect that the people in the room are all the same distance away from us. However, in this situation, one person casts a smaller or larger retinal image than the other, so their sizes are perceived as different.

According to apparent distance theory, when two retinal images are the same size, but one image appears to be at a greater distance, then the one that appears further away will be interpreted as bigger or larger.

In the Ames room, the perceived rectangular shape of the room is consistent with the retinal image, but not consistent with the room’s real shape. The back corners on either side of the room actually produce equal-sized retinal images because the vertical length of the further left corner is double the length (but twice the distance from the observer) of the nearer right corner. Therefore the visual angle is the same for both corners from the observer’s view. Because

children living in tribal communities in rural areas and Zambian children living in urban areas such as towns or cities. The results showed that the white American children were more likely to perceive the illusion than were the Zambian children living in urban areas. Furthermore, the Zambian children living in urban areas were more likely to perceive the illusion than the rural Zambian children. Since the rural Zambian children were much less exposed to rectangular structures, it seems that experience associated with the environment in which we grow up is a relevant factor in perceiving the Müller-Lyer illusion (Segall et al., 1990; Segall, Campbell & Herskovits, 1966).

FIGURE 8.7 (a) Carpentered and (b) non-carpentered worlds

(b)(a)

In sum, each of the different perspectives offers useful insights into factors that may in� uence our perception of the Müller-Lyer illusion. Psychologists from each of these perspectives have constructed and tested many hypotheses through experimental research. Many have also developed theories by drawing on the theories and research � ndings of other perspectives. However, psychologists from all perspectives mostly agree that there is not yet any single explanation of the illusion that is entirely satisfactory.

Ames room illusionExamine the photograph in � gure 8.8. The person on the right appears to be much bigger than the person on the left. However, both people are actually of normal size. This illusion involves people appearing smaller or larger, depending on where they are standing. It is based on the unusual construction of the room, particularly the shape of the back wall.

Explanation of Müller-Lyer and Ames illusions

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useful insights into factors that may in� uence our perception of the Müller-Lyer illusion. Psychologists

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perception of the Müller-Lyer illusion. Psychologists from each of these perspectives have constructed and

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research. Many have also developed theories by drawing on the theories and research � ndings of

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drawing on the theories and research � ndings of other perspectives. However, psychologists from all

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other perspectives. However, psychologists from all

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PAGE A crucial aspect of the illusion is that the back wall

PAGE A crucial aspect of the illusion is that the back wall is actually slanted away from the observer (from right

PAGE is actually slanted away from the observer (from right to left). This results in the far left corner being double

PAGE to left). This results in the far left corner being double the distance of the right corner from the peephole.

PAGE the distance of the right corner from the peephole. When observing a person standing in the right corner

PAGE When observing a person standing in the right corner at the back of the room, the image of that person

PAGE at the back of the room, the image of that person which is cast on the retina is larger because the PAGE which is cast on the retina is larger because the person is twice as close to the observer (compared to PAGE person is twice as close to the observer (compared to a person standing in the back left corner). In addition, PAGE

a person standing in the back left corner). In addition,

PROOFSAmerican psychologist Adelbert Ames (1880–1955)

PROOFSAmerican psychologist Adelbert Ames (1880–1955) who intentionally designed the room to distort

PROOFSwho intentionally designed the room to distort visual perception, particularly the size of objects in

PROOFSvisual perception, particularly the size of objects in

The Ames room appears to be a normal rectangular

PROOFSThe Ames room appears to be a normal rectangular

room when viewed through a peephole located in a

PROOFSroom when viewed through a peephole located in a central position on the front wall. The back wall looks

PROOFScentral position on the front wall. The back wall looks parallel to the front wall and the two back corners

PROOFSparallel to the front wall and the two back corners therefore appear to be exactly the same distance from

PROOFStherefore appear to be exactly the same distance from

A crucial aspect of the illusion is that the back wall PROOFS

A crucial aspect of the illusion is that the back wall is actually slanted away from the observer (from right PROOFS

is actually slanted away from the observer (from right



the observer does not have the depth cues available to ‘work out’ the real difference in distance between the two corners, the equal-sized retinal images of the corners are interpreted as equal in size. This produces an illusion of a rectangular room.

The Ames room illusion also illustrates our inability to maintain size constancy when our use of depth cues is restricted or the depth cues are misleading. Size

FIGURE 8.8 There is a distortion of the sizes of objects within the Ames room. A crucial feature of the room that creates the illusory effect is the back wall, which is actually slanting away from the observer, but appears to be a normal rear wall of a rectangular room.

2.3 metres

3 metres

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Peephole

constancy fails because the retinal information — the changing sizes of the people as they cross the � oor — cannot be corrected due to the lack of accurate depth information. The illusion is so strong that a person observed walking from the right corner to the left corner is perceived as ‘shrinking’, even though the observer knows that this is not possible in the real world.

Video on Ames room illusion 2 m 54 s

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341

BOX 8.1

The moon illusion

Unlike the Müller-Lyer and Ames room illusions, which are arti�cially created, the moon illusion is a naturally occurring illusion. The illusion occurs when the moon appears considerably larger when near the horizon than when it is high up in the sky, even though the retinal image is equal in both situations, and the moon does not actually change its size as it moves across the sky. The illusion is more obvious with a full moon. It has intrigued people for many centuries and various theories have been proposed to explain it.

The most widely accepted explanation is in terms of apparent distance theory (which is also used to explain the Ames room illusion). This theory is based on the results of research conducted by American psychologists Lloyd Kaufman and Irvin Rock.

Kaufman and Rock (1962) proposed that viewing the moon over a visible stretch of terrain such as a landscape makes it appear further away. They found that when research participants viewed the moon at the horizon over a visible surface (e.g., trees and buildings), it appeared on average 1.3 times larger than the moon seen at its highest point in the sky (its zenith). However,

when the terrain was kept out of vision by observing the moon through a hole in a sheet of cardboard, no difference in size between the horizon and zenith moons was reported.

Kaufman and Rock concluded that the terrain offers many depth and distance cues that provide ‘evidence’ to allow us to perceive the moon as more distant, whereas the sky offers no depth and distance cues, so we misperceive distance and underestimate the moon’s size.

Not all psychologists agree with this explanation. For example, Coren and Aks (1990) have found that people sometimes perceive the horizon moon as closer, not more distant; Reed and Krupinski (1992) have found that the illusory effect cannot be created when the visual stimulus is a star rather than the moon; and Suzuki (1991) found that the illusion can still occur even when the moon is projected at different points in the sky without the presence of depth and distance cues, as in the total darkness of an indoor planetarium. In sum, a completely satisfactory explanation of the moon illusion has yet to be proposed (Kassin, 1995).

LEARNING ACTIVITY 8.1

Review questions

1 Why are visual illusions often referred to as ‘distortions of visual perception’?

2 In what way can the study of visual illusions enhance understanding of visual perception?

3 In point form, outline an explanation of the Müller-Lyer illusion that you �nd the most reasonable and convincing.

4 (a) Brie�y describe the Ames room illusion.(b) If you watch a person walk from the back right-

hand corner of the Ames room to the back left-hand corner of the Ames room, they are likely to appear to shrink. Explain why you would perceive the person to be shrinking.

(c) Why is the observer’s view restricted to using monocular cues?

(d) What is a possible explanation of the Ames room illusion?

5 Find an example of a visual illusion that you �nd intriguing.(a) Make a copy of the illusion (or provide information

on where to �nd it).(b) Outline the illusory effect.(c) What is a possible explanation of the

illusory effect?

JUDGEMENT OF FLAVOURSThe perception of taste is a relatively limited experience that is based on �ve basic taste qualities. When we taste, what we actually perceive is the combined input from different senses, not just taste and other oral sensations. This overall experience results in �avour. Flavour is not in the food (or drink) — it is created from the food by the brain. Flavour tells us whether a food is delicious, good, unpleasant or even disgusting.

Flavour is a perceptual experience produced by a combination of taste and other sensations. A crucial component is smell. In addition, there is sensory information from receptors in papillae that detect temperature (e.g. hot or cold porridge), pain (e.g. too much chilli or spiciness) and the tactile sensation of texture (e.g. chunky or smooth peanut butter).

Many psychologists have broadened the concept of �avour to include auditory sensations, such as the sounds heard when food is bitten or chewed, especially noisy foods such as carrots, celery and potato crisps, and visual sensations involving what a food or drink looks like and how it is presented (Spence, 2014; Spence, et. al, 2010).

The pleasure of food and beverages is critically dependent on all the sensory components being right. The ideal lasagne, salad, milkshake or mocktail is a perfect mix of all the sensory inputs. This also means that the taste of food can, for example, be ruined simply if

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UNCORRECTED e visual illusions often referred to as

UNCORRECTED e visual illusions often referred to as

In what way can the study of visual illusions enhance

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In what way can the study of visual illusions enhance ception?

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ception?In point form, outline an explanation of the Müller

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In point form, outline an explanation of the MüllerLyer illusion that you �nd the most reasonable and

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Lyer illusion that you �nd the most reasonable and

Brie�y describe the Ames r

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Brie�y describe the Ames room illusion.

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oom illusion.If you watch a person walk fr

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If you watch a person walk frhand corner of the Ames room to the back left-

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hand corner of the Ames room to the back left-hand corner of the Ames room, they are likely to

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hand corner of the Ames room, they are likely to appear to shrink. Explain why you would perceive

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appear to shrink. Explain why you would perceive the person to be shrinking.

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the person to be shrinking.

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(c) UNCORRECTED

(c) Why is the observer’UNCORRECTED

Why is the observer’monocular cues?UNCORRECTED

monocular cues?What is a possible explanation of the Ames UNCORRECTED

What is a possible explanation of the Ames

JUDG

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PAGE

PAGE indoor planetarium. In sum, a completely satisfactory

PAGE indoor planetarium. In sum, a completely satisfactory explanation of the moon illusion has yet to be proposed

PAGE explanation of the moon illusion has yet to be proposed (Kassin, 1995).

PAGE (Kassin, 1995).PROOFSNot all psychologists agree with this explanation.

PROOFSNot all psychologists agree with this explanation. For example, Coren and Aks (1990) have found that

PROOFSFor example, Coren and Aks (1990) have found that people sometimes perceive the horizon moon as

PROOFSpeople sometimes perceive the horizon moon as closer, not more distant; Reed and Krupinski (1992)

PROOFScloser, not more distant; Reed and Krupinski (1992) have found that the illusory effect cannot be created

PROOFShave found that the illusory effect cannot be created when the visual stimulus is a star rather than the

PROOFSwhen the visual stimulus is a star rather than the moon; and Suzuki (1991) found that the illusion

PROOFSmoon; and Suzuki (1991) found that the illusion can still occur even when the moon is projected at

PROOFScan still occur even when the moon is projected at different points in the sky without the presence of

PROOFS

different points in the sky without the presence of depth and distance cues, as in the total darkness of an PROOFS

depth and distance cues, as in the total darkness of an indoor planetarium. In sum, a completely satisfactory PROOFS

indoor planetarium. In sum, a completely satisfactory explanation of the moon illusion has yet to be proposed PROOFS

explanation of the moon illusion has yet to be proposed



it has an inappropriate colour or is not crunchy enough. In such cases, the in� uence of one type of sensory input may dominate or override other sensory input.

Given the multi-sensory nature of � avour, its perception is in� uenced by numerous factors. These include perceptual set, colour intensity and texture. Food producers and retailers recognise these in� uences when manufacturing and marketing their foods and beverages. Millions are spent on packaging and appearance to in� uence our choices, in our homes as well as in supermarkets, restaurants, school canteens and wherever else we may purchase food.

Perceptual setThe � avour we experience is in� uenced by expectations based on preconceived ideas about how foods (and drinks) should taste. These form through past experience. It is not even essential to have actually tasted something to have an expectation of � avour. For example, the mere thought of eating a live cockroach is likely to disgust you without knowing what it actually tastes like. Your expectation is enough to produce disgust.

FIGURE 8.9 <Caption TBA> WeblinkFlavour perception

One of the most signi� cant in� uences on � avour judgement is our expectation of how food should look. Colour tends to be the single most important visual cue when it comes to our expectation about the likely taste and � avour of food (Spence, 2015). We start to associate speci� c colours with various types of foods and drinks during childhood and link them to certain tastes and � avors throughout life. For example, we expect yellow pudding to have a banana or lemon � avour and brown pudding to have a chocolate � avour. We also use colour to determine the ripeness and/or freshness of fruits, vegetables, meats, � sh, dairy products and even lollies. If colour does not match our expectations, we may perceive the � avour of any one of these foods differently.

When the colour of a food or drink is different to what we expect, our brain can interpret that it tastes different too. Researchers have used colour to manipulate expectations and distort � avour judgements of participants in numerous studies.

One of the best known demonstrations of this effect was reported by the American food researcher John Wheatley (1973). A group of people were served a meal of steak, French fries and peas under lighting conditions that masked the true colour of each food. All thought the meal was � ne until the lighting was changed. Halfway through the meal, normal lighting was restored and it became apparent to the diners that they were eating blue steak, green fries and red peas. Upon realising this, many lost their appetite and some became ill.

According to Wheatley, the mere sight of the unnaturally coloured food was suf� cient to induce nausea. In particular, the colour blue is often associated with spoiled, mouldy meat, creating an expectation that food of this colour won’t taste very good and/or is likely to be off and cause some kind of food poisoning (Zampini & Spence, 2012).

FIGURE 8.10 We have expectations of how food should look and this perceptual set can in� uence our � avour judgement of the food.

Researchers have also investigated the effect of perceptual set on our judgement of drink � avours. In one of the best-known studies, the colour of a cherry-� avoured drink was manipulated. The addition of an odourless orange or green food-colouring solution that was actually neutral in � avour led participants to incorrectly identify the � avour. For example, when the red, cherry-� avoured drink was changed to an orange colour, 41% of the participants reported that the drink tasted of orange compared to 0% when the drink’s colour had not been changed. Colouring the same drink green led to 37% lime-� avoured responses (DuBose, Cardello & Maller, 1980).

Even expert � avour tasters can be misled when their � avour expectations are manipulated. For example, some professional wine tasters and wine makers have been found to describe a white wine that had been arti� cially coloured red as having key characteristics of red wine. One explanation of wine experts being deceived in this way is that their expectations of the taste, aroma and � avour characteristics are much more strongly associated with a particular wine colour than in the non-expert (Spence, 2010).

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Weblink

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WeblinkFlavour perception

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Flavour perception

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One of the most signi� cant in� uences on � avour

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One of the most signi� cant in� uences on � avour judgement is our expectation of how food should

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judgement is our expectation of how food should look. Colour tends to be the single most important

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look. Colour tends to be the single most important visual cue when it comes to our expectation about

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visual cue when it comes to our expectation about the likely taste and � avour of food (Spence, 2015). We

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the likely taste and � avour of food (Spence, 2015). We start to associate speci� c colours with various types of

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start to associate speci� c colours with various types of foods and drinks during childhood and link them to

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foods and drinks during childhood and link them to certain tastes and � avors throughout life. For example,

UNCORRECTED

certain tastes and � avors throughout life. For example, we expect yellow pudding to have a banana or UNCORRECTED

we expect yellow pudding to have a banana or lemon � avour and brown pudding to have a chocolate UNCORRECTED

lemon � avour and brown pudding to have a chocolate � avour. We also use colour to determine the ripeness UNCORRECTED

� avour. We also use colour to determine the ripeness UNCORRECTED

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PAGE PROOFS

unnaturally coloured food was suf� cient to induce

PROOFSunnaturally coloured food was suf� cient to induce nausea. In particular, the colour blue is often

PROOFSnausea. In particular, the colour blue is often associated with spoiled, mouldy meat, creating an

PROOFSassociated with spoiled, mouldy meat, creating an expectation that food of this colour won’t taste very

PROOFSexpectation that food of this colour won’t taste very good and/or is likely to be off and cause some kind of

PROOFSgood and/or is likely to be off and cause some kind of food poisoning (Zampini & Spence, 2012).

PROOFSfood poisoning (Zampini & Spence, 2012).

PROOFS

PROOFS

PROOFS



343

Colour intensity Colour tends to dominate over other sensory information when it comes to in� uencing our expectations about taste and � avour of food. In addition, changing the intensity of a colour can exert a sometimes dramatic impact on our expectations, and hence on the taste and � avour experiences. For example, a brighter or richer coloured food item can seem to taste different to a blander coloured one, even when there is no change in the ingredients that make up the � avour (Spence, 2015).

Regardless of age or culture, there tends to be an expectation that more intensely coloured foods are likely to be more intensely � avoured. Research studies have found that simply adding more colouring to a food can lead participants to rate the taste and/or � avour as more intense. Most studies have been conducted with beverages. This is mainly because it is easier to manipulate the level of colour in solutions (Delwiche, 2012; Watson, 2013).

In one study, researchers investigated the in� uence of varying the intensity of colour on ratings of sweetness intensity. The participants were given two glasses of orange juice to compare and to rate in terms of their sweetness. The juices were lighter and darker shades of orange. The tasters rated the orange juice with the more intense, darker shade as being much sweeter. When later given two glasses of orange juice that had the same colour intensity but differing degrees of sweetness, most tasters did not report a different in taste. Then, when asked to taste orange juice in which a � avourless green colour tinge was added, a signi� cant number of participants reported the presence of sourness. In a similar study, participants who drank strawberry- and cherry-� avoured juices reported that drinks with more red colour tasted stronger and had ‘more’ and ‘truer’ strawberry and cherry � avours. The effect was stronger among older than younger tasters (Fernández-Vázquez et al., 2014).

Studies that have manipulated the colour intensity of food have also reported distorted perceptions of � avour. As with drink studies, the colour is intensi� ed using a food dye but there is no actual change in � avour. The results of food studies also show that overall � avour intensity is in� uenced by the amount of colouring that is added — the more intense the colour the more intense the � avour that tends to be reported and vice versa. For example, chocolate pudding that is a richer shade of brown has a stronger � avour, as does chicken bouillon that has twice the level of normal colouring added. Egg yolks taste better when a rich orange colour, butter when pale yellow, margarine when it looks more like butter and brighter red salsas are perceived as spicier. When bright white colouring is added to skim milk it is perceived to be smoother, better tasting, and higher in fat than the uncoloured milk.

This type of colour intensity effect has been found with everything from noodles to vegetables, and from cheese through to yoghurt, as well as cake, jams, jellies, chocolates and sherbets (Chan & Kane-Martinelli 1997; Shermer & Levitan 2014).

TextureWe often describe ice cream, yoghurt or custard as having a creamy taste. That ‘creaminess’ is more about how the food feels in the mouth than about actual cream content. Texture is the property of food or beverage that is felt in the mouth and contributes to � avour along with taste, vision and other sensations. Crispy, crunchy, crackly, gritty, grainy, chewy, sticky, soft, hard, smooth, rough, runny, lumpy, slimy, oily, greasy, dry, bubbly, � zzy, moist, rich, juicy and succulent are some of the other words that refer to texture when eating or drinking.

Texture stimulates tactile sensations and is therefore perceived in response to touch, primarily in the mouth. It can affect � avour in at least two important ways. First, the texture of the food we eat helps to determine how much of its surface area can come in contact with our taste receptors. For example, consider the difference in � avour intensity between carrot chunks, grated carrot and carrot juice. When you put a big chunk of carrot in your mouth, you do not taste much until you crunch down on it and break it into smaller pieces. Taste a forkful of grated carrot, and its � avour is much more noticeable. Sip on a glass of carrot juice, and you are likely to get a blast of carrot � avour immediately (Zimmerman, 2004).

FIGURE 8.11 There tends to be an expectation that more intensely coloured foods are likely to be more intensely � avoured. Overall � avour intensity is in� uenced by the amount of colouring that is added; for example, the more intense the colour of yoghurt, the more intense the � avour that is reported.

Practical activity on colour and � avour perception

UNCORRECTED but differing degrees of sweetness, most tasters did

UNCORRECTED but differing degrees of sweetness, most tasters did not report a different in taste. Then, when asked

UNCORRECTED not report a different in taste. Then, when asked to taste orange juice in which a � avourless green

UNCORRECTED to taste orange juice in which a � avourless green colour tinge was added, a signi� cant number of

UNCORRECTED colour tinge was added, a signi� cant number of participants reported the presence of sourness. In

UNCORRECTED participants reported the presence of sourness. In a similar study, participants who drank strawberry-

UNCORRECTED a similar study, participants who drank strawberry- and cherry-� avoured juices reported that drinks with

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and cherry-� avoured juices reported that drinks with more red colour tasted stronger and had ‘more’ and

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more red colour tasted stronger and had ‘more’ and ‘truer’ strawberry and cherry � avours. The effect

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‘truer’ strawberry and cherry � avours. The effect was stronger among older than younger tasters

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was stronger among older than younger tasterset al.,

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et al., 2014).

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2014). Studies that have manipulated the colour intensity

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Studies that have manipulated the colour intensity of food have also reported distorted perceptions of

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of food have also reported distorted perceptions of � avour. As with drink studies, the colour is intensi� ed

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� avour. As with drink studies, the colour is intensi� ed using a food dye but there is no actual change in

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using a food dye but there is no actual change in � avour. The results of food studies also show that

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� avour. The results of food studies also show that overall � avour intensity is in� uenced by the amount

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overall � avour intensity is in� uenced by the amount of colouring that is added — the more intense the UNCORRECTED

of colouring that is added — the more intense the colour the more intense the � avour that tends to UNCORRECTED

colour the more intense the � avour that tends to be reported and vice versa. For example, chocolate UNCORRECTED

be reported and vice versa. For example, chocolate

Martinelli 1997; Shermer & Levitan 2014).

UNCORRECTED Martinelli 1997; Shermer & Levitan 2014).PAGE

This type of colour intensity effect has been found

PAGE This type of colour intensity effect has been found

with everything from noodles to vegetables, and

PAGE with everything from noodles to vegetables, and from cheese through to yoghurt, as well as cake, PAGE from cheese through to yoghurt, as well as cake, jams, jellies, chocolates and sherbets (Chan & Kane-PAGE

jams, jellies, chocolates and sherbets (Chan & Kane-PAGE

PAGE more intense the colour of yoghurt, the more intense

PAGE more intense the colour of yoghurt, the more intense the � avour that is reported.

PAGE the � avour that is reported.

PAGE PROOFS

PROOFS

PROOFS

PROOFS

PROOFS

PROOFS

PROOFSThere tends to be

PROOFSThere tends to be

an expectation that more intensely

PROOFSan expectation that more intensely coloured foods are likely to be

PROOFScoloured foods are likely to be more intensely � avoured. Overall

PROOFSmore intensely � avoured. Overall � avour intensity is in� uenced by

PROOFS

� avour intensity is in� uenced by the amount of colouring that is added; for example, the PROOFS

the amount of colouring that is added; for example, the more intense the colour of yoghurt, the more intense PROOFS

more intense the colour of yoghurt, the more intense the � avour that is reported.PROOFS

the � avour that is reported.PROOFS

PROOFS

PROOFSPractical activity on

PROOFSPractical activity on

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The length of time food spends in the mouth also affects how strong its � avour seems. Thicker liquids and rich foods coat the mouth. Consequently, their tastants spend more time exposed to taste receptors than thinner liquids and leaner foods, so they often seem more � avourful. Dense foods, likewise, come into contact with more receptors than do aerated, lighter foods. Chewy foods take longer to break down enough to swallow than do softer foods, so we get more � avour from them. Studies show that people, for example, tend to judge the � avour of yoghurt or custard as creamier and more � avoursome and � lling when it is thick, provides more mouth coating and is slow to melt (McCrickerd, et al, 2012; Zimmerman, 2004).

In many cases, what we like and dislike about the texture of our food is a direct result of what we expect from a particular food. ‘Chewy’, for example, is a textural feature that we like when we’re talking about a muesli bar or licorice, but not when we’re talking about steak or biscuits. Similarly, crispy or crunchy is what we expect and want from Twisties or pretzels but not from custard or scrambled eggs.

Texture contributes to the overall acceptability of a food or beverage, as well as to its appearance and � avour. Our expectation of how food should feel in

the mouth is manipulated by food producers and marketers to in� uence our choices. For example, potato chips and crackers are advertised as crispy, butter and margarine as smooth, oranges as juicy, meat and chicken as succulent, ice cream as creamy, gravy as rich and carbonated drinks as � zzy or bubbly. This occurs whether or not it is true. Chefs and food manufacturers use starches, thickeners and emulsi� ers to help create the ‘creamy’ taste they promote. However, a sauce’s � avour can be judged as being ‘creamy’ without actually containing cream.

FIGURE 8.12 Texture is the property of food that contributes to � avour along with the sensory input.

BOX 8.2

Does the colour of the mug in� uence the taste of the coffee?About a billion cups of coffee are consumed in cafés, restaurants and other outlets throughout Australia each year. Australian psychologist George Van Doorn and his colleagues (2015) conducted research to � nd out if consumers’ perception of a café latte would be in� uenced by the colour (transparent, white or blue) of the mug from which it was drunk.

In one experiment, nine male and nine female volunteer participants aged between 18 and 62 years with a mean age of 31.5 years were randomly allocated to either of three groups, with three males and three females in each group. Participants were told that the purpose of the study was to assess certain characteristics of coffee.

All drank ~200 mL of café latte (~135 mL of full-cream milk and ~65 mL of coffee). Group 1 were given their coffee in a white, porcelain mug, group 2 in a transparent, glass mug and group 3 in a blue, porcelain mug (like the mugs shown in � gure 8.13).

Once the participants had drunk their coffee, they rated the coffee on � ve characteristics using a 100-point scale.

For example, for � avour intensity, a score of 0 = not intense at all and a score of 100 = very intense. These results are shown in table 8.1.

The researchers concluded that the colour of the mug in� uenced participants’ ratings of the coffee taste/� avour. On the basis of this � nding, they recommended that ‘café owners, baristas, as well as crockery manufacturers should carefully consider the colour of the mug and the potential effects that its colour may exert over the multisensory coffee drinking experience’.

TABLE 8.1 The mean subjective ratings of the perceived intensity, aroma, bitterness, quality and acceptability of the coffee as a function of mug type

MugFlavour

intensity Aroma Bitterness QualityAcceptability

(likeability)

White 35.46 38.18 36.00 50.57 40.38

Blue 31.16 29.71 27.34 49.48 55.58

Glass 29.97 24.08 24.86 33.85 43.80

Source: Van Doorn, G. H., Wuillemin, D., & Spence, C. (2014). Does the colour of the mug in� uence the taste of the coffee? Flavour, 3(10).

FIGURE 8.13 <Caption TBA>

UNCORRECTED Does the colour of the mug in� uence the

UNCORRECTED Does the colour of the mug in� uence the

About a billion cups of coffee are consumed in cafés,

UNCORRECTED About a billion cups of coffee are consumed in cafés, restaurants and other outlets throughout Australia

UNCORRECTED restaurants and other outlets throughout Australia each year. Australian psychologist George Van Doorn

UNCORRECTED each year. Australian psychologist George Van Doorn and his colleagues (2015) conducted research to � nd

UNCORRECTED and his colleagues (2015) conducted research to � nd out if consumers’ perception of a café latte would be

UNCORRECTED out if consumers’ perception of a café latte would be in� uenced by the colour (transparent, white or blue) of the

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in� uenced by the colour (transparent, white or blue) of the

In one experiment, nine male and nine female volunteer

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In one experiment, nine male and nine female volunteer participants aged between 18 and 62 years with a mean

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participants aged between 18 and 62 years with a mean age of 31.5 years were randomly allocated to either of

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age of 31.5 years were randomly allocated to either of three groups, with three males and three females in each

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three groups, with three males and three females in each group. Participants were told that the purpose of the

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group. Participants were told that the purpose of the study was to assess certain characteristics of coffee.

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study was to assess certain characteristics of coffee. All drank ~200 mL of café latte (~135 mL of full-cream

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All drank ~200 mL of café latte (~135 mL of full-cream milk and ~65 mL of coffee). Group 1 were given their

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milk and ~65 mL of coffee). Group 1 were given their coffee in a white, porcelain mug, group 2 in a transparent,

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coffee in a white, porcelain mug, group 2 in a transparent,

UNCORRECTED

glass mug and group 3 in a blue, porcelain mug (like the

UNCORRECTED

glass mug and group 3 in a blue, porcelain mug (like the mugs shown in � gure 8.13).UNCORRECTED

mugs shown in � gure 8.13).Once the participants had drunk their coffee, they rated UNCORRECTED

Once the participants had drunk their coffee, they rated the coffee on � ve characteristics using a 100-point scale. UNCORRECTED

the coffee on � ve characteristics using a 100-point scale.

intense at all and a score of 100 = very intense. These

UNCORRECTED intense at all and a score of 100 = very intense. These results are shown in table 8.1.

UNCORRECTED results are shown in table 8.1.

PAGE

PAGE

PAGE

PAGE FIGURE 8.12

PAGE FIGURE 8.12 Texture is the property of food that

PAGE Texture is the property of food that

contributes to � avour along with the sensory input.

PAGE contributes to � avour along with the sensory input.

PAGE

PAGE

PAGE

PAGE

PAGE

For example, for � avour intensity, a score of 0 = not PAGE

For example, for � avour intensity, a score of 0 = not

PROOFS

PROOFS

PROOFS



345


Review questions

1 Explain the meaning of � avour.2 How is � avour distinguished from taste?

3 Complete the following table to summarise how � avour is judged and can be in� uenced.

Factor Description

In� uence on � avour judgement

Example of manipulation by a food producer or marketer

to in� uence purchase

Example of manipulation by a chef/restaurant to

in� uence � avour judgement

Perceptual set

Colour intensity

Texture

Word copy


Analysis of research on colour and coffee tasteConsider the research about the colour of the mug and its in� uence on the taste of the coffee described in box 8.2 on page 000. Analyse the research by answering the following questions.1 Formulate a relevant research hypothesis.2 Name the experimental research design.3 Identify the operationalised IVs and DVs.4 Identify the experimental and control groups.5 Describe the results obtained.6 Suggest two potential extraneous or confounding

variables relating to the coffee and/or mugs that needed to be strictly controlled.

SYNAESTHESIAWhen Matthew Blakeslee shapes hamburger patties with his hands, he experiences a vivid bitter taste in his mouth. Esmeralda Jones sees blue when she listens to the note C sharp played on the piano; other notes produce different colours — so much so that the piano keys are actually colour coded, making it easier for her to remember and play musical scales. And when Jeff Coleman looks at printed black numbers, he sees them in colour, each a different colour. Blakeslee, Jones and Coleman experience the ordinary world in extraordinary ways. For them, the senses get intertwined instead of remaining separate. They are among a few otherwise normal people who have synaesthesia (Ramachandran & Hubbard, 2003).

Synaesthesia (pronounced ‘sin-ess-THEE-zhah’) is a perceptual experience in which stimulation of one sense produces additional unusual experiences in another sense. The experience associated with the additional sense ‘adds’ to the overall perceptual experience without replacing the initial sense.

Researchers have found that synaesthesia is a real experience (rather than imagined) and can

be distinguished by a number of characteristics. Synaesthesia is involuntary and occurs automatically in response to the relevant sensory stimulation. It is extremely dif� cult to suppress. The experience is also vivid, highly memorable and consistent across time. For example, the synaesthete always associates the same colour with the same number, letter of the alphabet or sound. Blue will always be experienced with the number three, or T’s are always red to the individual synaesthete. However, these speci� c cross-sensory experiences vary among individual synaesthetes. For example, one synaesthete may always experience blue with the number three, whereas another may always experience yellow with the number three. Finally, synaesthesia also tends to be one-way rather than bidirectional. If a sound produces a taste, the taste will not necessarily produce the sound (Hubbard & Ramachandran, 2003; Ward & Mattingly, 2006).

(a)

(b)

FIGURE 8.14 Synaesthesia is a perceptual experience in which stimulation of one sense produces additional unusual experiences in another sense: (a) how letters usually appear; (b) how letters appear to a person with synaesthesia.

Weblinks • Video on synaesthesia

3 m 57 s• Documentary on

synaesthesia 28 m 57 s

Although synaesthesia was � rst scienti� cally investigated around 1880, it was brushed aside as fakery or a mere curiosity for many years. More recently, psychologists have developed renewed interest in synaesthesia and are now conducting research investigations on the phenomenon.

UNCORRECTED

UNCORRECTED

UNCORRECTED Suggest two potential extraneous or confounding

UNCORRECTED Suggest two potential extraneous or confounding variables relating to the coffee and/or mugs that

UNCORRECTED variables relating to the coffee and/or mugs that

When Matthew Blakeslee shapes hamburger patties

UNCORRECTED

When Matthew Blakeslee shapes hamburger patties with his hands, he experiences a vivid bitter taste

UNCORRECTED

with his hands, he experiences a vivid bitter taste in his mouth. Esmeralda Jones sees blue when she

UNCORRECTED

in his mouth. Esmeralda Jones sees blue when she listens to the note C sharp played on the piano; other

UNCORRECTED

listens to the note C sharp played on the piano; other notes produce different colours — so much so that

UNCORRECTED

notes produce different colours — so much so that the piano keys are actually colour coded, making it

UNCORRECTED

the piano keys are actually colour coded, making it easier for her to remember and play musical scales.

UNCORRECTED

easier for her to remember and play musical scales. And when Jeff Coleman looks at printed black

UNCORRECTED

And when Jeff Coleman looks at printed black numbers, he sees them in colour, each a different

UNCORRECTED

numbers, he sees them in colour, each a different colour. Blakeslee, Jones and Coleman experience the

UNCORRECTED

colour. Blakeslee, Jones and Coleman experience the

UNCORRECTED

ordinary world in extraordinary ways. For them, the UNCORRECTED

ordinary world in extraordinary ways. For them, the senses get intertwined instead of remaining separate. UNCORRECTED

senses get intertwined instead of remaining separate. They are among a few otherwise normal people who UNCORRECTED

They are among a few otherwise normal people who

tends to be one-way rather than bidirectional. If a sound

UNCORRECTED tends to be one-way rather than bidirectional. If a sound produces a taste, the taste will not necessarily produce

UNCORRECTED produces a taste, the taste will not necessarily produce PAGE colour with the same number, letter of the alphabet or

PAGE colour with the same number, letter of the alphabet or sound. Blue will always be experienced with the number

PAGE sound. Blue will always be experienced with the number three, or T’s are always red to the individual synaesthete.

PAGE three, or T’s are always red to the individual synaesthete. However, these speci� c cross-sensory experiences

PAGE However, these speci� c cross-sensory experiences vary among individual synaesthetes. For example,

PAGE vary among individual synaesthetes. For example, one synaesthete may always experience blue with the

PAGE one synaesthete may always experience blue with the number three, whereas another may always experience PAGE number three, whereas another may always experience PAGE

yellow with the number three. Finally, synaesthesia also PAGE

yellow with the number three. Finally, synaesthesia also tends to be one-way rather than bidirectional. If a sound PAGE

tends to be one-way rather than bidirectional. If a sound

PROOFS

PROOFS

PROOFS

PROOFS

PROOFS

PROOFS

PROOFSbe distinguished by a number of characteristics.

PROOFSbe distinguished by a number of characteristics. Synaesthesia is involuntary and occurs automatically

PROOFSSynaesthesia is involuntary and occurs automatically in response to the relevant sensory stimulation. It is

PROOFSin response to the relevant sensory stimulation. It is extremely dif� cult to suppress. The experience is also

PROOFSextremely dif� cult to suppress. The experience is also vivid, highly memorable and consistent across time. For

PROOFS

vivid, highly memorable and consistent across time. For example, the synaesthete always associates the same PROOFS

example, the synaesthete always associates the same colour with the same number, letter of the alphabet or PROOFS

colour with the same number, letter of the alphabet or sound. Blue will always be experienced with the number PROOFS

sound. Blue will always be experienced with the number



Much research still needs to be done, but it has been found that there may be unusual brain processes associated with synaesthesia and that there may be a genetic basis to its experience, as it tends to run in families. However, there is no strong evidence for sex differences in its experience (Hubbard & Ramachandran, 2003).

Synaesthesia is relatively rare and there are substantial individual differences among people in how they experience it. Estimates of its prevalence vary from as much as 1 in 20 people to as few as 1 in 25 000 people. An estimate of about 1 in 2000 people seems to be widely accepted within psychology. Some forms of synaesthesia are more common than others. For example, the experience of seeing colours produced by sounds, or seeing letters in speci� c colours, is more common among synaesthetes than a smell produced by touching a particular shape or a taste produced by hearing words.

One of the most common and widely studied forms of synaesthesia is called grapheme-colour synaesthesia, in which viewing letters or numbers produces the experience of colours. Synaesthetes who have this experience report that looking at a speci� c letter of the alphabet will evoke a speci� c colour or a ‘coloured overlay’. Other synaesthetes report that they do not actually see the colours but instead just ‘know’ that a particular letter is a particular colour. Still others report experiencing speci� c colours but say that the colour is experienced somewhere within their ‘mind’s eye’ (Hubbard & Ramachandran, 2003).

FIGURE 8.15 In grapheme-colour synaesthesia, viewing letters or numbers produces the experience of colours.

Explanations of synaesthesiaResearchers still know relatively little about synaesthesia and why it is experienced. Many explanations have been proposed for its occurrence. Some researchers have suggested that synaesthetes are unusually sensitive to external stimuli. Others have proposed that synaesthesia may result from a breakdown in sensory and perceptual processes. It has also been suggested that synaesthesia can be linked to the excess of neural connections formed during early development that are normally pruned and re� ned as the brain matures over time. Therefore, synaesthetes may be people who retain rather than lose these neural connections.

Many psychologists agree that it is likely that the brains of synaesthetes possess unique structural and/or functional properties. Consequently, explanations often refer to the possibility of differences in the architecture of the synaesthete’s brain. For example, the brains of synaesthetes may have abnormal nerve pathways or be ‘wired’ differently, so that neighbouring sensory areas in the brain cross-activate one another, thereby triggering additional sensations — the experience of seeing colour when looking at shapes might be due to cross-activation of the colour and shape recognition.

Neuroimaging technology has been very useful for studying brain areas that are active during synaesthesia, but the images are not yet detailed enough to allow researchers to see whether the individual connections in the brain are cross-wired. When enough known synaesthetes die and donate their brains for research, post-mortem examinations may provide valuable information on what is different about their brains and what may therefore account for their extraordinary perceptual experiences.

It is likely that something is ‘going on’ in the sensory areas of the brain, but precisely what still remains unclear. It is, however, clear that synaesthesia is not associated with any serious brain abnormality or problems with cognitive functioning. Nor is it some kind of ‘sixth sense’.

Researchers usually study synaesthesia not only because it is an unusual perceptual experience, but also because it may shed new light on how the brain is organised and how we sense and perceive the world. It may offer new insights on brain areas and cognitive processes involved in perception. For example, it raises questions on how the different senses interact in the brain; how we ‘bind’ all perceptions together into one complete whole; how different types of information are represented in the brain; and on the overlap between cognitive processes such as perception, imagery, language, memory and conscious awareness.

UNCORRECTED that the colour is experienced somewhere within their

UNCORRECTED that the colour is experienced somewhere within their

UNCORRECTED synaesthesia, but the images are not yet detailed

UNCORRECTED synaesthesia, but the images are not yet detailed enough to allow researchers to see whether the

UNCORRECTED enough to allow researchers to see whether the PAGE differently, so that neighbouring sensory areas

PAGE differently, so that neighbouring sensory areas in the brain cross-activate one another, thereby

PAGE in the brain cross-activate one another, thereby

PAGE triggering additional sensations — the experience

PAGE triggering additional sensations — the experience of seeing colour when looking at shapes might be

PAGE of seeing colour when looking at shapes might be due to cross-activation of the colour and shape

PAGE due to cross-activation of the colour and shape recognition.

PAGE recognition.

Neuroimaging technology has been very useful PAGE Neuroimaging technology has been very useful

for studying brain areas that are active during PAGE

for studying brain areas that are active during synaesthesia, but the images are not yet detailed PAGE

synaesthesia, but the images are not yet detailed

PROOFSduring early development that are normally pruned

PROOFSduring early development that are normally pruned and re� ned as the brain matures over time. Therefore,

PROOFSand re� ned as the brain matures over time. Therefore, synaesthetes may be people who retain rather than

PROOFSsynaesthetes may be people who retain rather than

Many psychologists agree that it is likely that the

PROOFSMany psychologists agree that it is likely that the

brains of synaesthetes possess unique structural

PROOFSbrains of synaesthetes possess unique structural and/or functional properties. Consequently,

PROOFSand/or functional properties. Consequently, explanations often refer to the possibility of

PROOFSexplanations often refer to the possibility of differences in the architecture of the synaesthete’s

PROOFSdifferences in the architecture of the synaesthete’s brain. For example, the brains of synaesthetes

PROOFS

brain. For example, the brains of synaesthetes may have abnormal nerve pathways or be ‘wired’ PROOFS

may have abnormal nerve pathways or be ‘wired’ differently, so that neighbouring sensory areas PROOFS

differently, so that neighbouring sensory areas in the brain cross-activate one another, thereby PROOFS

in the brain cross-activate one another, thereby



347

A special few can ‘taste’ a word before they can say it By J.R. Minkel

TASTE OF THE UNKNOWN: Words caught on the tip of the tongue elicit tastes in people with an unu-sual mixing of the senses called synaesthesia.

Having a word stuck on the tip of the tongue is enough to activate an unusual con-dition in which some people perceive words as having dif-ferent tastes, according to a new study. When people with the inherited condition, called synaesthesia, looked at pic-tures of objects that come up infrequently in conversation, they perceived a taste before they could think of the word.

Some researchers believe synaesthesia is an extreme version of what happens in everyone’s mind. If so, the result suggests that all abstract thoughts are associated with specific perceptions, says neuropsychologist Julia Simner of the University of Edinburgh, co-author of the report. ‘The extent to which abstract thought is truly abstract — that’s really what the question is.’

Simner and her colleague Jamie Ward of University College London tested six synaesthetes by showing them pictures of 96 uncommon objects such as a gazebo, sextant, catamaran, artichoke or castanets. Out of 550 trials in total, Simner and Ward induced 89 tip-of-the-tongue states. In 17 of these ‘um, um’ moments, the synaesthete reported perceiving a taste while still trying to conjure the word. In short, the word’s meaning alone elicited the taste.

To confirm that these reports were truthful the researchers called the participants out of

the blue a year later and retested them. The synaesthetes consistently associated the same tastes with the same words, the researchers report in the November 22 Nature.

‘This looks pretty clever,’ says neuro-scientist David Eagleman of Baylor Medical College, who was not involved in the study. Synaesthesia research has blossomed in the last five years, as researchers have gained confidence in the subjective reports of pre-sumed synaesthetes, especially those who perceive letters or numbers as being colored, he says. ‘Essentially all the synaesthesia lit-erature is about color just because it’s easier to study. This is stepping beyond that.’ Some experts have estimated that there are more than 150 kinds of synaesthesia, based on the possible combinations of subjective sen-sations, he says.

Prior experiments found that the word-taste associations are locked in during ado-lescence and have some definite patterns,

Simner explains. These synaesthetes tend to taste childhood things such as chocolate and lollipops, she says. ‘Some of these tastes are really strong and some of them are really unpleasant — some of them taste of earwax and bodily fluids,’ she notes. ‘It starts with words like ‘mince’ and ‘cabbage,’ and the taste experience spread to similarly sounding words.’ ‘Prince’ might also taste of mince, for example. Some of the associations have seem-ingly obvious roots — ‘news-paper’ might taste like fish and chips, which traditionally comes wrapped in news-print, she adds.

The brain wiring necessary for synaes-thesia seems to be present in everyone. Drop-ping acid or drifting to sleep can both cause synaesthetic perceptions, and people who are blindfolded for extended periods may start seeing colors for different sounds, the experts note. ‘It’s possible that we all have that con-nection but the synaesthetes have them to an extreme degree,’ says Simner.

Some scientists have theorized that we are born synaesthetic but lose or block most of the pathways that cause the unusual percep-tions, Simner observes. Eagleman disagrees, saying that the condition may be the result of an imbalance in brain signals. He hopes to identify the gene for familial synaesthesia in order to learn more, he says.

Source: Minkel, J.R. (2006). A special few can ‘taste’ a word before they can say it. Scienti� c American. Retrieved from http://www.scienti� camerican.com/

article/a-special-few-can-taste-a/


Review questions

1 Explain what synaesthesia is.2 List the key distinguishing characteristics of

synaesthesia.3 Give a possible explanation of synaesthesia that

is based on (a) brain dysfunction(b) healthy brain function.


Media responseRead the above article on synaesthesia and explain how accurately it describes and explains synaesthesia with reference to information in this text.

UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED Out of 550 trials in total, Simner and Ward

UNCORRECTED Out of 550 trials in total, Simner and Ward induced 89 tip-of-the-tongue states. In 17

UNCORRECTED

induced 89 tip-of-the-tongue states. In 17 of these ‘um, um’ moments, the synaesthete

UNCORRECTED

of these ‘um, um’ moments, the synaesthete reported perceiving a taste while still trying

UNCORRECTED

reported perceiving a taste while still trying to conjure the word. In short, the word’s

UNCORRECTED

to conjure the word. In short, the word’s meaning alone elicited the taste.

UNCORRECTED

meaning alone elicited the taste.To confirm that these reports were truthful

UNCORRECTED

To confirm that these reports were truthful To confirm that these reports were truthful

UNCORRECTED

To confirm that these reports were truthful the researchers called the participants out of

UNCORRECTED

the researchers called the participants out of

College, who was not involved in the study.

UNCORRECTED College, who was not involved in the study. College, who was not involved in the study.

UNCORRECTED College, who was not involved in the study. Synaesthesia research has blossomed in the

UNCORRECTED Synaesthesia research has blossomed in the Synaesthesia research has blossomed in the

UNCORRECTED Synaesthesia research has blossomed in the last five years, as researchers have gained

UNCORRECTED last five years, as researchers have gained last five years, as researchers have gained

UNCORRECTED last five years, as researchers have gained confidence in the subjective reports of pre-

UNCORRECTED confidence in the subjective reports of pre-confidence in the subjective reports of pre-

UNCORRECTED confidence in the subjective reports of pre-sumed synaesthetes, especially those who

UNCORRECTED sumed synaesthetes, especially those who sumed synaesthetes, especially those who

UNCORRECTED sumed synaesthetes, especially those who perceive letters or numbers as being colored,

UNCORRECTED perceive letters or numbers as being colored, he says. ‘Essentially all the synaesthesia lit-

UNCORRECTED he says. ‘Essentially all the synaesthesia lit-erature is about color just because it’s easier

UNCORRECTED erature is about color just because it’s easier to study. This is stepping beyond that.’ Some

UNCORRECTED

to study. This is stepping beyond that.’ Some experts have estimated that there are more

UNCORRECTED

experts have estimated that there are more than 150 kinds of synaesthesia, based on

UNCORRECTED

than 150 kinds of synaesthesia, based on

UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED

LEARNING ACTIVITY 8.4UNCORRECTED


Review questionsUNCORRECTED

Review questions

PAGE the blue a year later and retested them. The

PAGE the blue a year later and retested them. The synaesthetes consistently associated the same

PAGE synaesthetes consistently associated the same tastes with the same words, the researchers

PAGE tastes with the same words, the researchers

Nature

PAGE Nature.

PAGE .

‘This looks pretty clever,’ says neuro-

PAGE ‘This looks pretty clever,’ says neuro-

scientist David Eagleman of Baylor Medical PAGE scientist David Eagleman of Baylor Medical College, who was not involved in the study. PAGE

College, who was not involved in the study. Synaesthesia research has blossomed in the PAGE

Synaesthesia research has blossomed in the PAGE PROOFS

PROOFS

PROOFSare really strong and some of

PROOFSare really strong and some of them are really unpleasant —

PROOFSthem are really unpleasant — some of them taste of earwax

PROOFSsome of them taste of earwax some of them taste of earwax

PROOFSsome of them taste of earwax and bodily fluids,’ she notes.

PROOFSand bodily fluids,’ she notes. ‘It starts with words like

PROOFS‘It starts with words like ‘mince’ and ‘cabbage,’ and

PROOFS‘mince’ and ‘cabbage,’ and the taste experience spread

PROOFSthe taste experience spread to similarly sounding words.’

PROOFSto similarly sounding words.’ ‘Prince’ might also taste of

PROOFS‘Prince’ might also taste of mince, for example. Some of

PROOFSmince, for example. Some of the associations have seem-

PROOFSthe associations have seem-ingly obvious roots — ‘news-

PROOFS

ingly obvious roots — ‘news-

PROOFS

PROOFS

UNIT 2 How do external factors in�uence behaviour and mental processes?348


CHAPTER SUMMARY

Visual illusions

Judgement of �avours

Synaesthesia

Müller-Lyer illusion

Perceptual set

Ames room illusion

Colour intensity

Texture

Biological perspective

Psychological perspective

Social perspective

Explanations of synaesthesia

DISTORTIONS OFPERCEPTION

UNCORRECTED PAGE

Explanations of synaesthesia

PAGE Explanations of synaesthesia

PROOFS

CHAPTER 8 TEST

349



SECTION A – Multiple-choice questionsChoose the response that is correct or that best answers the question. A correct answer scores 1, an incorrect answer scores 0. Marks will not be deducted for incorrect answers. No marks will be given if more than one answer is completed for any question.

Question 1

A visual illusion is best described as

A. consistent misinterpretation of real sensory stimuli.

B. a trick involving the visual perception system.C. a false belief despite obvious proof that what is being

looked at is incorrect.D. a perception that occurs without external stimulation

of the eye.

Question 2

The Müller-Lyer illusion demonstrates that if the retinal images of two lines are identical, then people who grew up in ‘carpentered worlds’

A. cannot be fooled.B. can make perceptual errors unless a ruler is

available.C. will usually interpret the two lines as being of the

same length.D. can �nd themselves making errors of judgement by

ignoring ‘carpentered world’ cues.

Question 3

An explanation of an illusion in terms of ‘mis�ring neural impulses’ is likely to be based on the _______ perspective.

A. biologicalB. psychologicalC. socialD. biopsychosocial

Question 4

The Ames room illusion demonstrates that

A. viewing objects over a stretch of visible terrain can distort perception.

B. perception is more accurate when we use monocular cues as well as binocular cues.

C. we always maintain size constancy over shape constancy.

D. if two things appear to be the same distance away but have retinal images indicating that they are different sizes, then perceived size is determined by the size of the retinal images.

Question 5

In relation to taste perception, which of the following is a characteristic of texture?

A. ColourB. LabellingC. PackagingD. Mouthfeel

Question 6

The physical stimulus for texture perception is

A. colour.B. mouthfeel.C. touch.D. colour intensity.

Question 7

Which of the following points is correct about synaesthesia?

A. An imagined experienceB. Involves perceptual distortionsC. Causes brain injuryD. Caused by brain injury

Question 8

The �avour of food is determined by

A. taste.B. tastants.C. the brain.D. the food properties.

Question 9

The visual cue that tends to be predominant in the judgement of �avour judgement is

A. colour.B. labelling.C. packaging.D. light.

Question 10

Research �ndings indicate that more intensely coloured foods or drinks are likely to be perceived as

A. sweeter.B. unhealthy.C. lacking in �avour. D. more intensely �avoured.

UNCORRECTED usually interpret the two lines as being of the

UNCORRECTED usually interpret the two lines as being of the

�nd themselves making errors of judgement by

UNCORRECTED �nd themselves making errors of judgement by

An explanation of an illusion in terms of ‘mis�ring

UNCORRECTED

An explanation of an illusion in terms of ‘mis�ring neural impulses’ is likely to be based on the _______

UNCORRECTED

neural impulses’ is likely to be based on the _______

biopsychosocial

UNCORRECTED

biopsychosocial

uestion 4

UNCORRECTED

uestion 4

The Ames room illusion demonstrates thatUNCORRECTED

The Ames room illusion demonstrates that

wing objects over a stretch of visible terrain can UNCORRECTED

wing objects over a stretch of visible terrain can

Which of the following points is correct about synaesthesia?

UNCORRECTED Which of the following points is correct about synaesthesia?PAGE The physical stimulus for texture perception is

PAGE The physical stimulus for texture perception is

colour

PAGE colour.

PAGE .

mouthfeel.

PAGE mouthfeel.touch.

PAGE touch.

D. PAGE D. PAGE

colour PAGE colour intensity.PAGE

intensity.

Question 7PAGE

Question 7

PROOFSIn relation to taste perception, which of the following is a

PROOFSIn relation to taste perception, which of the following is a

UNIT 2 How do external factors in�uence behaviour and mental processes?350


SECTION B — Short-answer questions

Question 1 (2 marks)

Explain the meaning of the phrase ‘distortion of perception’.


(a) Give an explanation of a visual illusion from a biological, psychological or social perspective. (3 marks)

(b) Brie�y discuss whether illusions or misperceptions of taste or �avours may be better understood if approached from a biopsychosocial perspective rather than a single perspective. (2 marks)


(a) De�ne food texture. (2 marks)

(b) Explain the role of tastants in texture perception. (1 mark)


Distinguish between taste perception and �avour perception. UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED

UNCORRECTED

the role of tastants in texture perception.

UNCORRECTED

the role of tastants in texture perception.

Question 4

UNCORRECTED

Question 4 (

UNCORRECTED

(2 marks)

UNCORRECTED

2 marks)

UNCORRECTED

Distinguish between taste perception and �avour perception. UNCORRECTED

Distinguish between taste perception and �avour perception.

PAGE

PAGE

PAGE

PAGE

PAGE discuss whether illusions or misperceptions of taste or �avours may be better understood if approached from a

PAGE discuss whether illusions or misperceptions of taste or �avours may be better understood if approached from a PROOFS

PROOFS

PROOFS

PROOFS

PROOFS

PROOFSmarks)

PROOFSmarks)

discuss whether illusions or misperceptions of taste or �avours may be better understood if approached from a PROOFS

discuss whether illusions or misperceptions of taste or �avours may be better understood if approached from a



351


Explain how perceptual set can in�uence �avour perception with reference to an example.


(a) List three distinguishing characteristics of synaesthesia. (3 marks)

(b) Explain whether synaesthesia can be considered to be a perceptual distortion. (2 marks)

The answers to the multiple-choice questions are in the answer section at the back of this book and in eBookPLUS.

The answers to the short-answer questions are in eBookPLUS.

UNCORRECTED PAGE P

ROOFS

PROOFS

PROOFS

PROOFS

PROOFS

marks)

PROOFS

marks)

Documents

Distortions of perception · perceptual distortion. A perceptual distortion involves an inconsistency, or ‘mismatch’, between a perceptual experience and physical reality. Visual