Chapter 4Chapter 4

Sensation and Sensation and PerceptionPerception

Section 1Section 1

Sensation and Perception:Sensation and Perception:

The BasicsThe Basics

Sensation Sensation

The stimulation of sensory receptors and the The stimulation of sensory receptors and the transmission of sensory information to the transmission of sensory information to the central nervous system central nervous system Brain and spinal cordBrain and spinal cord

Sensory receptors are located in the eyes, Sensory receptors are located in the eyes, ears and elsewhere in the body.ears and elsewhere in the body.

The stimulation of the senses is automaticThe stimulation of the senses is automatic

PerceptionPerception

Process through which we interpret Process through which we interpret sensory simulation.sensory simulation.

Reflects learning, expectations and Reflects learning, expectations and attitudes.attitudes.

Stimulation of the senses and the Stimulation of the senses and the ways in which people interpret that ways in which people interpret that stimulation is effected by conceptsstimulation is effected by concepts

1.1. Absolute thresholdAbsolute threshold

2.2. Difference thresholdDifference threshold

3.3. Signal detection theorySignal detection theory

4.4. Sensory adaptationSensory adaptation

Absolute ThresholdAbsolute Threshold

The weakest amount of a stimulus that The weakest amount of a stimulus that can be sense.can be sense.

Some people are more sensitive than Some people are more sensitive than otherother

Hearing testHearing test The first sound you can hearThe first sound you can hear

Difference ThresholdDifference Threshold

Low enough so we can see, hear, smell, Low enough so we can see, hear, smell, taste, and feeltaste, and feel

But not too low to overload us with But not too low to overload us with informationinformation

The minimum amount of difference that The minimum amount of difference that can be detected between 2 stimulican be detected between 2 stimuli

Paint chipsPaint chips Dark-darkDark-dark Dark-a little lighterDark-a little lighter

Signal Detection TheorySignal Detection Theory

A method of A method of distinguishing sensory distinguishing sensory stimuli that takes into stimuli that takes into account not only their account not only their strengths but also: strengths but also: SettingSetting Your physical stateYour physical state Your moodYour mood Your attitudesYour attitudes

Also considers Also considers psychological factors psychological factors such as:such as: MotivationsMotivations Expectations Expectations LearningLearning

We focus on what We focus on what we deem we deem importantimportant..

We focus on what we consider We focus on what we consider importantimportant

Sensory AdaptationSensory Adaptation

The process by which we become more The process by which we become more sensitive to real stimuli and less sensitive sensitive to real stimuli and less sensitive to unchanged stimulito unchanged stimuli Low light in a theaterLow light in a theater Noise of the cityNoise of the city

Section 2Section 2

VisionVision

““Seeing is believing”Seeing is believing”

Why do we put so much more trust in Why do we put so much more trust in evidence that we have seen than evidence evidence that we have seen than evidence we have heard? we have heard?

The eyeThe eye

Very similar to a cameraVery similar to a camera The amount of light entering the eye The amount of light entering the eye

determines the size of the pupil.determines the size of the pupil.

Very similar to a cameraVery similar to a camera The amount of light entering the eye The amount of light entering the eye

determines the size of the pupil.determines the size of the pupil.

Lens Retina Lens Retina

Adjusts to the Adjusts to the distance of objects distance of objects by changing its by changing its thicknessthickness When you squint, When you squint,

you’re adjusting the you’re adjusting the thickness. thickness.

The sensitive surface The sensitive surface in the eye that acts in the eye that acts like film in a cameralike film in a camera

PhotoreceptorsPhotoreceptors Neurons that are Neurons that are

sensitive to lightsensitive to light Carry visual input to Carry visual input to

the brainthe brain

2 type kinds of photoreceptors 2 type kinds of photoreceptors

Cones Cones Allow you to see in Allow you to see in

colorcolor

RodsRods Sensitive to Sensitive to

brightness of lightbrightness of light Allow you to see in Allow you to see in

black and whiteblack and white

Blind SpotBlind SpotThe Point where the

optic nerve leaves they eye. We would never be able to “see” without it.

Adaptation Adaptation Dark Dark light light

Walk into a dark room Walk into a dark room too dark to find a too dark to find a seatseat Starts to adjust to Starts to adjust to

lower lightlower light Will continue for 45 Will continue for 45

minutesminutes

Walking into a bright Walking into a bright roomroom A first blink/ hurtsA first blink/ hurts Within a minute you Within a minute you

can seecan see Adaptation to light Adaptation to light

happens a lot fasterhappens a lot faster

Visual acuityVisual acuity

Determined by the ability to see visual Determined by the ability to see visual details in normal lightdetails in normal light

NearsightedNearsighted Can not see details farther awayCan not see details farther away

FarsightedFarsighted Can not see details close upCan not see details close up

Color VisionColor Vision

Afterimages Afterimages Complementary color Complementary color

of the original color. of the original color. Staring at one will Staring at one will create an afterimage create an afterimage of another of another

Color VisionColor Vision

Color blindness Color blindness Partially or totally Partially or totally

unable to distinguish unable to distinguish color due to the color due to the absence of or absence of or malfunction in the malfunction in the conescones

Color VisionColor Vision

Optical IllusionsOptical Illusions

Mona LisaMona Lisa

Section 3Section 3

HearingHearing

HearingHearing

Sound is caused by the changes in air Sound is caused by the changes in air pressure that result from vibration.pressure that result from vibration.

Each vibration is called a cycle or a sound Each vibration is called a cycle or a sound wave.wave.

Every wave has it’s own pitch and Every wave has it’s own pitch and loudness.loudness.

PitchPitch

Pitch of a soundPitch of a sound How low and high the sound is depends How low and high the sound is depends

on its frequency or the # of cycle per on its frequency or the # of cycle per secondsecond

More cycles the higher the soundMore cycles the higher the sound Women- short Women- short

Higher voicesHigher voices Men- longMen- long

Lower voicesLower voices

LoudnessLoudness

is determined by the amplitude of sound wavesis determined by the amplitude of sound waves Is measured by decibelsIs measured by decibels

DeafnessDeafness

ConductiveConductive Occurs because of damage to the Occurs because of damage to the

middle ear (hearing aids)middle ear (hearing aids)

SensorineuralSensorineural Damage to the inner ear Damage to the inner ear

Concerts---jobsConcerts---jobs

Can you hear thisCan you hear this

Help of the DeafHelp of the Deaf ImplantsImplants Sign languageSign language Closed captioned Closed captioned

showsshows Use of light as Use of light as

alter devicesalter devices

Sign LanguageSign Language

Would You Rather? Would You Rather?

Lose your eyesight or hearing? Lose your eyesight or hearing? WHY?WHY?

Section 4Section 4

Other senses

Do you have food cravings?Do you have food cravings?

Do you have food cravings? Do you have food cravings?

Research suggest women are more likely to crave sweet foods with lots of fat such as chocolate.

Men are prone to crave foods high in protein and fat, such as burgers and lasagna.

Do you think food cravings are influenced by societal standards?

Chemical sensesChemical senses

SmellSmell Dogs have 7 times Dogs have 7 times

stronger sense of smell stronger sense of smell than humansthan humans

Without it could not taste Without it could not taste as much. as much.

Olfactory NerveOlfactory Nerve Adapts quicklyAdapts quickly

Locker roomLocker room PerfumePerfume SmokeSmoke Harmful fumesHarmful fumes

TasteTaste Dogs taste sweetness Dogs taste sweetness

cats can not.cats can not. 4 basic qualities4 basic qualities

SweetnessSweetness SaltinessSaltiness SournessSourness bitternessbitterness

The Taste BudsThe Taste Buds

1.1. BitterBitter

2.2. SourSour

3.3. SweetSweet

4.4. SaltySalty

The Skin SensesThe Skin SensesPressure Pressure TemperatureTemperature

Sensory receptors Sensory receptors fire when the skin is fire when the skin is touchedtouched

Fingertips, lips, nose Fingertips, lips, nose and cheeks are more and cheeks are more sensitivesensitive

Shoulders, thighs and Shoulders, thighs and calves less sensitive.calves less sensitive.

Is relativeIs relative Neurons just beneath Neurons just beneath

the skinthe skin Adapt to difference in Adapt to difference in

temperaturetemperature Pool waterPool water Going out into heat Going out into heat

from an air conditioned from an air conditioned building building

PainPain

Gate theoryGate theory A certain amount of information can be A certain amount of information can be

processed at a time. Rubbing/ scratching processed at a time. Rubbing/ scratching interrupts the pain messageinterrupts the pain message

Phantom limb painPhantom limb pain Pain in missing limbsPain in missing limbs Stored memories of missing limbStored memories of missing limb

PainPain

Video

Helen Keller

Section 5Section 5

Perception-Perception-The way we organize The way we organize

or make sense of or make sense of our sensory our sensory impressionsimpressions

ClosureClosure

Tendency to perceive a complete or whole Tendency to perceive a complete or whole figure even when there are gaps in what figure even when there are gaps in what your sense tell you.your sense tell you.

Figure ground perceptionFigure ground perception

Is the perception of Is the perception of figures against a figures against a background.background.

Look out a windowLook out a window People, dogs, cars, People, dogs, cars,

trees, houses on a trees, houses on a backgroundbackground

ProximityProximity

A presentation showing slide examples of the Gestalt Theory's principle of Proximity in different mediums of advertising, art and photography.

Gestalt Theory Principle: Proximity

Similarity- Similarity- people think of similar objects people think of similar objects belonging together.belonging together.

The rule of Continuity The rule of Continuity

The perceptual tendency to group stimuli The perceptual tendency to group stimuli into continuous patterns. into continuous patterns.

People prefer to see smooth continuous People prefer to see smooth continuous patterns not disrupted ones. patterns not disrupted ones.

Common FateCommon Fate

Things moving in the same direction are Things moving in the same direction are perceived as belonging together.perceived as belonging together.

Example: Group of runners people running Example: Group of runners people running together in the same direction would appear together in the same direction would appear to have the same purpose. to have the same purpose.

Visual Illusions

Illusions