Eye Tracking as a Tool in Package and Shelf Testing

8/14/2019 Eye Tracking as a Tool in Package and Shelf Testing

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Tobii Technology

Eye tracking

as a tool

in packageand shelf testing

WhitePaper


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2 Eye tracking as a tool in package and shelf testingTobii Technology

Foreword

This guide is written to serve as inspiration and as an introduction for those who want to know more abouteye tracking and how this tool can be used in package and shelf testing. This guide will not explain amethodology but I hope it will inspire you to develop your own methodologies as well as your own tests and

experiments. I would also like to thank the people who have helped us with this guide, especially Poja Shams,who wrote the first draft of this guide. I would also like to thank Michel Wedel for providing feedback on thisdocument.

Tommy Strandvall([email protected])Tobii Technology

November 2008 / version 3 Tobii Technology ABStockholm, SwedenThis document can be downloaded from our website: www.tobii.com


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Table of Contents1. Introduction 4

1.1 What is eye tracking? 5

2. Eye tracking - a tool for shelf and package testing 52.1 What can eye tracking tell us about packages and products? 52.2 Designing a study 6

2.2.1 Uncontrolled tests 62.2.2. Controlled tests 7

2.3 Creating the stimuli 82.3.1 Creating the shelf images 82.3.2 Positioning and randomizing the products on the shelf 8

2.4 Conducting the study 92.4.1 How long should the products and the shelves be shown? 92.4.2 How many respondents should be included in the study? 92.4.3 Setting up and running the test 10

3. Visualizing and analyzing eye movement data 103.1 Visualizations in Tobii Studio 103.1.1 Gaze plots 103.1.2 Heat maps 113.1.3 Clusters 113.1.4 Areas of Interest (AOI) 11

3.2 Eye tracking metrics in Tobii Studio 113.3 Visualizing eye movement data in shelf tests by using Tobii Studio 13

Where did the eyes stop first? 13What is the average viewing pattern on the shelf? 14How many of the products on the shelf were noticed? 14Do shoppers see the product on the shelf? 15How many looked at the product first? 15Is the product able to pull attention quickly? 16How quickly did the product manage to pull attention? 16How much attention did the product get compared to competing products? 17How long was the product considered? 17How many times did the shoppers look at the product? 18How long does it take for the shoppers to find the product on the shelf? 18How long does it take to find and select a product on the shelf? 19How great is the products ability to retain attention for a period of time? 20Does the placement of the product on the shelf have an impact on the order in which theconsumers look at the products? 20How large is the attraction power for different elements in the design? 20

Bibliography 22


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1. Introduction

Most of our purchase decisions are made at the point of purchase, i.e. in the stores. According to the Point ofPurchase Advertising Institute, 74% of all mass merchandise purchase decisions are made in stores1

1POPAI (1997), Consumer Buying Habits Study

.

Additionally, our purchase decisions are usually very quick, as shoppers only spend a few seconds in front ofthe shelf before deciding to buy a specific product. Under these circumstances it is not surprising that theability for a product to attract shoppers visual attention i.e. to be seen - has a strong influence on thechoices they make products that are unseen are therefore often unsold.

Eye tracking equipment has been used in market research and for product testing over the past two decades.These studies have proved that eye tracking is a reliable way to measure attention given to objects likepackages on a shelf. By analyzing shoppers eye movements it is possible to gain insight into their visualattention span, which in turn is correlated with their purchase considerations.

Consumer behavior at the point of purchase is influenced by both memory-based and visual factors; eyetracking data is of course best suited for gaining insight in the visual factors that have an impact on purchasedecisions. The product packaging also affects the perception of the brand and the product and thus one

could say that the packaging is the product. The challenge for a product today is to break through the clutteron the shelf where many similar products and competing brands share the same space and where everyproduct is trying to attract the shoppers attention. For the product to be noticed, and ultimately purchased,the packaging must win when compared to competing packages and products. In this context, eye-trackingdata is especially good in revealing how well the package can break through on the shelf.

The three most common questions package research is trying to find an answer to are:

1) Package visibility and find ability on the shelf2) Image and brand communication3) Impact on the intention to buy and on sales

Package visibility is affected by several different factors such as shape, color, logo, etc. It is also possible to

test and compare alternative packages where the goal is to determine which design performs best on theshelf. Traditional methods such as recall are generally a poor measure of shelf visibility as it is impacted bybrand familiarity and memory rather than actual shelf visibility. This is why only asking consumers whichbrands they remember seeing on a shelf will most likely provide misleading answers.

Eye-tracking data is most valuable when it is combined with other conventional methods such as interviewswhere consumers are asked about their purchase intentions, brand loyalty, price sensitivity and purchasemotivation, etc.


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1.1 What is eye tracking?

An eye tracking system measures how the eyes typically move over a digital image that is shown to arespondent from the target group. The human eyes are constantly moving until they stop and focus on apoint. There are over ten different types of eye movements, of which the most important ones are saccades,fixations, and smooth pursuit. When the eyes stop to focus it is called a fixation and the movements betweenthese fixations are called saccades. The length of the stops, when the eye fixates, varies from about 100 to600 milliseconds and during this stop the brain starts to process the visual information received from theeyes2. Saccades are extremely fast jumps from one fixation to another. The average length of a saccade isabout 20-40 ms. During this period the eyes do not send visual information to the brain. The human eye hasa visual field of about 200 but the highest number of light sensitive cells on the retina are located in the partcalled fovea, which is the only point in our eyes where we are able to see a sharp and colorful image of theworld around us. This area is fairly small and covers only about 1 - 2 degrees of our vision (which is about thesize of a thumbnail at an arm lengths distance). It is only from these cells our brain can receive detailed visualinformation. Our perception is slightly larger than the area of foveal vision. When, for example, reading a text,we can read about 12-15 letters to the right and 3-4 letters to the left, which would indicate there is a

perceptual span of around 18 characters centered asymmetrically around the fixation point3

It is possible to move our covert attention (the attention of our mind) around the entire visual field when oureyes are at rest. Thus it is possible to move our attention around without eye movements. However, our fovealvision is usually a valid measure for determining the target of our covert attention as our brain can processvery little information from complex stimuli from the area outside the fovea (such as packages on a shelf).

. Using ourperipheral vision outside the area of the foveal vision we can see an unclear image, but our peripheral visionis generally very poor and is only good at picking up movements and contrasts.

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2. Eye tracking - a tool for shelf and package testing

Insuch cases it is more efficient for our brain to focus attention on the fovea rather than on our peripheralvision, as the brain needs to process blurry visual information requiring more effort to interpret than the visualinformation from the fovea. This is why it is possible to tell something about human behavior by just followingeye movements, especially the fixations, as we know that we can only see something clearly when we fixateon an object or are very close to it. If a person does not fixate on, or is not very close to the package on a

shelf, he or she would not be able to see the product and read the text on it. The eye tracker records thesemovements and the location of the foveal vision when the eyes fixate.

By analyzing our eye movements it is possible to tell something about our behavior. The length of a fixation isusually an indication of information processing or cognitive activities as this is when the brain interprets thevisual information from the eyes. For example, in reading studies it has been proven that for common wordsthe fixation lengths are shorter than for less common words where the fixation lengths are longer. Theamount of fixations can indicate how easy it is to find, for example, a specific package on a shelf. The fewerfixations used the more efficient the search process.

2.1 What can eye tracking tell us about packages and products?

Pre-testing and post-testing methods have traditionally been used to test the selling properties of a package.In pre-tests, focus groups, interviews, and questionnaires have been used to reveal the attitudes of shoppers.In post-tests, the quantity sold after changing the design is measured and compared to data collectedpreviously. In general, eye tracking is used as a tool to answer questions about the saliency of a package in astore environment. Saliency is an indicator of how well the package stands out compared to other packageson the shelf. An assumption in eye tracking studies is that packages that are viewed more have a highersaliency than products that are viewed less.

2

Rayner, K. (1998) Eye Movements in Reading and Information Processing: 20 Years of Research3Rayner, K. (1998) Eye Movements in Reading and Information Processing: 20 Years of Research4Pieters,. R & Wedel, M. (2007) Informativeness of eye movements for visual marketing: six cornerstones.


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When analyzing eye-tracking data from a shelf test the intention is usually to diagnose problems rather thanfinding specific designs that work well and could be used in other situations. In comparative studies newdesigns are tested against the current package. The data from an eye-tracking test are often combined withfocus groups, questionnaires and in-depth interviews to get a better understanding of how the package andthe product are perceived by shoppers. Other data that could be included are, for example, unaided shelfrecall, which can reveal which products the shoppers remember having seen on the shelf, or brand

consideration, which can reveal which brands on the shelf the shoppers would consider buying.

Consideration or purchase intention usually increases with the number of fixations on the product on theshelf. Noting a product is, however, not necessarily a direct indication of purchase intention as consumersusually note many more products on a shelf than they actually consider buying. In a shelf study conducted byThe Wharton School of Business they found a positive and significant correlation between how muchproducts were looked at (and reexamined) and purchase intention 5

2.2 Designing a study

. If the shopper looks at a product, looksaway and then looks back, the purchase intention increases. Evidence has also been put forward that purelymemory-based consideration is possible since unseen is not always unsold. There is, however, a strongpositive relationship between the number of fixations on a product and consideration, as products fixatedmore are more likely to be considered. Each fixation provides a new chance to consider the product and thusthere is a relationship between purchase intention and the number of fixations.

Products are of course considered even though they are not fixated on. This is because some packages andproducts are so well known that shoppers can even use their peripheral vision to identify them on the shelf, orthey simply expect that a well known product should be on the shelf. Additionally, attitudes towards thebrands play an important role when considering buying a product. Simply raising the visibility for brands thatpeople dislike, or for brands that are liked by everybody, does not necessarily increase the intention to buy theproduct.

The method used for a shelf test with eye tracking should be chosen based on which questions you want toanswer. To be able to answer some questions it is necessary to have an experimental design of the study tobe able to measure impact of, for example, design changes and placement. Eye tracking tests can generally

be designed in two ways, either as a controlled or an uncontrolled test. In an uncontrolled test, the purpose ofthe test is unknown to the respondents. The respondent is only instructed to look at the shelf, or the image ofthe shelf, without any specific instructions. The main purpose of an uncontrolled test is to measure thegeneral saliency of the products on the shelf. In a controlled test the respondent is given a set of instructions,for example to choose a product or to look for certain products, product properties, or product attributes. Themain purpose of a controlled test is to observe the performance of the tasks, for example measuring howlong it took to find a certain package on the shelf.

Regardless of the design you choose, you should always include questionnaires or interviews to gain moreinformation on the behavior of the respondents. These questions are not covered by this guide.

2.2.1 Uncontrolled tests

The performance indicator in an uncontrolled test is the time the respondents spend looking at differentproducts. The viewing time, during which time the shelf is shown, can either be constant or variabledepending on how the test is constructed. If you have the same viewing time for every respondent, theobservation times for different products are directly comparable between the respondents. However, if yougive the respondent the possibility to control the viewing time (this is called a relative measurement), theobservation times are not directly comparable. However, it is possible to see how big the attraction power isfor the different products and the shelf. A tachistoscope method can also be employed in uncontrolled tests;in this case the shelf is shown for a very short time, for example 0.5 seconds, after which the respondents areasked to mention which products they remember seeing on the shelf. The test can then be repeated with alonger viewing time of, for example, 3 seconds. An uncontrolled test should always have a predeterminedrandomization of the tested product on the shelf. Respondents tend to focus on the center of the shelf during

5Chandon, Hutchinson, Bradlow and Young (2007) Measuring the Value of Point-of-Purchase Marketing with Commercial Eye-Tracking Data


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an uncontrolled test and therefore it is important to randomize the tested products in different placements onthe shelf to minimize the effect of the position.

Example questions in uncontrolled tests Do shoppers see the product on the shelf? How long does it take for the shopper to see the product? How much attention did the product get compared to competing products? Do shoppers see the product before they see the competing products? Does the placement of the product on the shelf have an impact on the duration or order in which the

shopper looks at the product?

2.2.2. Controlled tests

In controlled tests the indicators of performance are generated from instructions and tasks given to therespondents. Examples of such tasks are; to look for a certain product (brand A), or a product category(cookie), or product attributes (blue color and cylindrical shape), or a product property (everyday cookie).Instructing respondents to imagine that they need to buy a product and then asking them which product they

would consider buying will provide you with both eye tracking data and brand consideration data. Theperformance results are based on how the respondents conducted these tasks, such as time spentsearching, choices they made, etc. Process-based results are the eye movements that occurred whileconducting the tasks, for example what they were looking at and for how long, which elements on thepackage they looked at, etc.

An important aspect of process-based data is that the quantity of time spent looking at a certain product onthe shelf does not automatically mean that the shopper will buy the product. However, it will give you insightinto the decision-making process of the respondent and reveal if the product is considered as an option forpurchase.

The tasks in controlled tests can be anything from perceptual features such as; finding the most exclusiveproduct on the shelf or looking for light products on the soda shelf to conceptual features like finding cookies

on the shelf or finding Brand A cookies on the shelf. The perceptual features are connected to theperceptions of the products and the brand. As an example, luxury, economical, and inexpensive areperceptual features. Perceptual features are used to see if the packaging is communicating the message it issupposed to communicate. Conceptual features are connected to the long-term memory and can be seen asthe mental picture of a product, brand or category. Brand A is a conceptual feature, which is connected to themental picture of Brand A in the mind of the respondent.

Example questions in controlled tests How long does it take for the shopper to find the product on the shelf? Can we change the time needed to find the product on the shelf by changing different properties

(color, shape, glossiness) of the packaging?

How much attention does a package get when the shopper is looking for a product with certainproperties, for example an exclusive product? Which products in the same product category are seen as having a certain property, for example

being exclusive? What attributes do other products with the same property have and how can these be used in a new

design?

ExampleSuppose a respondent is asked to find Brand A cookies on a shelf and to click on the product with themouse when it is found. The performance is the time it takes for the respondent to find and click on theBrand A product. The process consists of the eye movements during this time. Some interesting questions toanswer are: How long does it take for the average respondent to find Brand A? What products were

confused with Brand A and contributed to the delay of finding Brand A?


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How do we use this information? If Brand A needs to differentiate the package design but still keep thefeeling of Brand A while raising the find ability level, then the results can reveal design details thatcommunicate Brand A to the shopper. When the essence of the Brand A design is found we can manipulatethe package to enhance these communicative properties. The details that communicate Brand A may be anyattributes on the package such as the color, shape, glossiness, brand name and font. Eye tracking can beused as a tool to help you find these details. In this case, the question we want to answer might be; what was

the first point on the package the respondents looked at when identifying it as Brand A?

2.3 Creating the stimuli

2.3.1 Creating the shelf images

It is important to use good quality images in a shelf test. Details that can grab attention and are not related tothe products should not be present. If it is important to also include price as a factor in the test, then pricetags can be included on the shelf. There are three main ways to create the picture of the shelf; using a virtualplanogram, photographing the products on a real shelf or photographing the products one by one in a lightbox and then composing a shelf out of the images. If you are photographing a real shelf then randomizing

products on the shelf can be time consuming and there might also be problems with the quality of the image.Photographing the products one by one and using photo-editing software to create the virtual shelf mightresult in better quality. Additionally, it is easy to make changes to the shelf using this method, for examplewhen changing the positions of the products. Another aspect of this method is that all the products will havethe same face angle. If the face angle is the same for all the products on the shelf, the products on the lowershelf level will be seen from the same angle as the products in the middle and the top. The advantage is thatno bias will be present on any part of the shelf. The disadvantage is that the picture will be unrealistic forrespondents who notice this visual glitch. 3D modeling software can also be used to create more realisticpictures of the shelf or the products.

2.3.2 Positioning and randomizing the products on the shelf

If the test is uncontrolled, it is important to randomize the products on the shelf since the attention of therespondents tends to focus around the center of the picture. Randomizing the positions on the shelf willremove this bias. The positions used on the shelf should follow the logic for how real products are placed onshelves in stores. This logic is based on brands, products, and sometimes the product quality. Randomizationwill give a better understanding of how the position of the products affects the results. By randomizing theproducts you can observe if the product gets the same amount of attention independent of position on theshelf. To be able to compare whether or not the position has an impact one would typically show the picturesto two different groups of similar people; one group would see the product in position A and one group wouldsee the product in position B (see image below).

If the test is controlled, it is not recommended that you randomize the positions because the purpose is tomeasure the attention based on instructions given to the respondents. In more complex studies where, forexample, you want to measure the impact of design changes, it is necessary to use an experimental design of

your study and to carefully randomize the positions of the packages on the shelf.


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Group A Group B

2.4 Conducting the study

2.4.1 How long should the products and the shelves be shown?

Shoppers typically make their purchasing decisions in front of the shelf within only a few seconds. A shopperspends on average of 10 seconds on a product category before approaching a certain part of the shelf. 6 In arecent eye tracking study7

2.4.2 How many respondents should be included in the study?

involving 309 shoppers where the respondents were asked to look at a picture ofa shelf of detergents and juices for as long as they wanted in order to make a purchase decision, the averageviewing time for the detergents turned out to be 17.99 seconds, and for juices 25.06 seconds. Other in-storeobservation studies have revealed that shoppers spend between 12.2 and 13.2 seconds in front of a shelfwith detergents.

Deciding how long the shelf should be shown to the respondents depends on the type of test you areconducting and the number of products on the shelf. If the test is uncontrolled you can show every shelf for afixed time. In controlled tests the viewing time should stop when the respondent has fulfilled the task. Inuncontrolled tests, the suggested viewing time for small shelves could be about 3 to 7 seconds, and for largershelves with more products, up to 15 or 20 seconds. It is also possible to let the respondents decide

themselves how long they want to view the image of the shelf. By doing this it is possible measure how wellthe packages manage to engage the respondents and hold their attention. In tachistoscope tests (T-scope),the image of the package or the shelf is shown very quickly to the respondents. The viewing time can beparts of a second up to a few seconds. Usually the viewing time is gradually increased (for example 0.5, 3and 7 seconds) to measure how the recognition improves. In these T-scope studies the respondents areasked directly after the viewing to recall what they have seen on the shelf.

A general rule when deciding how many people to include in the study is that the test should always beconducted among people who are in the target group for the brand or the product category. The sample sizeto be used in a shelf-test with eye tracking depends on three main factors: 1) the sub-groups that will be

analyzed independently; 2) the degree of risk involved in the decisions being made based on the results; and3) the amount of available resources, mainly time and money. In the Tobii Studio software you can usedemographic variables such as age, gender, and income level to filter the results. If you want to be able tocompare the results based on different background variables you need to include enough people from eachsub-group or cell in the study to get reliable results that can be generalized to the entire population. If you areplanning to use statistical tests on the results, for example, to find correlations, you need to adapt the numberof respondents to the type of statistical tests you are planning to conduct. In commercial shelf tests with eyetracking, a sample size of about 100 per cell is usually used to get robust and reliable data. For example, if itis important to compare men and women independently then it is advisable to have about 100 from eachgroup in the study. Tests can of course also be conducted with fewer participants, depending on the goalsand available resources.

6 Rowan, Claire (2000), Packaging by design, Food engineering International, February7 Chandon, Hutchinson, Bradlow and Young (2007)Measuring the Value of Point-of-Purchase Marketing with Commercial Eye-TrackingData

Compare

Compare


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70 cm

27

2.4.3 Setting up and running the test

Using a Tobii x120 eye trackerThe Tobii x120 eye tracker is most suitable for shelf testing as itcan be used together with life-size shelf images projected on ascreen or shown on a large monitor. When used together with aprojector and a screen the respondent should stand or sit a coupleof meters away from the screen, depending on the size of thescreen. The eye tracker itself should be placed at a distance ofabout 70 cm (27.5) from the respondents eyes. The eye-trackershould be attached to a robust floor stand and the height and tiltshould be adjusted so the eye tracker is able to track therespondents eyes regardless of where on the screen therespondent is looking. We recommend using the Tobii floor standwhere the height is easily adjusted. A good high definition projectorand a high quality screen should also be used for maximum quality.When deciding the size of the screen and the distance from the screen to the respondent, please calculate

the correct distance and size based on the maximum viewing angle of the eye tracker, which is 35 degrees(see image below). For smaller shelves (not life-size) a large monitor or television screen can be used topresent the images to the respondents. For more information about how to use the Tobii x120 together witha projector and a screen please refer to the x120 User Manual.

If the Tobii x120 eye tracker is used together with a scene camera, a real shelf with real products could beused in the test. In this case the setup would be similar to the setup above, but instead, a real shelf with realproducts would be presented to the respondent. In this setup a video camera needs to be placed close to therespondent so it can record the entire shelf during the test. Viewing time can be controlled by covering theshelf using a roll-up screen. Additionally, the same roll-up screen can be used when conducting thecalibration. Using a setup with a real shelf is complicated and the quality of the results might also be affected,especially since the resolution of the images will be much lower as they are taken directly from the videocamera. For more information on how to use the x120 in a scene camera setup please refer to the Tobii

x120 User manual.

Using a Tobii T60 or T120 eye trackerFor testing small shelves or individual packages, a Tobii T60 or T120 eye tracker can be used. In this casethe stimulus is shown on the integrated 17 TFT screen with a resolution of maximum 1280 x 1024. Whenusing a Tobii T60/T120 the respondent can either sit or stand in front of the eye tracker. The distance fromthe respondents eyes to the eye tracker should be around 70 cm (27.5).

3. Visualizing and analyzing eyemovement data

3.1 Visualizations in Tobii Studio

After collecting the eye movement data it is time to analyze theresults. This is done in the Visualization view in the Tobii Studiosoftware package.

3.1.1 Gaze plots

The Gaze Plot tool in Tobii Studio is a useful tool when visualizingscan paths and search behavior. Each fixation is illustrated with a

dot where the radius represents the length of the fixation. Thelonger the fixation - the larger the dot. It is recommended that youuse the gaze plot for only one or a few participants since the plots


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will be hard to interpret if more people are included. The scan path image helpful when drawing conclusionson the search behavior of the individual participants. By decreasing the time being shown in a gaze plot it ispossible to create illustrative images representing a short time interval, such as the eye movements duringthe first 0.5 seconds when the shelf was shown.

3.1.2 Heat maps

The Heat Map plot is a powerful way to visualize the gaze behaviorof an entire group of recordings. The Heat Map plot consists of theshelf picture as background image and a Heat Map masksuperimposed on top of this. It shows the aggregated results ofmany respondents as hot and cold spots on the shelf picture or asa gaze opacity picture where the fixations create holes in anotherwise black surface. A heat map can be created based eitheron the fixation count or fixation duration. It is possible to set thescale for the heat map when creating a heat map based on fixationcount or absolute duration. You can easily see whether theaverage respondent has seen a part of the shelf or not by looking at a heat map. By decreasing the time

being shown in a heat map it is possible to create illustrative images representing a short time interval, suchas the eye movements during the first 0.5 seconds when the shelf was shown.

3.1.3 Clusters

Clustering of fixation data can be seen as an automatic generationof Areas of Interest. The cluster function reveals areas with a highconcentration of fixation points. The maximum distance betweenfixations to include in a cluster can be set as a distance threshold inthe settings.

3.1.4 Areas of Interest (AOI)

A very useful tool for quantifying gaze data on a higher level is touse areas of interest (AOI). You can draw the areas of interest onyour shelf image, and after this, the gaze data from these areas areavailable for further statistical analysis in Tobii Studio or othersoftware. The data for the different AOIs can easily be exported forfurther analysis by using the built-in SPSS export function in TobiiStudio. The AOI should be slightly larger than the exact graphicalobject you want to analyze; this is because you also want to pick upfixations that are not completely on target due to the inaccuracy ofhuman vision.

3.2 Eye tracking metrics in Tobii Studio

All the eye tracking metrics included in Tobii Studio are affected by the fixationfilters, which are used for defining fixations and cleaning up the gaze data. Bychanging the settings for the fixation filters the results will vary since the ideabehind the fixation filters is to reduce the amount of data by combining individualfixations into groups of fixations and thus reduce the amount of data. In turn, theduration of the fixations will be longer.

There are two different ways of presenting the gaze data for the different Areas ofInterest (AOI) defined in Tobii Studio; either as results for the different individual participants(recordings/participants versus AOIs) or as averages over all participants (Images versus AOIs). As a default,the values presented for the individual participants are sums of the gaze data within the respective AOIs. Thevalues presented for all the participants (Images versus AOIs) are averages over all participants for the


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different AOIs. By using the Cell values button in Studio, it is possible to get other values such as averagesfor individuals.

The following metrics are currently included in Tobii Studio:

Time to first fixationThe time in seconds from when the stimulus was shown until the start of the first fixation within an AOI.

Fixation lengthThe length of the fixations in seconds within an AOI.


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Fixation countThe number of fixations within an AOI.

Observation lengthThe total time in seconds for every time a person has looked within an AOI, starting with a fixation inside theAOI and ending with a fixation outside the AOI.

Observation countThe number of visits and re-visits to an AOI.

Fixations beforeThe number of fixations before the participant fixated within an AOI for the first time.

Participant %The percentage of participants that have fixated at least once within an AOI.

Exporting data for further analysisUsing Tobii Studio you can compare groups based on background variables by filtering the results to onlyshow the results for a specific sub-group. For example, if you want to search for significant differences

between groups you need to export the gaze data from Tobii Studio and analyze it using other software.There is an integrated SPSS/Mathlab/Excel export function in Tobii Studio that will export the data fordifferent AOIs to a text file. It is also possible to export raw gaze data for every participant separately by usingthe Text Export function found in the Replay view.

3.3 Visualizing eye movement data in shelf tests by using TobiiStudio

Where did the eyes stop first?By looking at the fixations in a gaze plot you will see where the respondents fixated during the test. On the

timeline you can define the time interval to be displayed, for example the first few fixations on the shelf. If younotice that the first fixation is interfered with by the previous stimuli shown, we recommend starting the gazeplot analysis at the second fixation. It is possible to save the selected time on the timeline and then generatea heat map or a gaze opacity heat map for the same time interval to illustrate what caught the respondentsattention when they first saw the shelf.


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A Gaze opacity heat map and a gaze plot showing the attention during the first second.

What is the average viewing pattern on the shelf?If you want to reveal the respondents average viewing pattern you can use the Time to First fixationmetricfor your AOIs. The simplest way to get a basic illustration of the viewing pattern is to analyze which AOI hasthe shortest average Time to First fixation, second shortest, etc. In the Table view in Tobii Studio you canorganize the values in the Time to First Fixation column to get a list of the average viewing order of the AOIs.For a more robust analysis of the viewing order you need to export the AOI data for the individualrespondents and do the analysis as illustrated below. In this case you will be able to calculate the percentageof people that have seen the AOI in a certain order.

Time To First Fixation Product X Product Y Product X order Product Y orderPerson A 0.45 1.10 1 2Person B 0.80 0.45 2 1Person C 1.35 0.65 2 1Person D 0.75 0.55 2 1

Product X Product Y1st 25% 75%2nd 75% 25%

How many of the products on the shelf were noticed?By defining an AOI around all the products on the shelf it is possible to compare the attraction power for all

of them. Use the function Participant % in Tobii Studio to see how many of the respondents noted thedifferent products on the shelf i.e. fixated at least once within the defined AOI.

The average Time to First Fixation values for the Areas of Interest defined on the shelf displayed as agraph and as a table in Tobii Studio.


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Do shoppers see the product on the shelf?The fastest way to analyze whether or not the respondents have seen the product on the shelf is to make aheat map including data for all respondents. If there is attention on the product you can compare it to otherproducts on the shelf by creating an AOI around the products. After this, you are able to use the metricParticipant %in Tobii Studio, which will reveal what percentage of the respondents looked at the product onthe shelf at least once.

How many looked at the product first?If you want to find out how quickly the products managed to attract attention you can calculate whatpercentage of the respondents looked first at a product. This is done in Tobii Studio by selecting Time toFirst fixation andthen going to the Table view and comparing the individual results for all participants. Count

how many people have the shortest time for Product 1 and the shortest time for Product 2 and then generatethe percentage. For example, in this case 21 out of 25 respondents first looked at Product 1 resulting in84%.

The graph shows the percentage of respondents that have fixated at least once within the definedAOIs.

A heat map reveals if there is attention on the products. By using Participant % you can compare howmuch the different products on the shelf were seen.

A Gaze plot showing only the first second can reveal what the respondents looked at first. By using Timeto First fixation and the table view you can reveal which products received more first looks.


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Is the product able to pull attention quickly?By looking at the fixations in a gaze plotyou will see how the respondents are fixating and moving their eyesover the shelf. For example, by changing the time interval being shown you can manipulate the gaze plotimage to show results for the first second or only the first few fixations. We recommend starting the gaze plot

analysis at the second fixation if the first fixation is affected by the previous image shown.

By using the metric Time to First Fixation in Tobii Studio you will be able to see how quickly the differentAOIs were seen in seconds. The lower the average Time to First Fixation for an AOI, the quicker it has beendetected.

How quickly did the product manage to pull attention?

By using the timeline in Tobii Studio you can choose to only view results for a certain time interval. Use theParticipant % in combination with the timeline to see how many participants looked at the product withindifferent time frames; for example, within 1 second, within 2 seconds and within 5 seconds, etc. This is anindicator of the time it took for an element or a product to pull attention.

1 second, Participant % 2 seconds, Participant % 5 seconds, Participant %

A Gaze plot showing only the first second or the first few seconds can reveal what the respondents looked at first.By looking at the graph for Time to First fixation you can reveal which product had the quickest average Time toFirst Fixation.


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How much attention did the product get compared to competingproducts?By defining an AOI around the products you can compare the differences between the products. You cancompare the amount of attention they received by looking at metrics like Observation count, Observation

length, Fixation lengthor Fixation countin Tobii Studio.

How long was the product considered?The length of time the respondents looked at the product or a design element indicates the level ofinvolvement with the product. This is measured in Tobii Studio by using the metric Observation lengthorFixation length. Observation length will show you in seconds how much time the respondents on averagespent looking within an AOI.

For example, compare the different products on the shelf using AOIs and the metric Observation Length.


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How many times did the shoppers look at the product?

By looking at Observation count in Tobii Studio you are able to see, on average, how many times therespondents looked at the products within the AOIs. For example, by analyzing the values in the Table view inTobii Studio for every individual separately you can also manually generate a percentage describing howmany times the respondents re-examined a product at least once.

How long does it take for the shoppers to find the product on the shelf?The products find ability is revealed by looking at the time it takes to find the product on the shelf. Bymeasuring the time it takes for the respondents to find or fixate on the product you get a find ability score. InTobii Studio this could be done by measuring Time to first fixation. If there are different designs available forthe same product, you can use different groups of respondents to compare whether there are anydifferences in find ability between the different designs.

By comparing Observation Length you will see, on average, how many seconds the respondents spent looking atthe different products.

The metric Observation Count will reveal howmany times, on average, an AOI was visited andre-visited. In the table view you are able to see thevalues for the individual respondents.


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How long does it take to find and select a product on the shelf?By having the participants click on the product they would like to purchase, or that they are asked to find on

the shelf, you can gain insight into how long it takes to find a specific product. The clicks on products arevisualized in both heat maps and gaze plots. When analyzing individual respondents in the Replay view inStudio you will be able to see how long it took until a person clicked on the product in the Events window.Every click or key press has a time stamp. You may also see the click as an event on the timeline in theReplay view. Another way of getting the data is by using the Bee Swarm function in Tobii Studio. In this casethe viewing time for an image must have been set to end when clicking on the image. Select the image youwant to analyze, then right-click on the timeline and choose Copy Activity Data to Clipboard. The data willshow how long every participant has seen the image, i.e. how long it took until they clicked on the product.When you have all the time-to-click values for every respondent, calculate averages, maximum, minimum andstandard deviation for the find ability (time-to-click). You may also combine the time-to-click values with Timeto First fixationto see whether there is a difference between these two values.

Time to First fixation will reveal the average of how long it took for the respondents to find the product on the shelf.

Clicks are visualized in heat maps in Tobii Studio. Tocalculate the time-to-click rates you can calculate thetime difference between the ImageStart event and theLeftMouseClick event.


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By using the Cluster tool in Tobii Studio it is possible to findclusters of fixations on the shelf. For example, by using thisfunction you can reveal design elements that attract plenty offixations. Changing the Distance threshold under Settings willhave an impact on the size of the clusters. The clusters can be

exported as AOIs for further analysis.

By comparing the Participant % values for different AOIs you can find out which design elements were seen.


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Bibliography

Chandon, P., Hutchinson, W., Bradlow, E., & Young, S. (2008). Measuring the Value of Point-of-Purchase

Marketing with Commercial Eye-Tracking Data. In Wedel, M. & Pieters, R. (Eds.), Visual Marketing: FromAttention to Action. New York: Lawrence Earlbaum

Oshima, V. (2004). Are you being seen? Being visible in the cluttered marketing space of Asia. Paperpresented at ESOMARs Asia Pacific Conference March 2004, Shanghai, China.

Pieters,. R & Wedel, M. (2008). Informativeness of eye movements for visual marketing: six cornerstones. InWedel, M. & Pieters, R. (Eds.), Visual Marketing: From Attention to Action. New York: Lawrence Earlbaum

Rayner, K. (1998). Eye Movements in Reading and Information Processing: 20 Years of Research.Psychological Bulletin, 124, 372-422.

Rowan, Claire (2000). Packaging by design, Food engineering International, February.

Russo, E., & Leclerc, F. (1994). An Eye-Fixation Analysis of Choice Processes for Consumer Nondurables.The Journal of Consumer Research, Vol. 21, No. 2. pp. 274-290

Stingo, R. & Gallucci, F. (2007). Biofeedback and eye-tracking the emotional and cognitive experience instore.

Van der Lans, R., Peters, R. & Wedel, M. (2008). Competitive Brand Salience. Marketing Science, 27: 922 -931.

Wedel, M. and Pieters, R. (2008) Eye Tracking for Visual Marketing. Foundations and Trends in Marketing, Vol.1: No 4, pp 231-320.

Wedel, M. & Pieters, R. (Eds.) (2008) Visual Marketing: From Attention to Action. New York: LawrenceEarlbaum

Documents

Eye Tracking as a Tool in Package and Shelf Testing