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How to conduct an Eyetracking study
 

How to conduct an Eyetracking study

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  • This illustrates the brightpupileffect.
  • The computer thentakes the gaze data received and,usingsome kind of eyetracking software, saves it and maps it on the stimuli shown so you canseewhere your participantwaslooking.
  • ’Eye-mind hypothesis’ = what you look at is in mostcaseswhat you thinkabout. Onlysome of the eyemovements are concious – ”uncensored” data
  • Cornea = covers the front surface of the eyePupil = lets the light and visual information come into the eyeLens = focuses the light onto the retina that covers the back of the eye. Fovea = small, butveryimportant area on the retina.
  • The retina is covered by light receptor cells.Rod cells Doesn’trequiremuch light to workNot verygood at picking up contrast and coloursYou mostlysee in black and whitewhen you usethem. 94% of the ligth receptor cells found on the retina are rod cells.Cone cells Verygood at picking up colors and contrastsRequires a lot of light to work.Almost all of the cone cells are located in the foveaAlmost only by the fovea you seecolours and detailswhen you look around.
  • This is an illustration of the image seen by the eyes and sent to the brain.Only the foveal area can be seen clearly. The number of cone cells decreases the further away you get from the foveal areaParafoveal area = The area and just slightly outside of the foveal area. Still some cone cells, but less acuity than in the foveal area.Peripheral area = The area outside of the parafoveal area. The rod cells are more prominent in picking up light and the image is blurry and gray.The brain takes in information over time and mends it together into a coherent picture.
  • The area wesee with the fovea is about the size of a thumbnail at arms length.We are not blind outside of that area, but we don’t see as well.To take in details we need to place what we want to see on the foveal area and this is what the eye tracker measure.
  • Typical fixation frequency is < 3 Hz – meaning that you fixate at around three times pr. Second.
  • Remember to talk about the Area of Interest – which is what defines all the metrics…
  • We are nowgoing to look at a shortmovie to seehowwell your vision and brainworks.(Pause the clip after the guysays ’Buthow observant were you?’ Then ask ’Did you seeanythingstrange with this movie?’ Get the participants in the training to say the thingsthey’venoticed. Thenlet the clip finish. Point out that the reason for them not to havenoticed all the changes is that the brainonlytakes in small pieces of information and thenassumes that the rest stays the same. This is the same principle that magiciansuse to distract the audiencewhendoingtheir tricks. If you look at one hand, they are free to dosomethingelse with the other. (This is alsowhyeyewitnessesshouldn’t be trusted.) In eyetracking, this phenomenon is interesting as it highlights that unlesssomethingappearsimportant to look at, the brainwill make assumptionsinstead of actuallylooking at it. That is whyimportantthings on webpages for exampleoften are ignored – theydidn’tseem to be relevant by the pereferal vision and therefore not looked at using the fovea.)
  • Qualitative studies(formative research) Use eye tracking to 1. Detect usability problems2. Explain how usability problems occurred  Analysis usually done looking at individual gaze plots or heatmaps.. or film in slow-motion..Today we mostly going to look at the qualitative measures..
  • The so what question often appears if there are no bench marks, then the results can be hard to contextualize, and the most common response would then be .. Ok it took three seconds from first fixation till the respondent clicked on the target.. So what? Is it good or bad?
  • Two types of Quantitative studies:1: Measuring performance related differences(e.g.,. will the new design make it easier to find the relevant information? We are going to look at 4 great and interesting examples (Company information, pharmacists, GPS navigation in compare to competitors, instructions e.g.. from IKEA , how much mental workload do they require..)2: Measuring action related differences (different locations for a add on a homepage, which add design will create more interest,
  • Measuring attraction, is measuring how well a design support a business goal.. Do people see what we want them to see?
  • Which design draws more attention to a particular part of the website?
  • Noticability – A good measure to use is time to first fixation – because time is much more understandable for most people… than number of fixations
  • Which screen location will make adds more visible?Combining % of participants fixated on the ad, with time to first fixation…The percentage provides context… - not reporting the percentage would be misleading – as people would think that putting the add in the bottom of the page gave greater exposure..
  • Not so much about if some thing jumps out at you, but more about when you look at something, does maintain your interest…The cat doesn't’t jump out on you, but once you notice it, you kind of look at it, it something unexpected…% of time spent looking on AOI- with context of how long time that was out of the actual looking at the stimuli
  • AOI 1 - One type of cell phone descriptionAOI 2 – Another type of cell phone description..AOI 1 – gets noticed first, but doesn't’t get so much interest, AOI 2 get noticed later, but gets a lot of interest…Could be because this persons friend already had this phone, and therefore the person knew what he was going fore.. There are lot of different reasons for this…Noticability depends on the physical appearanceInterest depends on the content – once you look at it, is it the interesting…
  • Our pupil dilates when wee meet someone we know.. The same can be tracked with peoples reaction to things..
  • If it eg. Is a long session, peoples pupils might react to fatigue…and not to the design..
  • That why we sometimes se poker players with dark glasses..
  • Pupils gets larger as it gets darker, and smaller as it gest lighter – pupils are much more sensitive to light than to the reactions to different emotional response.. Therefore we need to control for this by having a fixed light setting – Good window blinds..Also the brightness of the stimuli has something to do with the pupil size.. So if the brightness of the different stimuli isnt equivalent, then pupil size shouldn't’t be measured…
  • High emotional arousal – means larger pupil size – but this can means both good and bad…Story with baby crying sounds.. This also made the pupils bigger, as do a pleasant experience..Therefore if the respondents pupils goes big, it might be because the are absolute offended with our design, and not because the really like it…Therefor other measures must be applied to determine if the experience was good or bad…
  • Different people have different pupil size and reacts different to different stimuli – everybody has a different baseline for their pupil size.. therefore people has to look at a neutral screen that has equal brightness as the stimuli – in order to “calibrate the pupil size…And therefore we have to look at changes to the persons pupil size in relation to their baseline
  • Measuring performance – is about how well a design helps users achieve their own goals.. We can measure Mental workloadCognitive processingTarget findabilityTarget recognizability
  • An example of measuring performance could be finding out whether redesign of an user interface has reduced workload, reduced cognitive processing, and made information easier to find and compare
  • Mental workload also effects pupil size, higher workload gives a bigger pupil size…I picture my self in a unfamiliar neighbor hood, its getting dark, its raining I'm trying to find my way, and then I get a phone call.. And I have a passenger that tells me to go higher..Could I possible get any higher mental workload?With a higher mental workload, the persons performance will suffer…
  • An example could be measuring - how a GPS effects mental workload…
  • Comparing two different manuals, and understanding how easy they where to understandAverage fixation durations is good to use here because, larger circles indicates longer fixations, and smaller circles indicates shorter fixation times…Longer fixations could be caused be things that are difficult to read and understand. Things like uncommon words gives longer fixations, higher information density like meditational packaging inserts with very little text..
  • The task here where, look for a certain generic information on the different medications The average fixation time for the new designed labels are much shorter than for the old labels, indicating that the new labels are much easier to read..
  • Average fixation time is different from dwell time.. Average fixation is the time of fixations divided by the number of fixationsTotal fixation is the times of fixations added togetherDwell time is the time of the total visits including saccades..
  • Locating means having one fixation on it, but not necessarily be sure that it’s the right thing you found..
  • Recognizing something is when you go – found it, knowing that this is my target, this is what I'm looking for..Proper search demands that you locate something, fixates and recognize it as what you are looking for..
  • This is stock photos, the participant already added a couple of photos to the cart, and know they need to go to the shopping basket..
  • This is what the participant looked at to find the target.. Going from left side of the screen to the right side of the screen, then fixation eleven sort of stopped at the target, but not recognizing the target and then back to the right side, and then fixation 16 when the user recognizes the target
  • So from fixation 1 to fixation 11 is findability
  • Measures how easy it is to locate the target..Number of fixations prior to fixation on targetNumber of fixations prior to fixation on targetTime to fixation on target..
  • Findability.. Dependent on layout, information architecture and things like this..
  • On second fixation on the target, the participant recognized the target, and clicked on it
  • Number of gaze visits before selection a lover number suggest that the target is easy to find, a higher number suggest that the target is hard to find..Or we could look at time from first fixation to selection on target. Where shorter time indicates better recocnizability than a longer time period…
  • This is a way of using the gazes and fixations for reporting the findability and recocnizabiliy of the target – Means that you have to look at something three times to realize that it is the shopping cart..
  • To bring togetherfindability and recocnizability – we can use a funnel like this..This is a motor oil company site, and the task was, find out which motor oil should be used for your car..So 71% looked at the target, but only 7% recocnized the target as the right link – so without eyetracking we would only have the 7% that found the target..Eyetracking helps us quantify the experience, only 7% clicked at the target, but 71% looked at the target..

How to conduct an Eyetracking study How to conduct an Eyetracking study Presentation Transcript

  • EYE TRACKINGHow and why?UXSTORIES.DK | 69
  • EYETRACKINGMAPPING OF DIFFERENT TYPES OF USER RESEARCH METHODS What do the user do? Why do the user do it?UXSTORIES.DK 2 | 69
  • SETTING UP A EYETRACKING STUDYTesting out our graphical designThere is a big difference in how the spectator looks at the actual message and Pampersbrand – depending on the way the baby looks at the spectator or at the Pampers messageUXSTORIES.DK 3 | 69
  • SETTING UP A EYETRACKING STUDYSUBHEADERSetting up a studie in the eyetracker…UXSTORIES.DK 4 | 69
  • HOW EYETRACKING WORKSThe bright pupil effectUXSTORIES.DK 5 | 69
  • HOW EYETRACKING WORKSPupil Centered Corneal ReflectionUXSTORIES.DK 6 | 69
  • HOW EYETRACKING WORKSTobii Eye trackersUXSTORIES.DK 7 | 69
  • HOW EYETRACKING WORKSWhat happens in the eyetracker?UXSTORIES.DK 8 | 69
  • HOW EYETRACKING WORKSWhat happens during the calibration?UXSTORIES.DK 9 | 69
  • HOW EYETRACKING WORKSWhat happens during the calibration? F (x) ( x, y) x11 x12 x13 (x, y) x21 x22 x23 x31 x32 x33UXSTORIES.DK 10 | 69
  • HOW EYETRACKING WORKSWhat happens after the calibration? •Gaze Data •t1; x1; y1; z1UXSTORIES.DK 11 | 69
  • HOW EYETRACKING WORKSWhat happens after the calibration? •Gaze Data •t1; x1; y1; z1UXSTORIES.DK 12 | 69
  • HOW OUR EYES WORKSOur eyes are the mirror of our soul(brain)UXSTORIES.DK 13 | 69
  • HOW OUR EYES WORKSHow our eyes are build.. •Retina •Pupil •Cornea •Fovea •LensUXSTORIES.DK 14 | 69
  • HOW OUR EYES WORKSHow our eyes are build.. •Light receptor cells •rod cells 94% •Cone cells 6%UXSTORIES.DK 15 | 69
  • HOW OUR EYES WORKSWhere do we focus?.UXSTORIES.DK 16 | 69
  • HOW OUR EYES WORKSWhat do we actual see?The human visual field = 220ºThe 1-2º area of foveal vision is about the size of athumbnail on an arm lengths distanceUXSTORIES.DK 17 | 69
  • HOW OUR EYES WORKSWhat do we actual see? The the foveal and parafoveal areas are less than 8% of the visual field but takes up over 50% of the visual cortex in the brain. Peripheral vision is mainly good at picking up movements and contrastsUXSTORIES.DK 18 | 69
  • HOW OUR EYES WORKS •Fixation •Saccade •The area of foveal visionUXSTORIES.DK 19 | 69
  • HOW OUR EYES WORKSFixations The fixation lengths varies from about 100 to 600 milliseconds, during this stop the brain starts to process the visual information received from the eyes. All the information from the scene is (mainly) acquired during fixations. Typical fixation frequency is < 3 Hz Common words get shorter fixations than less common words The length of a fixation is usually an indication of information processing or cognitive activities.UXSTORIES.DK 20 | 69
  • HOW OUR EYES WORKSFixationsUXSTORIES.DK 21 | 69
  • HOW OUR EYES WORKSSacades Saccades are extremely fast jumps from one fixation to the other and the average length of a saccade is about 20-40 ms When reading English the mean saccade size is 7-9 letter spaces Saccadic suppression: vision is largely suppressed during the movement The end point of saccade cannot be changed during the movement Regressive saccades and the saccade pattern can reveal confusion and problems understandingUXSTORIES.DK 22 | 69
  • HOW OUR EYES WORKSSacadesUXSTORIES.DK 23 | 69
  • HOW OUR EYES WORKSSUBHEADERUXSTORIES.DK 24 | 69
  • SETTING UP A EYETRACKING STUDYSetting up a study in the eyetracker…UXSTORIES.DK 25 | 69
  • ANALYZING DATAMany different possibilities for applying metricsAnalyzing data from the eye tracking study..UXSTORIES.DK 26 | 69
  • ANALYZING DATAMany different possibilities for applying metricsUXSTORIES.DK 27 | 69
  • ANALYZING DATAQualitative studies depends on defining areas of interest to analyse uponUXSTORIES.DK 28 | 69
  • ANALYZING DATATwo types of researchQuantitative studies(summative research)Use eye tracking to measure differences between designs(or design and benchmarks)When we use eye tracking to measure things - a lot of timeswe doing comparisons in the study as this enables us tomake certain decisions fx. which is a better design forachieving the purpose we want(and to avoid the so what?Question)UXSTORIES.DK 29 | 69
  • ANALYZING DATAMany different possibilities for applying metricsUXSTORIES.DK 30 | 69
  • ANALYZING DATA100 + Measures.. Statistics tab: there are 100+ measures.. Reaction 1: Whoa, measures Reaction 2: Yay, measures -> to many measures-> bloated reports-> confusion and dis interest Therefore be picky about the measures you chose, as the report else will be bloated and messy to read, and the take holders wont like that.(confusion & disinterest) Every measure has a meaning(or2 or 3) Different measures things can mean different in different contexts Therefore its important to know how the measures are calculated.. Chose measure with study type and research in mind!UXSTORIES.DK 31 | 69
  • ANALYZING DATAQuantitative studies Examples of measures: - Time to first Area of interest(AOI) fixation - Total number of fixations in the AOI - Visit count & visit duration per AOI - Average fixation duration Two types of Quantitative studies: 1: Measuring performance related differences(e.g.,. will the new design make it easier to find the relevant information? We are going to look at 4 great an interesting examples (Company information, pharmacists, GPS navigation in compare to competitors, instructions e.g.. from IKEA , how much mental workload do they require..) 2: Measuring action related differences (different locations for a add on a homepage, which add design will create more interest,UXSTORIES.DK 32 | 69
  • ANALYZING DATAQuantitative studies Decide whether it is a performance study or an attraction study.. For the different studys the same metrics can mean different things…UXSTORIES.DK 33 | 69
  • ANALYZING DATADifference between performance studies and attraction studies Q:If somebody looks at a thing a lot, and if there are a lot of fixations, what does this mean? Is it god or bad (confusion or interest)? A: It depends on the goal of the person that looks at the thing. Performance or attraction 1.Performance: Eg. package where person are to find the number of calories, then a lower number of fixations are god 2. Attraction: If the person studies an ad or a picture that you would like them to study, then a larger number of fixations are god.UXSTORIES.DK 34 | 69
  • ANALYZING DATAQuantitative studiesUXSTORIES.DK 35 | 69
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  • ANALYZING DATAQuantitative studiesUXSTORIES.DK 37 | 69
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  • ANALYZING DATAResources:Aka Boiko: Film about using KPI measures foreyetracking https://www.youtube.com/watch?v=Xp4pLOk_PtQJacob Nielsen: How to Conduct and Evaluate Usability Studies UsingEyetracking http://www.useit.com/eyetracking/methodology/eyetracking-methodology.pdfLaura Grant – how to make a good questionnaire(to be used when setting up the testdesign): http://www.lauragrantassociates.co.uk/Resources/Resources/24/how%20to%20design%20a%20good%20questionnaire.pdfTobii – homepage with different eyetracking cases andvideos: http://www.tobii.com/en/eye-tracking-research/global/research/usability/Tobii Studio eyetracking software download (to be used when analyzing on your owncomputer): http://studiohelp.tobii.org/Updates/UXSTORIES.DK 69 | 69