Research Article Evaluation of a Navigation Radio Using the Think-Aloud Method - Hindawi

13 Pages·2015·3.39 MB·English

HindawiPublishingCorporation
InternationalJournalofVehicularTechnology
Volume2013,ArticleID705086,12pages
http://dx.doi.org/10.1155/2013/705086
Research Article
Evaluation of a Navigation Radio Using the Think-Aloud Method
PaulA.Green1andJin-SeopPark2
1DriverInterfaceGroup,UniversityofMichiganTransportationResearchInstitute,2901BaxterRoad,AnnArbor,
MI48109-2150,USA
2AdvancedVehicleSafetyandDynamicsResearchOffice,KoreaAutomobileTestingandResearchInstitute,
200Samjon-ro,Songsan-myeon,Hwaseong-si,Gyeonggi-do445-871,RepublicofKorea
CorrespondenceshouldbeaddressedtoPaulA.Green;[email protected]
Received10October2012;Accepted26December2012
AcademicEditor:MotoyukiAkamatsu
Copyright©2013P.A.GreenandJ.-S.Park.isisanopenaccessarticledistributedundertheCreativeCommonsAttribution
License,whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperly
cited.
Inthisexperiment,13licenseddriversperformed20taskswithaprototypenavigationradio.Subjectscompletedsuchtasksas
enteringastreetaddress,selectingapresetradiostation,andtuningtoanXMstationwhile“thinkingaloud”toidentifyproblems
withoperatingtheprototypeinterface.Overall,subjectsidenti�ed64uniqueproblemswiththeinterface;17speci�cproblems
wereencounteredbymorethanhalfofthesubjects.Problemsarerelatedtoinconsistentmusicinterfaces,limitationstodestination
entrymethods,iconsthatwerenotunderstood,thelackoffunctionalgrouping,andsimilarlookingbuttonsanddisplays,among
others.Animportantprojectfocuswasgettingthe�ndingstothedevelopersquickly.Havingascribetocodeinteractionsinreal
timehelpedaswellasdirectedobservationsoftestsessionsbyrepresentativesofthedevelopers.Otherresearchersareencouraged
tousethismethodtoexamineautomotiveinterfacesasacomplementtotraditionalusabilitytesting.
1.Introduction Consequently, there has been considerable interest in
predicting user performance, in particular task time [17–
People want products that are easy to use, and that is
22]. Task times for experienced users can be predicted in a
partic-ularly true of motor vehicles. Numerous methods
fractionofthetimetoplan,conduct,andanalyzeausability
have been developed to assess the ease of use of driver
test. If the method used by subjects to perform a task is
interfaces, both traditionally, and more recently from the
known,thepredictionsshouldbeasaccurateastheusability
human-computerinteractionliterature[1–3].ethreemost
testdata[23].
prominentmethodsare(1)usabilitytesting[4–8],(2)expert
Expertreviewscanbeanefficientalternativetousability
reviews [9–11], and (3) the think-aloud method [12–15].
testing,especiallyearlyindesign,thoughtheymaybeused
Methodsvaryintermsoftheirvalueforformativeevaluation
forsummativetestingaswell.Inanexpertreview,eachstepof
(whiledevelopmentisinprogress)andsummativeevaluation
eachtaskisexaminedtodeterminehowtheinterfaceshould
(at the end of development). See [16] for an extensive
be designed according to established usability heuristics
overviewofhowvariousmethodsareconductedandwhere
and guidelines. Expert reviews are oen criticized as being
theyshouldbeapplied.
“just someone’s opinion.” erefore, reviewers should be
Usability testing is the gold standard of usability test
professionally certi�ed in human factors or usability. (See
methods, as it involves real users performing real tasks,
http://www.bcpe.org/).
thoughoeninalaboratorysetting,andcanbepartofeither
formativeorsummativetesting.epurposeistodetermine Inthethink-aloudmethod,usersdescribetheirlogicas
taskcompletiontimesanderrors.Generally,usabilitytesting they try to use an interface. For example, a subject might
occursinthelatterstagesofdesign,whenafullyfunctioning say, “I selected the city name but cannot �gure out how
interface is available. Usability tests are time-consuming to to get to the next step,” or “Sometimes, there is an OK
planandanalyzeandcanbecostly. button in the lower right corner, but there is not one here.
2 InternationalJournalofVehicularTechnology
F1:Mostcommonscreen. F3:XMradioscreen.
F2:Oneoftwodestinationscreens. F4:Listofpreviousdestinationsscreen.
I am stuck and frustrated.” e think-aloud method helps usefultothesponsor,theexperienceoftheresearchteam,the
evaluatorsidentifywhatisconfusingormisleadingandhow fundingfortheproject,theschedule,andotherfactors.ere
thoseproblemscanberesolved.Ifsubjectsfallsilent,thenthe wasextremepressuretocompletethisprojectveryquicklyto
experimenterpromptsthemtospeakbutneedstodowithout meettheproductionschedulesetbyHyundai-Kia.erefore,
interferingwiththesubject�sthinkingprocessorin�uencing considerable thought was given as to how to complete this
them.Whentopromptandwhattosayismuchmoredifficult project quickly, which meant that less time was spent on
to do than it may seem. In fact, considerable experimenter certainactivitiesthanisideal,andmethodstoacceleratedata
trainingandpracticearerequired.See[16]foradiscussion. collectionandanalysiswereexplored.
ink-aloudevaluationsaremostusefulduringtheearly
stages of design while the design is still being formu- 2.Method
lated, identifying problems users experience more readily
than other methods. Unfortunately, as is described later, 2.1.NavigationDeviceExamined. edeviceexaminedwas
data reduction in think-aloud evaluations is very time- an early working prototype of a Mobis generation 3 nav-
consuming. igation radio. As shown in Figure 1, the navigation radio
Recently, the authors conducted an evaluation of an consistedofanLCDdisplaysurroundedby10hardbuttons
earlyprototypeoftheMobisGeneration3navigationradio (e.g., select satellite radio, seek), two CD related buttons, a
for Hyundai-Kia vehicles [24]. e complete experiment volumeknob,andatuningknob.esehardbuttonsaswell
included four parts (1) a think-aloud evaluation from a assobuttonsonthetouchscreenallowedaccesstohundreds
humanfactorsexpert,(2)athink-aloudevaluationinvolving ofscreens.Figures2,3,and4showexamplescreens.
13 ordinary drivers, (3) a follow-up survey of those drivers
primarily concerning their understanding of icons, and 2.2. Test Facility. e experiment was performed using the
(4)estimatesoftasktimesperSAERecommendedPractice third generation UMTRI driving simulator while “parked.”
J2365 [20]. Because this experiment was conducted during enavigationsystemwasmountedintothecenterstackof
theearlystageofinterfacedesign,andtheinterfacedesigners thesimulatorcab.Toenablesignalreceptionanduseofthe
needed to know what problems users would encounter, the GPSandXMfunctions,anantennawasinstalled,connecting
focusoftheexperimentandthispaperconcernsonlypart2, thesimulatorlabwithanoutsideroom.Figures5and6show
thethink-aloudevaluationbyordinarydrivers. a hypothetical subject being recorded, the equipment used,
ere are many other ways this data could have been andtherecordedimagefromanactualsubject.Althoughthe
collected. For example, questions concerning what subjects cameras were in plain sight, subjects ignored them, in part
did and what subjects did and why, could have been asked becausethecamerainfrontofthemwassmall.
retrospectively. In selecting methods to utilize, the authors
considered the speci�cs of the request for quote from the 2.3.SequenceofTasksintheExperiment. Ineachsession,one
sponsor,verifyingconformancetoacceptedindustrypractice sessionpersubject,subjects(1)completedbiographicaland
(e.g.,SAEJ2365),whatinformationwasbelievedtobemost consentformsandhadtheirvisionchecked,(2)practicedthe
InternationalJournalofVehicularTechnology 3
testingofthe�rstauthor,whichledtodiscussionsofwhen
Panasonic SV-BP314 camera
topromptandwhattosay.esecondauthoralsoobserved
aimed at navigation radio
andprovidedfeedbackontestsessionsofthe�rstfewsubjects
aer each session was complete. Ideally, more time would
havebeendesiredfortraining,butthatwasnotfeasiblegiven
thesponsor’sproductdevelopmentschedule.
Duringthethink-aloudtest,theexperimenter,seatedin
thefrontpassengerseat,presentedasheetofpaper,oneper
task,describingthetasktoperformandthedatatouse,and
Experimenter
askedthesubjecttothinkaloudwhiledoingthetask.When
Subject
subjects fell silent for an extended period of time (typically
30s, but sometimes longer), the experimenter prompted
Supercircuits PC502XP camera them. (“What are you looking for? What are you expecting
aimed at the subject’s face
to see? Are you confused?”) Generally, few prompts were
needed. ere were no speci�c rules about which prompt
F 5: Experimenter and a hypothetical subject interacting.
to use when. Although these prompts seem leading, it was
Note:notshownarethePanasonicWJ-420quadsplitter,theSharp
oenapparentfromwhatsubjectssaidandtheiractionswhat
LC10-A3U-B10inLCDmonitor,thePanasonicDMR-EZ47VDVD
thatthesubjectstatewasconsistentwiththeseprompts.For
recorder,theAudioTechnicamicrophone,ortheMackieDX8digital
example,ifasubjectrepeatedlyswitchedbetweenscreensbut
audiomixer.
didnotselectanythingelse,then“Whatareyoulookingfor”
wasanappropriateprompt.
Ifasubjectwasnotmakinganyprogressaerthreeto�ve
minutesonatask(dependingonthetimeremaining),they
weregivenahint.Hintsidenti�edwhattodonext(e.g.,press
this button), without any explanation of why an action was
appropriate.Ifsubjectscontinuedtostruggle,theyweretold
tostopandmoveontothenexttask,astheintentwastoreveal
asmanyproblemsaspossibleinthetimeavailable.
Ascribe(averyfasttypist)satoutsidethesimulatorcab
and attempted to record verbatim what the experimenter
and subject said during the experiment. e only and very
F6:Samplescreengrabfromatypicalsubject.
generalinstructionstothescribeweretorecordeverything
saidandtousethevideoandaudiorecordingsto�llinany
gaps. In part, a verbatim transcription was feasible because
think-aloud method, (3) completed 20 test tasks in a �xed theexperimenterandsubjectwerenottalkingcontinuously,
order while thinking aloud, and (4) completed a 19-page so the scribe was able to catch up during pauses. Anything
surveyrequestedbythesponsor.Practiceinvolvedcounting that the scribe missed (e.g., if the subject spoke quickly)
the number of chairs in the place where they lived, going was �lled in immediately aer each test session (in the 30
roombyroom.Asintended,thesubjectsdidnotsimplylist minutes or so before the next subject) from the audio and
how many chairs were in each room, but said something videorecordings.Havingacompletetranscriptionessentially
aboutthekindofchairspresent,wherethechairswerelocated immediatelyaereachsessionwascompletedshortenedthe
ineachroom,orotherinformation.Iftheydidnotprovide time to reduce the data. Furthermore, aer the fact review
someofthosedetails,thenaquestionwasaskedtoencourage of the audio recordings, collected using a system that was
them. Oen, the process of recalling chairs was a virtual hastily assembled and not optimized for recording quality,
journey (“e front door takes me into the living room. In weresometimeinaudible,especiallywhensubjectsmumbled.
that room Next to that room, around the table ”). e Althoughrequiringascribeinadditiontoanexperimenter
practicewasquickandhelpedsubjectsunderstandwhatwas madetheexperimentmoredifficulttoschedule,givenwhen
meantby“…thinkaloud.” … thisexperimentwasconducted,ascribewasalwaysavailable.
Some 20 tasks were examined (Table 1). ese tasks
were selected because of their importance, frequency of
occurrence,andtoprovidedataonavarietyofentrytypes. 2.4.Subjects. irteenlicenseddriversvolunteeredtoserve
Onlymanualentrywasallowed.Foreaseofadministration as subjects: 6 younger people (ages 19–26, 3 men and
andanalysis,theorderoftaskswas�xed. 3 women) and 7 older people (ages 65–83, 3 men and
Subjectswerenotgivenanydocumentationorinstruction 4 women). ey were recruited via an advertisement on
astohowtheinterfacefunctioned,astheinterfacedesignwas Craigslist.Alloldersubjectswereretired.Fiveoftheyounger
intendedtobeintuitive. subjectswerestudents.Youngersubjectswerethemostlikely
e second author served as the experimenter for the users of the navigation radio, especially of the audio func-
main experiment. He had reviewed the literature on think- tions.Oldersubjectswerethosemostlikelytobechallenged
aloud studies and also served as the experimenter for pilot bytheinterfaceandwouldbethe�rsttoencounterproblems
4 InternationalJournalofVehicularTechnology
T1:Tasklist.
Category # Task Datatouse
1 Enterdestinationviastreetaddressmethod 100North5thAvenue;AnnArbor,MI
2 EnterwaypointviaPOI(PointOfInterest)method NearestMcDonaldsfromcurrentposition
3 EnterdestinationviaPOImethod Nearestgasstationfromcurrentposition
4 Canceltheroute Currentroute
5 EnterdestinationviaPOImethod DetroitMetroAirport
Navigation 6 Changethemapscale Zoomin
7 Enterdestinationviastreetaddressmethod 1600PennsylvaniaAvenue;Washington,DC
8 Enterdestinationviaintersectionmethod US-23andI-94
9 EnterdestinationviaPOImethod CoboHallinDetroit,MI
10 Enterdestinationviaintersectionmethod BroadwaySt.andPlymouthRd.
11 Storeaddress Subject’shomeaddress
CD 12 InsertCDandselecttrack CDprovided,thirdtrack
13 Tuneradio FM91.7
14 Adjustvolume Toacomfortablelevel
FM/AMradio
15 Setpreset FM91.7asthePreset1
16 Adjustvolume Toacomfortablelevel
17 TuneXMradio ElvisStation
Satelliteradio
18 TurnoffXMradio Turnoff
Clock 19 Changeandsettime 11:45pm
iPod 20 ConnectiPodandselectsong “WonderfulTonight”
this study was to reveal. All subjects had corrected visual other factors [25, 26]. Speci�cally, the six subject value
acuity adequate to drive. ey drove a mean of 8,000 miles comes from assuming that each subject has about a one in
peryear,somewhatlessthanistypicalintheUnitedStates. three chance of discovering a problem, that problems are
Other than being a licensed driver, in good health, in independent,andthegoalistodiscover90 oftheproblems.
speci�cagecategories,anativeEnglishspeaker,andexperi- Furthermore, this initial analysis assumes all problems are
encewithXM/Siriusradio,therewerenootherrequirements of a similar severity, and one may have %different goals for
to participate. us, there was no control over experience different level of severity. (See [27] for the most recent of a
withtechnologyinthisexperiment,alimitationnotincluded long series of papers, reports, and now a book chapter on
so subjects could be recruited in the time frame available. samplesize.)
Experiencewithrelevanttechnologywasmixed.Fivesubjects Althoughonecanquibbleonthespeci�csofthecalcula-
owned an iPod, and one owned another brand of MP3 tions,thesurprisetomanynonhumanfactors,nonusability
player.OnlytwoofthesubjectshadvehicleswithXM/Sirius professionals is that most of the problems can be found
radios.FivesubjectsownedGPSsystems:3TomTomsand2 with just a few more than a handful of properly selected
Garmins. subjects. e data from this experiment con�rmed that
Subjectswerepaid 40fortheirtimeiftheycompletedthe conclusion (Figure 7), with most problems being found by
experimentintwohours.Subjectswhotooklonger(someof the �rst few subjects. Testing more subjects would provide
theoldersubjects)wer$epaidanextra 10. better statistical evidence for the frequency of occurrence
e sample, seemingly small, was more than adequate of each problem and would identify more problems, but
for identifying problems, of which 6$4 were identi�ed. “A not many. Most importantly, testing more subjects would
problem was de�ned as a situation where a task took too delay producing a complete report informing the designers
long,subjectsstruggledtomakeprogress,ortheyotherwise ofinterfaceproblemstobecorrected.Inthiscase,boosting
expressed doubt (“I am not sure what button to press”), the con�dence of the sponsor was partly why more than
confusion, irritation (“I would like to shoot the engineer six subjects or so were tested. Further, in these instances,
that designed this”), or other undesired feelings” ([24] when deciding which aspects of an interface to modify, the
page 48). Problems invariably involved deviations from the percentage of subjects who encounter a problem may be
intendedsequenceofstepstocompletethetaskexpeditiously. secondary.Rather,ifjustonesubjectencountersaproblem,
Researchshowsthataeraboutsixsubjectsorso,thenumber andtheproblemseemsreasonable,thenchangestoeliminate
ofnewproblemsfoundwitheachadditionalsubjectissmall, or reduce the impact of that problem should be consid-
with the speci�c number varying the problem severity and ered.
InternationalJournalofVehicularTechnology 5
100 ere were three primary severity categories—critical
90 (“showstopper”),major,andminor(oencosmetic).Acriti-
%) 80 calproblempreventssubjectsfromcompletingatask,suchas
ms ( 7600 not�ndingapowerbuttonoranenterkey.Amajorproblem
e substantiallydelaysthesubjectbutcanbeovercome.Aminor
bl 50
pro 40 problemhasminimalimpactonperformance,butachangeis
d nonethelessdesired,suchasmakingalabeladifferentcolor
n 30
u
Fo 20 or choosing a different font. For this study, task time was
10 usedtodetermineseverity.Tasktimesgreaterthan300s(5
0 minutes)werecritical.Greaterthan30sbutlessthanorequal
1 2 3 4 5 6 7 8 9 10 11 12 13 to300swasmajor.Minorwas30sorless.
Number of subjects In the literature are a number of formal methods to
analyze verbal protocols some of which the authors were
F 7: Cumulative usability problems found as a function of
unawareofatthetimethisexperimentwasconducted(e.g.,
numberofsubjects.�ote:this�guredeterminesthe ofproblems
[28]). However, for the purpose of this applied analysis,
(outof64total)foundutilizingdatafromsubjectsintheorderthey
weretested.So,combiningthedataofsubjects1and2%,38/64=59 given the degree to which the subjects were expressive the
oftheproblemswerefound. experience of the experimenter, and the time available, a
% custom categorization scheme seemed more appropriate.
In brief, problems were categorized as device domain or
3.Results subject domain problems. Device domain problems were
(1) visual or auditory interface related (layout, label, text,
3.�. Data �eduction for Problem �denti�cation. Data reduc- sound, and action time), (2) logic and organization (con-
tion consists of (1) listening to each session to verify each trols, search, system, and information architecture), or (3)
transcription, correcting them as needed, (2) identifying nonusabilitysowareissues(stability,database,andresponse
each problem that users experienced, and (3) identifying time).Subjectproblemsincludeddataknowledge,procedure
the frequency, severity, and persistence of each problem. A knowledge, and preference. In this case, the scheme was to
problem was indicated when a task took too long, subjects aid�oreandesigners,manyofwhowerenot�uentin�nglish,
struggled to make progress, or they otherwise expressed andhadnohumanfactorsbackground.
doubt(“Iamnotsurewhatbuttontopress”),confusion,or Finally,givenfocusonwhatthesponsorneededto�x,the
irritation(“Iwouldliketoshoottheengineerthatdesigned limitedtimeschedule,limitedfunding,noeffortwasmadeto
this”). examine the effect of subject differences (young versus old,
Subjectsindicatedproblemsinseveralways.Indications thosewhohadnavigationsystemsversusthosewhodidnot,
included(1)questions(“Whatisthis?Whereisthebutton? etc.)ontheparticularproblemsencountered.Althoughvery
HowdoIgetthemap?”),(2)statementsofuncertainty(“I’m interesting,theyweresecondaryissues.
not sure if I can have the map when I click on this button.
It does not allow me to save this radio frequency. I am 3.2. How Oen Were Subjects Able to Complete the Tasks?
wonderingwhyit’snotacceptingthis.”),and(3)exclamations Table 2 shows how well subjects did when they were given
with �ller words (“Oh, man ,” “Umm, ”). About 13 hints. One could interpret this data to suggest that the
of the problems for younger subjects were associated with interfacewasrelativelyeasytouse,butthatwasnotthecase.
questions,whereasforolders…ubjects,ques…tionswerelinke%d Many subjects required hints to complete many of the tasks.
toathirdoftheproblems.Incontrast,about81 oftheprob- Had hints not been provided, the success rate would have
lemsforyoungersubjectswereassociatedwithstatementsof beenhalfthevaluesshown,ortypicallylessthan50 ,quite
uncertainty, versus 61 of the problems for o%lder subjects. poor. For perspective, subjects took 2 hours on average to
erewasnodifferenceintheuseof�llerwords(about7 complete these 20 tasks, which is about 6 minutes%/task, a
for both age groups).%Speci�c examples of how particular longtime.Severalofthetasks,suchassettingapresetradio
problemsidenti�edappearlaterinthispaper. % frequency,shouldonlytakeafewsecondstocomplete.
ere were instances during the experiment where the
subjectwassilentforanextendedperiodoftime,wherethere 3.3. How Oen Did Problems Occur and How Severe Were
were no probes from the experimenter, and where it was ey? Table 3 lists the 64 problems, a rather large number,
uncertainfromthetranscriptandvideorecordingwhatthe from the most frequent to the least frequent. About two-
subject was thinking. is oen occurs with novice exper- thirdsofallproblemswereexperiencedbyatleast2subjects.
imenters as they focus on observing what subjects do. One Among those, 16 problems (25 percent of the total) were
solutionwouldbeatimingdevicepromptedtheexperiment encounteredbymorethanhalfofallsubjects.Inthereport
(unobtrusively to the subject) to probe the subject to think summarizing this project [24] the frequency of problems
aloud. wasreportedmanyways.Forthetablethatfollows,theyare
Frequencyisthenumberoftimestheproblemoccurred, reportedatthenumberofsubject(outof13)experiencinga
usuallyacrosssubjects,butsometimeswithinsubjectgroups. problembecausethiswastheformatmostreadilyunderstood
Persistencecanbethenumberoftimesaproblemreoccurred bythesponsoranditsinterfacedesigners.Furthermore,the
withineachsubject. experimentwasdeliberatelydesignedtominimizerepetition
6 InternationalJournalofVehicularTechnology
T2:Successfulcompletionwithhints.
Success
# Task #Notdo
#
1 Setdestinationto100north5thavenue,AnnArbor,MI. 9 69
%
2 FindthenearestMcDonaldsandsetitasawaypoint. 8 62
3 Findthenearestgasstationfromthecurrentposition. 11 85
4 Canceltheroutethatyouhavesetup. 10 77
5 EnterandsetadestinationtothemainDetroitAirport. 12 92
6 Changemapscaletozoominslightly. 10 77
7 Enterandsetadestinationto1600PennsylvaniaAve,WashingtonDC. 10 77
8 SetthedestinationtotheintersectionofUS-23andI-94. 1 8
9 SetthedestinationtoCoboHallinDetroit,MI. 9 100 4
10 SetthedestinationtointersectionofBroadwayStandPlymouthRd,AnnArbor. 9 100 4
11 Enteryourhomeaddressandstoreit. 3 50 7
12 InserttheCDandselectthethirdtrack. 13 100
13 Adjustvolumetoacomfortablelevel. 13 100
14 TuneFMradioto91.7. 13 100
15 Adjustvolumetoacomfortablelevel. 13 100
16 Savethefrequencyas�rstpreset. 6 46
17 TuneXMradiotoElvisstation. 10 77
18 TurnoffXMradio. 12 100 1
19 Changethetimeto11:45pm. 13 100
20 ConnecttheiPodandselectthesong“WonderfulTonight.” 12 92
Note:undertheheadingsuccess,#referstothenumberofsubjectsoutof13whosuccessfullycompletedthetaskwithhints.us,fortask1,100 9/13=
69 .e#NotDoreferstothenumberofsubjectswhowerenotaskedtodouptofourtaskstokeeptheexperimentfromtakingtoolong.us,fortask9,
only9ofthe13subjectsperformedthetask,butall9ofthem(100 )completethetask. ×
%
%
oftasksandtaskelements,andtherebymorewidelyexplore esystemoenfroze(problem10)whiletheexperiment
the interface, which tend to limit repeated encounter with was in progress (for 11 of the 13 subjects, and for some
problems. subjects, multiple times). Given that a prototype was being
e linkage between what was observed and these evaluated, some problems were expected. e work around
problems can best be described by example. Following is the freeze was to unplug the system, plug it back in again,
a description of some of the most frequent and critical andwaitforthesystemtorestart.isprocesstookaminute
problems.Problemswereidenti�edbyacombinationofhow or so to complete and was mildly annoying to subjects and
long it took to complete each task and step (if they were experimenters.Althoughtestingcouldhavebeenconducted
completedatall),whatsubjectsdid,whatsubjectssaid,and when the interface had fewer bugs that froze the interface,
although not described here, their facial expressions. e that testing would have occurred later in design when
ultimateindicationofaproblemwaswhentheysaid,“Igive therewaslesstimeandfewerresourcestocorrectproblems
up.”Quitefrankly,identifyingwhenaproblemhadoccurred identi�ed.
wasfairlyobvious. For task 16, 10 of the 13 subjects could not �gure out
e most frequent problem (9) was that the system did howtosettheradiopresets(pushandholdthesobutton),
notaccept“DC”asastatenamewhensubjectssearchedfor problem42.Whentheyreachedthepresetscreen,theywould
anaddressin Washington,D.C(task1). All subjects except saysomethingsuchas“Whereisthesetbutton?”Oen,they
one(92 ofthesample)triedtotype“DC.”eywouldget would push “autostore,” which reset all the presets. In fact,
to the state �eld and type in “D.” Immediately, the C key onesubjectdidthisthreetimes,exclaiming,“Whydiditdo
wouldg%rayoutbecausethesystemwasexpectingthesubject that, again!” when the desired frequency setting appeared
to type “District.” “Why is the C key gray? I want to type onadifferentbuttonthanitwaspriortopressingautostore.
it.”Incontrasttomoststatenames,theDistrictofColumbia Subjectsdidnotrealizethatthemethodusedtopresetaradio
isinvariablyabbreviatedas“DC,”butthesowareaccepted frequency that works for radios with mechanical buttons
only“DistrictofColumbia.”Allowingtheintelligentspeller (pushandhold),alsoworkedhere.
toacceptbothcompletenamesandtwo-letterabbreviations Some 9 of the 13 subjects had trouble understanding
wouldeliminatethisproblem,andspeedtheentryofother thelabeltochangethekeyboardfromalphabeticmode(the
statenamesaswell. default) to numeric mode (problem 2), a step required to
InternationalJournalofVehicularTechnology 7
T3:Listofproblemsbyfrequencyforall13subjects.
Frequency Problem# Severity Description
12 9 Major Statenamecannotbeabbreviated(DC,WashingtonDC)
11 10 Minor Systemfreeze
10 14 Minor Nowaytoenterhighwayintersectionasdestination
10 42 Major Nointuitivemethodtosaveradiofrequencyaspreset
9 2 Major Difficulttoswitchkeyboardtonumberkeys
CouldnotsearchforanXMchannelbyname,sotheybrowsedthenumericlisting,
9 20 Major
whichwasslow
9 24 Critical Typedbuildingnumberinthestreetname(north/no)
9 35 Major SearchingforaniPodsongbytitlewasverytime-consuming
8 4 Minor Guidancevoicequalitywasinadequate
8 6 Critical Nointuitivemethodtocancelroute/destinationonmapscreen
8 7 Major Buttonsareeasilyconfusedwithdisplays
8 8 Major �xpectedthisinterfacetosupportmultitouch,inparticular2-�ngerzooming
8 17 Minor Correctaddressrejected(wronghousenumberrange)
7 28 Major Didnotrealizewhatthesearchbuttondid(alsousedforenter)
7 29 Major Incompleteandinsufficienttextinformation
7 37 Critical Noalphabeticinputmethodfornumericstreetname(FihAve)
6 3 Minor Negativeresponsetoautosuggestkeyboard(autocompletefunction)
6 13 Major Didnotrealizethereweremultiplepagesfordestinationscreen
6 32 Major Confusingintersectionsearchguidance(“X”,“space”)
6 36 Major Nointuitivemethodtostoretheenteredaddress/homeaddress
Didnotunderstandiconsonthemapwindow(Z,compass,�ag,currentposition,
6 45 Major
scale)
5 23 Major Typedbuildingnumberinthestreetname
5 26 Major DidnotunderstandtheacronymPOI
4 5 Major DidnotunderstandPOIsymbol/functiononthemap
4 16 Minor Searchdisplayedmultipleentriesforthesamedestination(3AnnArbor)
4 22 Major Difficulttoswitchtoalphabetkeys
Nointuitivemethodtosearchforawaypointandadditasawaypointonthemap
4 25 Critical
screen.
3 11 Minor Tooslow/fastsystemresponsetime
3 12 Minor Address/textinformationwasnotlegible
3 27 Major Didnotrecognizescalebuttononthemapscreen
3 30 Major Nowaytobackup(e.g.,mainmodescreen,simulationmode,andlocalPOI)
3 33 Minor NointuitivemethodtobringupCDcontrolaerinsertingCD
3 34 Major DidnotunderstandlabelSAT
3 38 Major DidnotunderstandlabelZagat
3 39 Major Didnotrecognizebackbutton
3 40 Minor UnabletogettoCDmodeaerinsertingCD
3 41 Major DidnotunderstandAutostore
3 44 Major Didnotunderstandiconsonthestatusbar
3 57 Major Nointuitivegraphictoselectthesearchedresultonthelist(city/street)
2 46 Minor Scalewindowdisappearstooquicklyonthescreen
2 48 Major NarrowsearchcoveragebyPOIName(nosupportforMcDonalds)
2 50 Major Didnotrecognizethedeletebuttononkeyboard
2 64 Major DidnotunderstandlabelMapkey
1 1 Minor StatenameishighlightedandshownonSearchbyAddressscreen.
1 15 Minor Confusingsearchresult(AnnArbor/AnnArborTwp)
8 InternationalJournalofVehicularTechnology
T3:Continued.
Frequency Problem# Severity Description
1 18 Minor Misunderstoodseek/trackbuttonlabel
1 19 Minor Didnotnoticevolumelabel
1 21 Major NointuitivedistinctionbetweenRouteandDestkey
1 31 Minor Wrongscreeninstruction(“searchbyPOI”inintersection)
1 43 Minor DidnotunderstandlabelDest
1 47 Minor Selectbuttonlocationwasinconsistent
1 49 Minor Didnotunderstand“Alternative”menu
1 51 Minor MisunderstoodAsian,Korean,andChineseonPOIlist(aslanguage)
1 52 Minor Nowaytocontrolvolumeonthescreen
1 53 Minor Didnotunderstandpresetscan
1 54 Minor MisunderstoodATMandBankonPOIcategorylist
1 55 Minor Wrongunitinformation/temperature
1 56 Major Didnotunderstandplay/stopicon
1 58 Major Didnotunderstandnumbersnexttothesearchedstreetnames
1 59 Major Notabletosetclockinexpectedmanner
1 60 Major Nointuitivelayoutforhousenumberinput
1 61 Minor Didnotunderstandorangelineonthemap
1 62 Minor Noautosavefeatureinenteringcity
1 63 Minor ConfusingcategorizationonPOIlist(gasstation-travel/automotive)
Note:Problem#:e64problemswerenumbered1–64.
completetask1.eydidnotrealizetherewasakeyonthe abletocompleteentryofastreetnamecontainingadirection,
alphabetickeyboardscreentochangemodes,sotheywould evenwithhints.Oentheytriedusingexactlythesameand
search for other screens using the back key, proclaiming stepsmultipletimes,sayingsomethingsuchas,“Ithinkthis
somethinglike“whereisthenumberscreen?”Atothertimes, isthewaytodoit,butImusthavenotdoneitquiteright.”
they could say, “I do not know where it is, so I will try eydidnotrealizethesystemwouldnotacceptthedataas
everything,” and they selected each key on the screen one theyenteredit.
by one to learn what each did. Some subjects who were Subjectsalsostruggledwithstreetnamesthatcontained
methodical in their efforts found the alphabetic keyboard numbers (e.g., 5th street) as only one method of entry was
mode key in this manner. e source of the problem was supported,eventhough subjects maychoose toenterthose
thatthemodekeys/buttonslookedlikeotherbuttonsonthe streetsasnumbersoralphabetically(Fih).Numberedstreets
keyboard, and there was no spacing or graphics to group arequitecommonintheUnitedStates.
them apart. ere were other buttons for which functional Related to this were problems associated with subjects
grouping, indicated by spacing and graphics, would have not realizing what had been set or was a default. is was
helpedaswell. particularly true with setting the state. Keep in mind that
In fact, subjects had numerous problems with so but- many cities are located on rivers, because rivers provide
tons.First,therewasnographicdistinctionbetweenbuttons both water and transportation. However, rivers also serve
and displays, so that when subjects were not sure what to asageographicalboundary,sogoingtoanearbyplacemay
do, they pressed everything, including displays. Providing requirechangingthestate.
buttons with a drop shadow or other unique graphical Problems in search for songs and radio stations were
characteristic as well as auditory feedback (a click sound) common. In part, this was because the interface for each
whenbuttonsareoperated should reduceconfusion. When mode (AM/FM, XM, etc.) was unique. e criteria on
driving, drivers should not be looking at the display. Many which one could search was unique to the mode, and most
interfaces have a beep to con�rm that a switch has been importantly,sowastheorganization.Whatcouldbesavedor
pressed, but that beep is oen the same as the beep for an presetvariedwiththemode,includingwhatsavesorpresets
error,whichconfusesdrivers. were named. As a consequence, subjects needed to browse
Also noteworthy were two problems related to street through pages of screens to �nd an XM radio station or
addressentry.ManyAmericanstreetnameshaveadirection songonastoragedevice,whichwasaverytime-consuming
as part of the name (e.g., North Main) and subjects were process. Manually scrolling through a list of 100 or more
uncertainiftheyshouldenterthestreetnameasNorthMain, itemsandreadingthemto�ndadesireditemshouldnotbe
MainandselectNorth,orabbreviateNorthasNorNO.Only donewhiledriving,especiallywhenthelistsareinanorder
one option was provided, so only 9 of the 13 subjects were thesubjectcannotusetospeedthesearch.
InternationalJournalofVehicularTechnology 9
In summary, from most to least, problems included T 4: Problem numbers listed summarized by frequency and
unclearlabels(20instances,suchasthatforthenumberkey severity.
and the name autostore), problems with search (10, such
Severity
as a lack of consistency in method names and methods
available,especiallyin�ndingsongsand�Mstations),poor Frequency Critical Major Minor
graphics (9, many icons were meaningless), disorganized ( 300s) ( s) ( )
system (9, information such as destination modes being
12 9
split across 2 screens), illegible text (5, mostly text that 𝑡𝑡𝑡 300≥𝑡𝑡𝑡30 30≥𝑡𝑡
11 10
was too small, especially on maps), poor layout (4, such
10 42 14
as inconsistent location of the “ok” and “done” buttons),
otherorganizationalissues,unreliablesoware,anddatabase 9 24 2,20,35
errors (2 each, including missing addresses), and problems 8 6 7,8 4,17
associatedwithunrecognizablesounds,slowsystemresponse 7 37 28,29
(2types),anddisorganizedcontrols(all1each).
6 13,32,36,45 3
5 23,26
4 25 5,22 16
3.4. Persistence. Using persistence to identify problems was
less useful here than has been identi�ed in the literature. 3 27,30,34,38,39,41, 11,12,33,40
44,57
Examples of the most persistent problems included not
understandingtheacronymPOI,notunderstandingiconsin 2 48,50,64 46
themapwindow,systemfreeze,notknowingwhatthesearch 1,15,18,19,
button did, expecting multitouch to be supported, and not 31,43,47,49,
1 21,56,58,59,60
understanding the label Zagat. If anything, the persistence 51,52,53,54,
55,61,62,63
data reinforced the need for better icons and graphics, and
potentiallyeliminatingiconsinsomecases.Asanexample, Note:forthedescriptionscorrespondingtotheproblemnumberslistedhere,
seeTable3.
there were two screens from which subjects could select a
method to enter a destination. Oen, they did not realize
therewasasecondscreen,sotheywerestuck.eiconswere To help designers prioritize what they should do, tables
of no help. Had the icons been removed, leaving only text, were created using pairs of the dimensions of interest (fre-
all of the entry methods would be on one screen and user quency, severity, and persistence). Ideally, designers should
performancewouldlikelyhaveimproved. consider those dimensions, the effort required to �x each
Althoughtherearenumerousnavigationsystemsinuse problem, and the implications of �xing each problem on
today, and many of them use icons, there are no standard otherproblems,aswellasotherfactorsinmakingdecisions
icons for navigation functions in ISO Standard 2575 [29]. aboutwhatto�x.
Althoughitmaynotbepossibletodevelopwell-understood efrequency-severitytable(Table4)containsthemost
iconsformanyofthenavigationfunctionsofinterest,what- usefulofthedimensioncombinations.eproblemslistedin
everisdevelopedcouldbebetterthanthecurrentsituation, theupperleareaofthetable(e.g.,9,42,24,2,20,and35)
whereiconsvaryfromsystemtosystem. arethemostfrequentandsevere,andtherefore,ofthehighest
priority.
3.5.CombinedAnalyses. Whenpresentedwithahugelistof 4.ConclusionsandDiscussion
problems,suchasthoseinTable3,thedesigners’immediate
reactionisoentoignoretheoverwhelminguserfeedback. ere were many problems with this interface, some of
First, there is disbelief that subjects experienced all of the whichwereexpectedearlyindesignwhenthisinterfacewas
problems listed. erefore, two representatives from the examined. Subjects consistently needed hints to complete
sponsorresponsiblefortheinterfacedesignobservedevery tasks,whichwasnotindicativeofanintuitiveinterface.
subject, so they saw that the problems were real. Unfor- One might criticize the sponsor of the research for the
tunately, they were not native English speakers, so for the existence of these problems. However, the more important
�rst few subjects they struggled to understand what was point is that they supported quali�ed experts to examine
occurring. at was overcome by impromptu discussions theirinterface,identifyproblems,andsuggestimprovements.
with them between test sessions or at the end of the day to Keepinmindthatitisnottheresearchers’roletomakethe
explainwhatwasobserved.Alsoprovidedwereafewvideo changes desired, and what is changed represents a tradeoff
outtakes for others not present. In a subsequent project, a between user impact, cost, schedule, and hardware and
secure web camera in the test room was provided so those sowarelimitations.
not present could observe the experiment. In this case, the
13-hourtimedifferencebetweenthetestfacility(AnnArbor, 4.1. Lack of Style Guide. ere were inconsistencies in the
Michigan,USA)andthesponsor’smainengineeringcenter interface,forexample,wherethe“done”or“ok”buttonwas
(Yongin-Shi, Gyunngi-Do, Korea) makes remote viewing located(andhowitwaslabeled).Accordingtothesponsor’s
inconvenient. representatives,therewasnostyleguideorotherspeci�cset
10 InternationalJournalofVehicularTechnology
ofguidelinesgoverningtheinterface,asituationthatgreatly but there were instances where spacing and graphics could
increasesthelikelihoodofproblemsduetoinconsistencyin havebeenutilizedforthispurpose.
theuserinterface.Creatingastyleguide,especiallyonebased
onresearch,isamajortask,butwellworththeeffort.Most 4.7.ButtonsandDisplaysLookedAlike. erewerenocom-
computer manufacturers have style guides to help ensure mongraphicalelementstocontrols(primarilysobuttons)
theirinterfacesareconsistent(e.g.,[30]). and displays (mostly icons), so that when subjects were
lost,theypressedeverything(problem7).Insuchinstances,
4.2.InconsistentMusicInterfaces. esearchmethodsavail- havingdifferentauditoryfeedbackforoperationofabutton
ableandwhatcouldbestoredaspresetsvariedwiththemedia anderroneousoperationwouldhavebeenhelpful.
andarere�ectedinproblems16,20,28,35,andothers.ese Manyoftheseproblemsarenotnew(See[31]).
inconsistencies led to interfaces that were unique to each Beyond this speci�c interface, which does this exper-
media,makinginterfacenavigationdifficult.Admittedly,the iment say about how think-aloud experiments should be
underlying databases have different structures, but a more conducted?
commonformatandmoresimilarsearchfeatureswouldhave
beenbene�cial,sothatsubjectswouldonlyneedtolearnone 4.8. More Experimenter Training Needed. More time was
set of search methods that were consistently named, not a neededtotraintheexperimenterinthethink-aloudmethod,
unique set of methods for each data set. Interestingly, this inparticulartimespentontestingpilotsubjectsandreview-
system (and most others) did not allow for aggregation of ing video recordings of them. In this project, there were
all favored music presets (AM/FM, XM, etc.) on a single two days between when the interface actually worked and
screen. when testing had to begin to deliver results to meet the
sponsor’s production schedule, far too short. A minimum
4.3.DestinationEntryProblems. erewerenumerousissues of two to three weeks is recommended. Training is par-
withdestinationentry,mostduetolimitingthewaysinwhich ticularly important for nonnative speakers of the language
informationwastobeenteredandnotmakingapparentwhat of subjects or those who do not have extensive experience
hadalreadybeenset.eseissuesarere�ectedinproblems in testing human subjects as experimenters. Typically, they
14,16,17,37,andothers. do not prompt subjects enough, or more generally, just
have problems in reading subjects, not knowing when to
4.4.IconsWereNotUnderstood. erewasadesiretoprovide engagethem.isneedwasre�ectedinsilentperiods,where
icons so the interface would be language independent and neitherthesubjectortheexperimenterspoke,andoenthe
usable by a wider user group. at assumes the icons are experimenter just starred at the screen. In other situations,
understandable, which was not true here. Although better when designers without human factors/usability expertise
icons could be developed and included in ISO Standard conductthetesting,excessiveleadingofsubjectsisobserved,
2575, how well they will be understood is uncertain. at typicallyinvolvingtellingsubjectshowtocompleteatask.
suggests for some parts of the interface, icons may not be A list of probe questions and criteria for when those
provided.Inthecaseofselectingadestinationentrymethod, questions should be asked would be a useful addition to
all of the methods will �t on one screen instead of being thetrainingmaterials.Beingrepeatedlyasked“whatareyou
distributedacrosstwoscreens,makingiteasierforusersto thinking”isannoying.Formalrulesaboutwhentointervene
�nd the desired method. In other cases (e.g., maps), icons and what to do (just press this button, but not saying why)
must be provided, as there is insufficient space for text (let canbehelpful.
aloneiconsplustext).However,inthisinstance,mosticons Another idea is a device that would look for periods of
werenotunderstood(problems44,45,64,etc.).Infact,ina silence and subject inaction. When those periods occurred
verylengthyexaminationoftheiconsusedinthisinterface, forsometime,thedevicewouldvibratesomethingonwhich
conductedaeralltaskswerecompleted,onaverageonly2of the experimenter was sitting as a reminder to ask a probe
the13subjectswereabletocorrectlyidentifywhatthevarious question.
iconsmeantwhenshownincontext.Easytounderstandmap
iconsneedtobedeveloped. 4.9. Real-Time Session Recording Helped. Secretaries or stu-
dentswhowerefasttypistssatintheroomwiththesubject
4.5.LabelsWereNotUnderstood. isincludedPOI(prob- andtheexperimenterandservedasthescribe,creatingthe
lem 5), SAT (problem 34), Zagat (problem 38), and others. session transcripts. Immediately aer the session, when the
Eachofthelabelsusedshouldbeconsideredandalternatives session was fresh in their mind, the scribe checked their
proposed. is needs to be done in conjunction with the transcriptagainsttheaudioandvideorecording.Forthisto
efforttodevelopnewiconsastheyareanalternativetotext occur,morethanafewminutesisrequiredbetweensubjects.
labels. Nonetheless, generating transcripts in real time rather than
aer the fact from a video recording reduced the time to
4.6. Lack of Functional Grouping. ere were several provide the results to the sponsor, which was important
instances where information on screens was not grouped where a real evolving product with a rigid development
by function, increasing the time for users to �nd particular schedulewasconcerned.
information(andincreasingerrorsaswell).ebestexample ere was no evidence that the presence of a scribe
ofthisisproblem2.Admittedly,spaceisextremelylimited, was disruptive, which was a concern. For example, subjects