ReseaRch MethoD 87Think-aloudProtocol Think-aloud protocol is a method that requires participants to verbalize what they are doing and thinking as they complete a task, revealing aspects of an interface that delight, confuse, and frustrate. 1 Think-aloudprotocolisamongthemostcommonevaluativemethodsintheusabilitycommunity. Theprotocolisstraightforward--itaskspeopletoarticulatewhattheyarethinking,doing,orfeeling astheycompleteasetoftasksthatalignwiththeirrealisticday-to-daygoals.Asacornerstone methodoftheusabilityprofession,itaffordsresearcherswithatried-and-trueapproachnotonly toseetheprocessoftaskcompletionunfold,butalsotoidentifytheaspectsofadigitalorphysical productthatdelight,confuse,andfrustratepeoplesothattheycanbecorrectedorimproved.There aretwocommonexperimentalproceduresforthethink-aloudprotocol: Concurrent Think-aloudisthemostcommonwaytoconductthemethod.Theparticipantworks throughtaskswhilearticulatingwhatheorsheisdoing,thinking,andfeeling.Dependingona myriadoffactorsrangingfromtheparticipant'spersonalitytotaskcomplexity,evaluatorsmayhave torepeatedlyremindparticipantstoverbalizewhattheyarethinkingastheyworkthroughatask. Thefocusofthetestshouldbeonwhatishappening,asopposedtowhy;peoplearereasonably abletospeakaboutandcompleteataskatthesametimewithoutimpactingtheoutcomeofatask. 2 Retrospective Think-aloudbeginsbyaskingparticipantstocompleteataskinsilence(whiletheir activityisrecordedwithvideoand/orascreen-capturedevice).Upontaskcompletion,participants 1.Thethink-aloudprotocolwasadaptedfor useintheHumanComputerInteraction communityanddocumentedbyClayton Lewis,anIBMresearcherinTask-Centered User Interface Design: A Practical Introduction.Thepurposeoftheprotocolis tohelpresearchersunderstandwhataspects oftheinterfacepeopleareprocessingas theyattempttocompleteaspecifictask. Alsosee: Newell,Albert,andHerbertA.Simon.Human Problem Solving.EnglewoodCliffs,N.J.: PrenticeHall,1972. 2.Ericsson,Anders,andHerbertA.Simon. Protocol Analysis: Verbal Reports as Data, Reviseded.Cambridge,MA:MITPress,1993. 3.Guan,Zhiwei,ShirleyLee,Elisabeth