ABSTRACT
Whendrivingthroughtheenvirorunent,visualinformationseenbythedriverchanges dynamically.Thisopticalflowcontainsspecificinformation,whichisusedbythe drivertosteertheirvehicle.Oneimportantquestioniswhetherattentionalshiftswithin anopticalflowfieldareinfluencedbythelocationofthefocusofexpansion.Therefore thefocusofexpansionwasvariedinspatialdepthforthisstudy.Theopticalflowwas generatedonatwo-dimensionaldisplaybymovingandsize-changingdots.Withinthis dynamicscenerycoloureddotsemergedtowhichsubjectshadtorespond.Reaction timeswererecorded.Tocontrolforeffectsofeccentricity,thefieldwherethedots randomlyappearedwasdividedintotwosectionsrangingfrom0to15°andfrom15to 30°.Theresultsshowedthatattentionalshiftstoemergingdotscanbeperformedmuch fasterwhenthefocusofexpansionislocatedatthebackthanwhenlocatedatthefront. Thedifferentlevelsofeccentricityhadonlyaminorinfluenceonreactiontimes.The resultsareattributedtoattentional-capturingmechanismsoriginatedbydifferent velocitygradients.Theimplicationsoftheseresultsfordrivingbehaviourarediscussed.
Thedistributionofattentionwithinthevisualfieldplaysanimportantroleforsafe drivingbehaviour.Awidevarietyofsourceshasestablishedalinkbetweenattention andtrafficaccidents.ForexampleHendricks,FellandFreedman(1999)foundina studyof723crashesthat37.8percentoftheaccidentswereduetodriverinattentionor perceptualerrors.InanearlierinvestigationbyTreat,Tumbas,McDonald,Shinar, Hume,Mayer,StansiferandCastellan(1979),2,258trafficaccidentswereevaluated andtheauthorsconcludedthatimproperlookoutandinattentionwerethetwoleading causesoftrafficaccidents.
