?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Optic+flow+based+perception+of+two-dimensional+trajectories+and+the+effects+of+a+single+landmark.&rft.creator=Bertin%2C+R.J.V.&rft.creator=Isra%C3%ABl%2C+I.&rft.subject=Behavioral+Neuroscience&rft.subject=Neuropsychology&rft.subject=Psychophysics&rft.description=It+is+well+established+that+human+observers+can+detect+their+heading+direction+on+a+very+short+time+scale+on+the+basis+of+optic+flow+(500ms%3B+Hooge+et+al.%2C+2000).+Can+they+also+integrate+these+perceptions+over+time+to+reconstruct+a+2D+trajectory+simulated+by+the+optic+flow+stimulus%3F+We+investigated+the+visual+perception+and+reconstruction+of+passively+travelled+two-dimensional+trajectories+from+optic+flow+with+and+without+a+single+landmark.+Stimuli+in+which+translation+and+yaw+are+unyoked+can+give+rise+to+illusory+percepts%3B+using+a+structured+visual+environment+instead+of+only+dots+can+improve+perception+of+these+stimuli.+Does+the+additional+visual+and%2For+extra-retinal+information+provided+by+a+single+landmark+have+a+similar%2C+beneficial+effect%3F+Here%2C+seated%2C+stationary+subjects+wore+a+head-mounted+display+showing+optic+flow+stimuli+that+simulated+various+manoeuvres%3A+linear+or+curvilinear+2D+trajectories+over+a+horizontal+ground+plane.+The+simulated+orientation+was+either+fixed+in+space%2C+fixed+relative+to+the+path%2C+or+changed+relative+to+both.+Afterwards%2C+subjects+reproduced+the+perceived+manoeuvre+with+a+model+vehicle%2C+of+which+we+recorded+position+and+orientation.+Yaw+was+perceived+correctly.++Perception+of+the+travelled+path+was+less+accurate%2C+but+still+good+when+the+simulated+orientation+was+fixed+in+space+or+relative+to+the+trajectory.+When+the+amount+of+yaw+was+not+equal+to+the+rotation+of+the+path%2C+or+in+the+opposite+direction%2C+subjects+still+perceived+orientation+as+fixed+relative+to+the+trajectory.+This+caused+trajectory+misperception+because+yaw+was+wrongly+attributed+to+a+rotation+of+the+path.+A+single+landmark+could+improve+perception.&rft.date=2001&rft.type=Preprint&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Fcogprints.org%2F2121%2F3%2Fpdfprevw1084.pdf&rft.identifier=++Bertin%2C+R.J.V.+and+Isra%C3%ABl%2C+I.++(2001)+Optic+flow+based+perception+of+two-dimensional+trajectories+and+the+effects+of+a+single+landmark.++%5BPreprint%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F2121%2F