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Time-to-passage estimation on periphery : better for biological motion?

Abstract

In  previous  studies,  complex  motion  stimuli  were  judged  as  passing  sooner  than  rigid stimuli  but  reflected  more  uncertainty  in  the  judgments  as  revealed  by  precision  loss  and  longer reaction  times.  It  is  known  that  biological  motion  can  be  perceived  in  the  periphery .  In  the everyday  life  people  are  required  to  interact  with  or  to  estimate  motion  variables  of  other  agents located  on  the  periphery ,  at  different  locations  of  the  visual  field.  In  this  study ,  stimuli  were presented  in  different  peripheral  location  (16°,  32°  and  48°).  In  a  time-­to-­passage  (TTP)  task  rigid (RM),  biological  (BM)  and  scrambled  (SM)  motion  conditions  were  compared.  Seven  simulated velocities  were  combined  with  seven  starting  distances,  resulting  in  49  levels  of  TTP:  24 conditions  that  arrived  before  1s  and  24  that  arriving  after  1s.  Subjects  had  to  decide  whether the  point-‐‑light  walker  (PLW)  passed  the  eye  plane  before  or  after  a  reference  time  (1s)  signaled by  a  tone.  Subjects  could  judge  time  to  passage  of  PLW  peripherally  to  an  eccentricity  of  at  least 48o.  Judgments  for  complex  motion  patterns  (BM  and  SM)  showed  an  anticipation  of  the passage  combined  with  a  loss  of  precision  when  compared  with  RM,  at  eccentricity  16o.  The effect  of  eccentricity  on  precision  was  revealed  by  the  increase  of  SD  along  eccentricities  for SM.  The  TTP  judgment  seemed  to  become  less  precise  as  the  stimuli  were  displaced  farther along  the  peripheral  field.  For  BM,  an  improvement  on  precision  was  verified  at  eccentricity  32o, and  a  subsequent  deterioration  just  at  eccentricity  48o.  The  anticipation  of  the  passage  for  BM was  no  longer  found  on  periphery ,  while  the  differences  on  the  precision  between  BM  and  RM vanished.Fundação para a Ciência e a Tecnologia (FCT

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