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SUMMARY:Crowding and the disruptive effect of clutter throughout the visua
 l system - Dr John Greenwood\, Department of Experimental Psychology\, UCL
DTSTART:20171121T130000Z
DTEND:20171121T140000Z
UID:TALK74691@talks.cam.ac.uk
CONTACT:John Mollon
DESCRIPTION:Our ability to recognise objects is impaired in cluttered scen
 es\, even for objects that are clearly visible in isolation. This process\
 , known as crowding\, is most evident in peripheral vision where it disrup
 ts the recognition of a range of visual stimuli (including orientation\, m
 otion\, colour\, and faces) across large spatial regions. Crowding also be
 comes elevated in foveal/central vision in visual disorders ranging from a
 mblyopia to dyslexia. \n\nIs there a common mechanism for these diverse ef
 fects? I will argue that ‘pooling’ models\, which depict crowding as a
 n unwanted combination of target and flanker elements\, can indeed provide
  this. In peripheral vision\, crowded errors are not random\, but rather r
 eflect the combined appearance of the target object and surrounding flanke
 rs. We observe a similar pattern of errors in the foveal crowding that aff
 ects children with amblyopia\, which pooling models simulate closely. Simi
 larly\, although it has been argued that crowding disrupts face recognitio
 n in a manner unlike that of simpler objects\, we find that simple pooling
  processes provide a more parsimonious account. Finally\, I will demonstra
 te that crowding can independently disrupt judgements of colour and motion
  for the same target object\, suggesting the existence of multiple instanc
 es of crowding. Although this finding challenges ‘higher level’ crowdi
 ng approaches\, it is easily explained by pooling models. 
LOCATION:Kenneth Craik Room\, Craik-Marshall Building\, Downing Site
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