DP4

• visual illusion - is a consistent perceptual error in terpreting the features of an external stimulus
• visual illusions provide us with cues that mislead our perception. as a result, a mismatch between our perception and the reality of the actual stimulus occurs
• ames room - A trapezoidal room with slanted walls and inclined ceiling and floor appears square when viewed through a peephole, due to distorted proportions that mislead the viewer about depth and distance.
• ames room - this illusion makes the two back corners seem equidistant from the viewer, even though the rear-left corner is actually farther away than the rear-right corner.
• ames room explanation

  • rooms distortion - both people appear to be equal in distance from viewer
  • People cast different sized images on the observers retina
  • applying size constancy in the usual way to an extremetly unusual situation
  • misapply size constancy, maintain shape constancy
• muller-lyer is a geometical visual illusion where two parallel lines of equal length appear different in size because of the different figures at the ends of each line
• the mulley lyer illusion occurs because the brain interprets the lines based on depth cues and perspectives, assuming one line is further away, altering its perceived length
• visual agnosia - loss of visual knowledge
• causes of visual agnosia:

  • neurological disoorders
  • trauma - head injury
  • environmental events
• visual agnosia

  • suddenly - head injury, stroke
  • gradually - dementia, brain cancer
• characteristics of visual agnosia

  • being unable to recognise faces but able to recognise other objects
  • seeing multiple objects but only recognising one object at a time
  • being unable to name or describe familiar objects when looking at them
• apperceptive visual agnosia - unable to recognise visual stimuli e.g. shapes, and forms of an object despite having no visual deficits
• apperceptive visual agnosia

  • damage to right hemispheres occipital lobe
  • can see object
  • knows what an object is
  • cannot draw object
• associative visual agnosia - unable to recall information associated with an object e.g. name, what used for
• associative visual agnosia

  • damage to both hemispheres at occipitotemporal border
  • cant name, explain object - cant access information from brain areas involved in visual memory
  • can draw object
  • cant distinguish between objects that are real and not real
  • prosopagnosia