perception

• Bottom Up/ Data-driven processes


  Refers to how the information in the stimulus affects perception
• Bottom Up

  Observer akes small amounts of info from the environment and combines it to form a precept
• Bottom Up processes


  Operate reflexively and passively-occurs even when not trying to identify things
• Three major classes of Bottom Up processes

  • Template Matching
  • Feature Analysis
  • Prototype Matching
• Template Matching


  • Perception depends on a physical match between stimulus and stored representation in memory (like a barcode)
  • Proper identification requires an exact match: unless we have stored a template for it, it is impossible to recreate something
  • Not good for capturing flexibility
• Feature Analysis


  • Objects are recognized by recognizing their component parts and the way in which they are combined
  • Selfridge's Pandemonium model: Image demons, nd
  • More flexible: stores features which could be common to many objects, reducing number of templates stored
• Prototype Matching


  • Requires stimulus be matched to a stored representation
  • Match has to be best fit not exact
• Top Down/ Conceptionally driven processes


  Uses background knowledge to influence perception
• Visual Agnosia


  Disruptions in Perception
• Apperceptive Agnosia


  • Have a difficult time maintaining basic representations in memory
  • Won't really be able to distinguish or match objects, can't identify objects if too many contours are missing or if in unusual viewpoint
• Associative Agnosia


  • Can match and copy images but do so slowly and won't be able to identify the images that they just copied
  • Can see the object and know what it is but they would have to be tested in a different way to identify it
• Example of Associative Agnosia


  • Place a coffee cup in front of someone: they cannot tell you what it is, but if they get thirsty they will pick it up and drink it without having to be told what it is
• Prosopagnosia


  • Face blindness
  • Can see details of face but cannot recognize a face as a whole unit
  • Cannot even recognize loved ones or in extreme cases themselves in the mirror
• Galvanic Skin Response (GSR) will show different responses when these people are shown images of loved ones vs strangers
• Prosopagnosia patients display implicit face recognition abilities
• Capgras Syndrome


  • Have overt facial recognition but impaired implicit face recognition
  • Can look at a picture and tell you who it looks like but will claim they are an imposter and will not show any GSR response
  • Thought to be a deficit in reasoning