Theories of Perception - Recognizing Patterns and Objects

Gestalt Approaches

Bottom-Up Processes

Top-Down Processes

Direct Perception (Gibson):

  • denies the constructivist approach to perception (we construct a mental representation)
  • objects and their affordances (acts/behaviours permitted by objects/places/events) are directly perceived

Figure-Ground Organization: segregation of the whole display into objects and the background (e.g. baby and tree picture)
Subjective Contours: simplified interpretation of a complex image (e.g. triangles overlapping)

Principles of Perceptural Organization:
1) Proximity - we group things that are nearer to each other
2) Similarity - we group things that are more similar
3) Good Continuation - we group objects whose contours form a continuous line
4) Closure - we fill in the gaps to create whole figures
5) Common Fate - we group together objects that move together

Law of Prägnanz: general law that we tend to select the simplest interpretation of a display

Template Matching: we compare incoming information to templates we have stored and look for a match

Problems...

  • we have to have stored an impossible number of templates
  • doesn't explain how we are capable of recognizing new things
  • we recognize objects as more or less the same thing even if the patterns differ greatly

Featural Analysis: recognition of an objects relies on the recognition of its features

Recognition by Components (Biederman):

  • we divide the whole into geons (primitive components) and how they are arranged

Pandemonium Model (Selfridge)
???

Problems...

  • no good definitions of what can/cannot be a feature
  • we describe patterns that have no features
  • the same pattern may be described many ways

Prototype Matching: we match incoming information to idealized representation of some class of objects/events (ie.prototype)

Posner - demonstrated that we create representations of similar items when presented with new patterns (dots)
Cabeza - participants could recognize prototypic faces before less prototypical faces

Structural Theories: extension of feature theories that emphasizes relationship between features (cup test)

Marr's Theory: we visually perceive surroundings by constructing 3 mental representation sketches...
1) Primal - depicts brightness and geometric shape
2) 2.5-D - cues such as shading, edges, texture brings info about surface and depth
3) 3-D - info from previous experience or expectation bring recognition of the object and meaning (top-down) #

Perceptual Learning: perception changes with practice

  • perceptually practiced individuals learn what aspects of the stimulus to attend to and can better distinguish between different kinds of stimuli
  • therefore experience appears to enhance the perception of this familiar information

Word Superiority Effect:

Reicher - participants could more accurately identify letters presented in the context of words than presented alone

Missing Letter Effect - we miss f's in words like 'of' (and other function words vs. content words)

Problem:

  • proposals are not well defined and fail to explain perception fully