Chapter 5: Form Perception

Week 6

bottom up processing

physical stimuli influence how we perceive them

ex. eyes detect a reflected long wavelength and we see it as red

top down processing

existing knowledge of objects influences how we perceive them

ex. perceive a rose because we know roses are red and have this specific shape

recognition

ability to match a presented item with an item in memory

representation

storage and/or reconstruction of information in memory when the information isn’t actively being used

perceptual organisation

objects in our environment are grouped so we can identify multiple objects in complex scenes

• allows us to separate similarly shaped objects like books vs bricks

grouping

elements are brought together in common unit

segregation

distinguishing 2 objects as distinct

figure-ground organisation

divide world in 2 parts: foreground (object of interest) and background

law of good continuation

law of proximity

law of similarity

law of symmetry

law of common fate

edge completion (closure)

creates illusory contours

geons

basic units of objects

simple shapes like pyramids and cylinders

recognition by component theory

object recognition occurs by representing each object as a combination of basic units (geons) that make up an object

viewpoint invariance

perception of an object doesn’t change when we look at it from different angles

V4

area of brain concerned with colour vision and shape perception

inferotemporal area

area of the temporal lobe involved in object perception

• gets input from v4

fusiform face area

in inferotemporal area

recognises familiar faces

occipital face area

recognises faces as distinct from other objects

Parahippocampal place area PPA

inferotemporal cortex

scene recognition

topographic agnosia

can’t recognise spatial landscapes

damage to parahippocampal place area

extrastriate body area

inferotemporal cortex

activated when its cells view bodies or body parts but not faces

dull target cost

as the # of objects searched for increases, the likelihood of detecting one of those objects decreases

→ we stop looking once we’ve found the first

issue for cancer readings