Perception II Flashcards
How do we perceptually organise our environment based on a 2d retinal image?
- “Rules” - figure-ground discrimination, perceptual grouping (Gestalt principles)
- depth perception
- perceptual constancy
figure-ground discrimination?
ability to separate the elements of a visual image on the basis of contrast (e.g., light, dark), to perceive an object (figure) against a background (ground)
- figure more memorable and detailed
- figure is meaningful part, “thinglike”
- background can help understand figure, ie. inkspill image, help object identification
- in order to be able to do this we need to be able to separate environmental objects from one another; via object perception/ grouping
stages of object perception?
- local features (Ganzfield)
- shape representation
- object representation
agnosia meaning?
rare disorder characterized by an inability to recognize and identify objects or persons.
agnosia stages?
stage 1 - bindness in part visual field
stage 2 - apperceptive, inability recognise shapes
stage 3 - associative, inability assign memory to stimulus
Gestalt prinicples - general define?
- Gestalt principles used to fill in gaps when can’t see whole image
- about grouping of objects into meaningful figures
- increase perceptual speed
- allow figure-ground discrimination
- allow object recognition
What are the gestalt principles?
- Proximity - closer together more likely to group
- Similarity - more similar more likely to group (size shape color)
- Good continuation - more able to create continuous form thus more likely to group
- Closure - fill in gaps to complete objects
- Common fate - more move in same direction and same speed, more likely
- Synchrony - group when occur at same time
- Common region - group when located in shared boundary
- Connectedness - group elements that are connected by other elements
- Texture - share a pattern or texture more likely to group
Praganz rule?
organisation of visual array into objects will be as good as conditions allow
t/f: gestalt principles are heuristics (rules of thumb)
that guide our organisation of the perceptual
world – group visual scene into objects
t
what is cue theory?
we learn to associate certain cues with depth - after learning, it becomes automatic
3 types of cue in cue theory?
oculomotor
binocular
monocular
state all monocular cues?
• Size of image (familiar size) - ball not growing because I know a tennis ball is of a certain size (backup)
• Occlusion/Interposition - close object blocks distant object, we make a probabilistic judgement
• Linear perspective - outlines of buildings etc. converge the more distant the object
• Height in visual plane - distant objects higher up
• Clarity/brightness - distant object more hazy, less clear
• Light and shadow - object casts shadow
• Texture gradient - object texture less clear further away
• Atmospheric perspective - less contrast between an object and the background the greater the distance
• Motion parallax - moving objects seem faster the closer they are to us
t/f: baby may recognise face mother within few hours of birth
t
t/f: 6 month old baby equalling good at recognising chimp faces as human, until 9 months old when it becomes favourable to view humans
t
prosopagnosia?
inability to perceive or recognise faces - specific damage to brain
