Lecture 3 - Perception, Knowledge and Action Flashcards
What is perception?
How the brain makes sense of the patterns of reflected light that we experience.
What is size constancy?
The fact that as we move away, the size of a projection on the retina decreases, but we still know it’s the same size.
What is shape constancy?
The idea that as we move around an object or it rotates, we see different patterns of light yet recognise that the object is the same.
What is binocular parallax?
The discrepancy of info received by each eye, used to determine distance as closer objects have greater parallax.
How do we perceive depth?
- Binocular parallax (stereopsis)
- Monocular cues: size/visual angles, occlusion, texture gradient, lighting/shading, motion parallax.
What is motion parallax?
The movement of one object relative to another - closer objects shift faster.
What did William James believe about the development of perception?
That we learn to perceive from learning and experience.
What did Gibson and Walk (1960) do?
The visual cliff experiment - 8 months old wouldn’t crawl over deep side. Not the result of binocular parallax as babies with eye-patches behave in the same way.
The visual cliff experiment findings suggest that babies perceive depth through motion parallax, but is this ability from birth?
Babies learn to use motion parallax when they start to crawl in order to avoid collision, as shown by the visual cliff experiment done on 7mos who could/n’t crawl or use a wheeled walker. Campos et al (1992)
What did Bower (1965) do?
Conditioned 3mos to like a 30cm cube (as indicated by increased dummy sucking) and presented various cubes at different distances. Found that they recognised the cube at greater distances, but also a lager cube at a larger distance with the same retinal image size. They therefore have some understanding of depth perception.
What did Slater et al. (1990) do?
Used the habituation paradigm to get 2 day old babies to show decreased interest in a cube with a distinctive pattern at a fixed distance. Then showed a different sized cube at various distances, they showed interest = recognised it was new. Suggests that size constancy and depth perception is innate.
What is the value of depth perception and size constancy?
Can recognise and have a defensive reaction towards objects heading for you.
What did Bower et al (1970) find?
That 2 week olds had a defensive reaction when objects were projected towards their faces.
What did Ball and Tronick (1971) find?
That 2 week olds had a defensive reaction for rapidly expanding patterns (train image) on a screen.
Also that other expanding patterns not on a collision course did not elicit a defensive reaction.
What did Kelman and Spelke (1983) do?
Showed 3mos a white bar moving over a black bar, then in test phase they preferred a broken bar indication that they knew the first bar was occluded and didn’t perceive it as a novel object.
