Unit 2

Two main cells in the LGN 

1. Magnocellular (layers 1 and 2) M cells 

• fast , large receptive field, input from periphery. 

2. Parvocellular (layers 3-6) just P type ganglons

• Smaller receptive fields, slow, input from middle.

Where does the ventral stream start and where does it project?

primary visual cortex (V1) and projects to the bottom (ventral) surface of the temporal lobe.

IT cortex

neurons that respond to complex objects (bottom of ventral surface in temporal lobe)

Prosoprognosia

facial blindness

Marry potter scene theory

the gist in under 250 and can go low as 50

Alternate paradigm

present image briefly and see what people can repor

Visual persistence

 perception of visual stimulus for 250 ms after saw it in our mind. (if i presented photo for 50, overall we’d perceive it for 300)

To account for visual perisstsance we can use masking

Image shown and then tv static shown immediately after to mask.

Lee Fei-Fei theory

masking

Whta allos us to rapidly percieve teh gist of a scene?

its global features and figure ground principles

Global image features

1. Degree of naturalness

2. Degree of openness

3. Degree of roughness

4. Degree of expansion

5. Colour

Likelihood principle

 objects are perceived based on what is most lieklt to cause thepattern. 

Theory of unconscious interference

we are inferring object identification due to to the information we have at the moment.

Bayesian inference:

our estimation of the probability of an outcome is determined by two things 1. Prior beliefs coming into the situation 2. The likelihood of the outcome

priors x likelikihhod

Predictive coding

 the brain using past experiences to predict what we will perceive. When something unexpected happens we perceive a prediction error. 

Binocular rivalry

when each eye receives a different image (e.g., a face in one eye and a building in the other). The brain cannot merge them into a single image, so perception alternates between the two images over time.

Thatcher effect

we process faces holistically when they are upright. When a face is inverted, we struggle to notice distortions (e.g., flipped eyes and mouth), revealing our reliance on configural processing.

• people with propospragnosia process this better because they dont relyon holistic face processing.