2. Sensation and perception Flashcards
(19 cards)
What is the definition of sensation?
The detection of simple properties e.g. brightness, colour, loudness
What is the definition of perception?
The [interpretation] of sensory signals e.g. size, movement, identification of location
What are the 2 types of eye receptors called?
Rods and cones
What photosensitive pigment to rods and cones contain?
rhodopsin
Which receptor functions at low light and which at high light intensity?
Rods = low light
Cones = bright light
Which receptor is colour tuned and what does this mean?
Cones are also colour tuned = Each cone is sensitive to either red, green or blue (different rhodopsins).
The retina is made of rods and cones, roughly how many of each are in your retina?
120 million rods
7 million cones
What is the optic nerve formed of?
Formed of axons from 1 million ganglion cells
What is the role of horizontal and amacrine cells?
They are inter-neurones that combine and contrast signals from adjacent photoreceptors
What is the role of ganglion cells in the eye?
They generate action potentials and form the optic nerve
What is the technique of single cell recording and who did it?
Hubel and Wiesel
Insertion of a microelectrode to observe the physical response of a single neurone
Where does input feed into after the retina?
Input feeds into the visual cortex which is hierarchically organised. Starting with V1 (visual cortex 1).
The visual cortex is formed of layers of neurones which process different aspects, what does V1 process?
Lines and edges
For perception, what computational processes does your brain go through ?
Segmentation - what’s part of one object vs another.
Recognition - “That’s a cat”
Building a 3D image
What are Gestalt’s principles of grouping?
Rules your brain uses to group and organise elements. These rules are automatic and innate (we don’t think about it).
Grouped by:
Similarity
Proximity
Good figure
connectedness
What does The Necker cube demonstrate?
That we automatically construct a 3D world from a 2D image - as we can’t tell which plane is the front
What is the “Visual cliff” and who was it done by?
Gibson and Walk
It was used to test whether children or animals can interpret depth cues (will they crawl over the glass cover)- suggests depth perception is innate
What is meant by the concept of perceptual constancy?
Images aren’t always clear so your brain fills in gaps based on past experiences ect:
- Your brain assumes that objects don’t suddenly change shape, size, or colour
- It automatically compensates for things like distance & angle
