W3_lec1 Flashcards
Describe the following
a) sensation
b) perception
a) sensory receptors transduce stim –> neural impulses
b) interpret sensory inputs –> meaningful subjective percept
Visual perception is contralaterally organized. What does this mean?
this means that stim on the left side is perceived on the right and visa versa
The primary visual cortex receives the bulk of the visual input. What brain region also receives visual inputs?
the thalamus
Describe Psychophysics. Who was associated w/ this type of study?
a) the study of how subjective perception is related to the physical properties of environmental stim
b) Gustav Fechner
What was the results of Gustav Fechner’s idea of Psychophysics?
He found that stim intensity needed to perceive a change in intensity is proportional to the original stim intensity. (need to feel the original stim intensity b/f you can detect a change in intensity and the larger that difference the easier it is to perceive)
What are the 2 basic elements of Vision?
- Contrast = difference in lighting b/w elements that are beside each other
- Orientation = the direction of info contained in an image
Describe Spatial Frequency. Does this relate to contrast or orientation?
a) the amount of detail in an image
b) contrast = the variation of contrast in an image
T or F - we perceive all spatial frequencies equally well
F - the optics of the eye limits our contrast sensitivity to about 60 cycles/deg of visual angle
Based on the contrast sensitivity fxn what is the maximal sensitivity? What about for humans?
a) 5 to 8 cycles/degrees of visual angle
b) 60 cycles/deg of visual angle
Describe Binocular disparity. What is its purpose?
a) each eye receives different info from a single stim
b) used as a means of distance cues for where objects are in space
How is colour perceived? How may this vary for white or black objects?
a) depends on the wave length of light that is reflected by that object (all other colours are absorbed)
b) white = all wave lengths are reflected
c) black = all wave lengths are absorbed
What part of the retina is sensitive to wavelengths of light? Where are they located w/in the retina?
a) photoreceptors = cones
b) in the fovea
Describe the following wrt context and visual processing
a) data-driven
b) concept-driven
a) knowledge –> object recognition –> simple visual features
b) simple visual features –> object recognition –> knowledge
T or F - emotions enhance contrast sensitivity
T - fear makes images more clear
What is the significance of colour constancy?
the difference in background illumination from objects can indicate their location in relation to you but can also trick the brain
How is our interpretation of sensory input shaped?
through prior knowledge
Describe the jumbled word effect
As long as the first and last letters are in the correct order. Even if the middle is messed up. This is b/c our brain doesn’t read every letter by itself but reads the whole word instead
Describe the 5 Gestalt principles of perceptual organization
- Similarity = we tend to gr items that are similar together
- proximity = we tend to gr items that are close in proximity together
- good continuation = we tend to perceive items as a continuation over two different segments
- closure = we tend to fill in incomplete figures
- Simplicity = we tend to interpret an item in the simplest way possible
Describe Denotivity
the idea that features that are familiar and are meaningful tend to be perceived as the foreground
looking at this image what does the following mean?
a) top to bottom/bottom-up
b) bottom to top/top-down
a) data-driven - extracting features around us and put them in our knowledge (gaining info from around us)
b) concept-driven - perceiving info around us based on out prior knowledge of that info
There was an experiment that linked emotion w/ contrast sensitivity. What did they find? What could explain these results? How is this an example of the top-down/concept-driven idea?
a) They found when looking at a dot and trying to decided on which side of the dot there were lines it was easier (despite the low contrast) to see them when shown a fearful face vs a neutral face.
b) the fear emotion tends to increase the sensitivity of the visual system
c) this INC in sensitivity in the visual sys will only occur if one understands what a fearful expression looks like based on prev knowledge/exp
how does this image display show colour constancy of the brain is not always accurate? What is the brain trying to do? What is another example of the brain being tricked by colour consistency?
a) We perceive square A to be darker than square B however, they are the same shade.
b) The brain is trying to compensate for the colour b/c of the presence of the shadow and b/c it wants to see the completeness of a checkered board
c) the dress that is white and gold or blue and black
When shown this image you tend to read ‘THE CAT’ over ‘TAE CHT’ despite the second letter in both words being the same symbol. Why is that? What kind of visual processing is this?
a) top-down
b) bottom-up
This is a b/c it is based on our prev knowlegde of the words The and Cat over Tae and Cht. Therefore a
This is an example of which of the following? Why?
a) top-down
b) bottom-up
a) uses our prev knowledge of the English language to perceive what its saying
