Wk 11 - Space Perception

Question 1

Barn owls are good sound localisers because…

But…

Answer 1

Dense feathers on the face act like a pina – filtering/focussing all the sounds
Left auditory canal is lower than right – vertical separation gives time difference based on objects elevators
Can’t hunt in total darkness – still need some vision in order to navigate

Question 2

Tentmaking bats can hunt in total darkness because of...(x1)
Describe process (x3)

Answer 2

Echolocation
Vocalising at 30 kHz, listening for the 60 kHz they get back
Large portion of inferior colliculus is adapted to processing 60 kHz, grey region is all other frequencies
Just like our visual rep in cortex for the fovea

Question 3

Visual Vernier Acuity test measures…(x1)

And involves…(x1)

Answer 3

Spatial acuity

Two lines, offset slightly, Ps estimate which line is to the right, left of bottom line

Question 4

Echolocation in blind people has been measured using…(x2)

Finding…(x3)

Answer 4

Auditory Vernier task
Clicking in front of targets, ID whether target B is left/right of target B
Same curved results as methods of constant stimuli
Some Ps JND was as low as 1 degree, up to about 8 – whole group average was under four degrees..
Performance relative to age – better at it if blind from infancy

Question 5

Comparisons of spatial acuity through vision and echolocation have found that…(x3)

Answer 5

Visual threshold is about 5 seconds of arc
Blind people accurate to about 1 degree, but
This is equivalent to bats, and to sighted peripheral visual acuity

Question 6

Neural correlates of human echolocation have been established in study involving…(x1)
Finding/concluding…(x2)

Answer 6

Blind people in fMRI, listening to same clicking sounds they make when echolocating
Activity in contralateral occipital lobe -
Analogous with visual processing

Question 7

Visual convergence is a process by which…(x3)

Answer 7

Small angle far away, eyes cross more/converge as the angle increases/object is closer
Is a binocular distance cue in visual system, which
Knows about the tension in ocular muscles – a proprioceptive sense about eye posture

Question 8

Visual accommodation is…(x2)

And is tied to convergence in that…(x3)

Answer 8

Lens accommodation changes – thin for stuff in distance,
But need to bend light more to maintain focus for near objects, so fattens up
Fatness of lens hard wired to change with convergence
Cover one eye, move stimulus along line of sight, lens fattens in order to keep focus on it,
And other eye turns too

Question 9

Binocular disparity is…(x2)
Resulting in …(x1)
And useful in…(x1)

Answer 9

Lateral separation gives slightly different view – horizontal disparity
Very powerful depth cue, gives accurate relative depth perception
Disparity detectable at about 5seconds
Breaking camouflage

Question 10

The first stereoscopes functioned by…(x2)

Demonstrating…(x1)

Answer 10

Looking in at mirrors with different eyes
Brain puts it together into 3D image
The use of horizontal images in depth perception

Question 11

Stereopsis is…

Answer 11

Perception of depth and 3D that arises from binocular vision

Question 12

Random dot stereograms function due to…(x2)

Demonstrating that…(x2)

Answer 12

When you look with one eye, no evidence of square form
Only visible when combining input of two eyes
Binocular disparity is distinct mechanism for depth perception (not just enhancement of other cues),
And that it is purely cortical visual process – ONLY after combined inputs

Question 13

Theoretical horopter is…(x1)

Answer 13

Hypothetical arc that would be formed by our focal point rotating around our head

Question 14

Uncrossed disparity occurs for…(x1)

And is thus named because…(x1)

Answer 14

Objects FAR away, beyond our focal point

You’d have to uncross your eyes to change fixation point

Question 15

Crossed disparity occurs for…(x1)

And is thus named because…(x1)

Answer 15

Objects NEAR, closer than our focal point

You’d have to cross your eyes more to change fixation point

Question 16

Patterns/function of binocular stimulation of receptive fields (x3)

Answer 16

Binocular neurons in striate cortex are linked from from similar retinal area in each eye
Firing of two such neurons upon stimulation by object within view
Tells us about relative position to fixation point (depth)

Question 17

Panum’s fusional area is…(x3)

Answer 17

A region around the visual empirical horopter
Within which objects perceived as single
Double vision for those outside this area

Question 18

Human visual spectrum is…(x4)

Answer 18

380 nm - violet, through
500 nm - blue/green
600 nm - green/yellow (toward orange)
760 nm - red

Question 19

Physical properties of light, wavelength and intensity, correspond to psychological characteristics…(x2)

Answer 19

Colour and brightness

Question 20

Physical description of light…(x2)

Answer 20

Is a particle (photons), and

Wave (wavelength determines colour)

Question 21

Monochromatic and polychromatic light are…(x2 plus egs)

Answer 21

Single (eg laser), and
Multiple wavelengths (eg white light, sunlight)

Question 22

The subjective experience of colour is described through..(x3)

Answer 22

Hue - the colour itself (red, blue, green, etc).
Saturation - purity or vividness of the colour
Brightness - the perceived intensity of the coloured light

Question 23

Trichromatic cones activate for…(x3)

Based on their…(x1)

Answer 23

Short (blue)
Medium (green), and
Long (red) wavelengths
Relative absorption of particular wavelength

Question 24

Young-Helmholtz Trichromatic Theory holds that…(x1)

Eg (x3)

Answer 24

Colour perception is based on the relative activity of each of three cone types
Eg violet almost entirely short wavelength receptors, red almost entirely long, others proportionally in between

Question 25

Young-Helmholtz Trichromatic Theory was useful in accounting for…(x3)

Answer 25

Colour mixing of light,
Deficits like red/green colour blindness
Metamers – where physically distinct stipulations experienced as the same thing, so same patterns of neural response from different wavelength combinations

Question 26

Young-Helmholtz Trichromatic Theory doesn’t account for…(x1 plus eg)

Answer 26

Afterimages

Fixating on central dot of blue/black maple leaf design, becomes Canadian flag when image disappears suddenly

Question 27

Hering’s Opponent Process Theory is that…

Answer 27

Red/green, black/white and blue/yellow perceptual mechanisms are paired in an antagonist relationship -
Each responds in opposite ways to different wavelengths or intensities of light.

Question 28

Dual Process Theory holds that…(x2)

Answer 28

Young-Helmholts Trichromatic processing occurs at receptor level
Hering’s Opponent Process occurs at receptive field level (ganglion, LGN)

Question 29

Evidence for opponent cells in retina and LGN was found in…(x2)

Answer 29

Opposing electrical signals in colour vision in carp and rhesus monkeys, respectively

Question 30

Describe Type 1 colour opponent cell receptive fields, (plus egs x2)

Answer 30

Concentric on/off regions in ganglion cells

Eg on-centre red/green-surround off, on-centre blue/off-surround yellow, and vice versa

Question 31

Red/green opponent processing cells function by…(x3)

Answer 31

Medium and long wavelength receptors
And a red on/green off neuron
Gets excitatory signal from long, and inhibitory from medium wavelength

Question 32

Blue/yellow opponent processing cells function by…(x5)

Answer 32

Short, medium and long wavelength receptors
Gets excitatory from short (blue) receptor,
Inhibitory yellow input has to be combined medium/long input, because light is in between the two
So yellow equally stimulates M and L wavelength receptors,
Which then converge with excitatory input in horizontal cell, A,
Which then sends inhibitory signal to the BY neuron/ganglion cell

Question 33

Describe Double Opponent Cell receptive fields (x4)

Answer 33

Needs a specific pattern of illumination for maximum firing
Diffuse red or green light means no response
Thought to be good for edges, and particularly edges of food
They could then feed into particular simple cells that detect eg red contours on green backgrounds

Question 34

Edwin Land’s Theory of Colour Vision is that…(x5)

Answer 34

Reporting colour stays constant despite changes to amounts of wavelengths reflected
Not necessarily physical stimulus driving perception, but ratio of relative reflection
So if presented each colour patch in isolation, perception changes
This is colour constancy –perceptually stable no matter how we encounter them
Colour vision would be useless otherwise, if eg apple was different colour at different time of day

Question 35

The Great Dress Colour Debate, 2015, stems from the ways our impression of colour is formed…(x4)
Telling us that…

Answer 35

Composition of light entering eye, and
Assumptions about composition and position of illumination source (eg daylight/other), and
Re reflectance of object, and
Composition of any intervening material (filters, lenses)
At highest stages of processing, assumptions on environment influence colour perception

Question 36

Fear relevant stimuli are those that are…(x1 plus egs x2)

And it is adaptive for these…(x1)

Answer 36

Frequently associated with danger in the natural environment
Snake, spiders
To have priority in our attentional and cognitive systems

Question 37

The capturing of attention by fear-relevant animals is shown in studies involving…(x3)
Finding…(x1)
Concluding…(x2)

Answer 37

Ps fixating on central dot, while fear ir/relevant animals show simultaneously on each side
Followed by a dot on one side
Measure RT for ID of dot
Significant interaction between fear-relevant stimulus and dot location (valid over invalid trials)
Affective content of stimuli can influence our attention.
Fear-relevant animals can involuntarily capture our visual attention.

Question 38

Strengths of our in-class experiment on attention and fear-relevant stimuli…(x3)

Answer 38

Realistic animal photos
Spiders and snakes paired with similar-looking non-dangerous creatures.
Had half the targets on the left and half on the right to eliminate handedness effects

Question 39

Limitations of our in-class experiment on attention and fear-relevant stimuli…(x4)

Answer 39

Too few trials (10 per condition)
Lots of extraneous variables (colour, background, posture of animals, etc) could add noise or confound
Didn’t measure people’s fear of snakes/spiders
Some scary creatures were camouflaged.

Question 40

The relationship between memory and the amygdala is…(x2)

Answer 40

Affective content of stimuli can influence how likely we are to remember them.
The amygdala is involved in processing affective stimuli.

Question 41

Prepared learning means that…(x1)

And is…(x1)

Answer 41

Fear conditioning is stronger for certain stimuli, notably dangerous creatures
Irrational - fear response will continue even if told you will no longer be shocked

Question 42

Blink-startle magnitude (fear-potentiated startle) is…(x2)

Answer 42

How intense the blink is when startled

Faster when afraid

Question 43

Prepared learning for other-race faces was tested by…(x3)
Finding…(x1)
Concluding…(x2)

Answer 43

Ps conditioned to fear Caucasian vs Chinese faces
Then received instructions that shock would stop, or didn’t
Measured blink-startle and GSR during extinction
Fear learning during acquisition
Resistance to extinction only in Chinese-no instruction group
That it was not irrational, as cognition can overcome it, therefor
Not prepared learning, and cognition can influence our affective response