lecture 12 - spatial vision

Question 1

spatial vision

Answer 1

the ability to perceive and interpret spatial relationships in our environment, including the location, size and orientation of objects

Question 2

why is spatial vision crucial

Answer 2

it is crucial for navigating the world, recognizing objects and performing everyday tasks

Question 3

spatial frequency

Answer 3

the level of detail present in a visual stimulus, measured in cycles per degree of visual angle

Question 4

high spatial frequency

Answer 4

for fine details

Question 5

low spatial frequency

Answer 5

for broad shapes

Question 6

contrast sensitivity

Answer 6

the ability to detect differences in luminance between areas of lightness and darkness. how well you can discriminate the lighter sections from darker sections.

Question 7

why is contrast sensitivity important

Answer 7

it is important for us to be able to detect objections, edges in particular

Question 8

measuring contrast sensitivity

Answer 8

present patches with different levels of contrast and see how much you can reduce the contrast before the lines disappear

Question 9

measuring contrast sensitivity - low threshold

Answer 9

if you can just see the lines at a low contrast level = high sensitivity

Question 10

measuring contrast sensitivity - high threshold

Answer 10

if you can just see the lines at a high contrast level = low sensitivity

Question 11

Campbell et al 1973

Answer 11

while cats are more sensitive to lower spatial frequency (useful for the detection of motion), some raptors are sensitive to higher spatial frequencies

Question 12

fourrier analysis

Answer 12

when processing the images you see, the visual system relies on different channels which are each specialised for different spatial frequencies at different orientations

Question 13

oblique effect - Campbell et al 1966

Answer 13

showed that we are differently sensitive to different orientations. we are most sensitive to horizontal and vertical orientations and much less so to diagonal orientations

Question 14

different levels of vision

Answer 14

foveal/central
parafoveal
peripheral

Question 15

foveal/central degrees

Answer 15

1 - 5 degrees

Question 16

parafoveal degrees

Answer 16

up to 8 degrees

Question 17

peripheral degrees

Answer 17

beyond 8 degrees

Question 18

eccentricity

Answer 18

The angle between where you are looking at and areas in you peripheral is measured in degrees

Question 19

central vision

Answer 19

high acuity, colour perception and focused attention

Question 20

high accuity

Answer 20

provides the highest visual resolution, allowing us to see fine details which is essential for reading and recognising faces.

Question 21

colour percpetion

Answer 21

rich in cone cells, making it sensitive to colour and enabling colour discrimination

Question 22

focused attention

Answer 22

where we direct our gaze for tasks requiring precise focus, as this area provides the sharpest, most detailed view

Question 23

parafoveal vision

Answer 23

supporting reading and scanning allows us to move our eyes more efficiently across lines of text. peripheral preview for focus shift gives us hints about what is in the near peripherary, enabling quick, accurate shifts in focus

Question 24

peripheral vision

Answer 24

detecting motion, spatial awareness and low light sensitivity

Question 25

detecting motion

Answer 25

highly sensitive to motion which helps us to detect movement in the environment. an evolutionary advantage for detecting threats or changes in our surroundings

Question 26

spatial awareness

Answer 26

contributes to spatial orientation via the optic flow, allowing us to navigate our environment and maintain balance

Question 27

low light sensitivity

Answer 27

relies more on rod photoreceptors, which are better suited for low-light conditions, giving us greater night vision and awareness in dim environments

Question 28

crowding

Answer 28

r (target) --> are (a and e are the flankers, r is the target)

Question 29

To et al 2010

Answer 29

how well participants can see a difference in images when they are presented (a) alone, (b) amongst identical flankers at close distance, (c) amonst repetitions of a different flanker at mid distance, and (d) amongst several different flankers at a far distance

Question 30

what did To et al 2010 find

Answer 30

flankers made no difference in central vision, but led to significant crowding in the peripherary. the most effective flankers were those similar to the targets. crowding effects were stronger when the target flanker distances were short

Question 31

Geiger and Lettvin 1981; Lorusso et al 2004

Answer 31

individuals with developmental dyslexia can experience less crowding in the periphery, but more in central vision compared to controls

Question 32

Castaldi et al 2020

Answer 32

showed that participants with developmental dyscalculia (DD) experienced more crowding compared to controls

Question 33

Why is peripheral vision useful?

Answer 33

detecting sudden changes and movements and triggering foveation towards or avoidance of, stimuli entering the field. the peripheral is essential for maintaining balance