reverse terms

Question 1

rods more sentive then cones (endency for the peak luminance sensitivity of the human eye to shift toward the blue end of the color spectrum at low illumination levels.) Reds get darker

Answer 1

Purkinje Shift

Question 2

Three lightness perception phenomena explained by (or edge enhancement)

• The Hermann Grid: Seeing spots at an intersection
• Mach Bands: Seeing borders more sharply
• Simultaneous Contrast: Seeing areas of different brightness due to adjacent areas

Answer 2

lateral inhibition

Question 3

Damage to retinal blood vessels causes leakage, neovascularisation and potentially, retinal detachment

Answer 3

Diabetic Retinopathy

Question 4

Disease of old age
Central part of visual field deteriorates
Results in loss of central vision

Answer 4

Macular Degeneration

Question 5

Hereditary retinal degeneration
Starts in retinal periphery
Initial symptom night-blindness and loss of
 peripheral vision, then tunnel vision, then
 total blindness

Answer 5

Retinitis Pigmentosa

Question 6

Eye disease usually associated with increase in intraocular pressure
Untreated can lead to blindness
Several different forms

Answer 6

Glaucoma

Question 7

A disorder of the extraocular muscles in which the two eyes are not aligned with one another, resulting in a double image, which impairs binocular depth perception.

Answer 7

strabismus

Question 8

A condition in which both eyes develop normally but the neural signals from one eye aren’t processed properly, so that fine vision doesn’t develop in that eye.

Answer 8

amblyopia

Question 9

• Cylindrical error
• Cornea is lemon-, rather than orange-shaped
• Point image brought into focus in two places
  e. g. horizontal and vertical lines may not both be in focus

Answer 9

Astigmatism

Question 10

nearsighted, eye is too long, too much optical pwr, focus point is in front of retnia

Answer 10

myopia

Question 11

farsighted, eye too short, low optical pwr,

Answer 11

hyperopia

Question 12

Shadows on the retina thrown by debris within the vitreous humor; perceived as small, semitransparent spots or threads that appear to be floating before the person’s eyes and tend to move with the eyes.

Answer 12

Floaters

Question 13

cloudy lens

Answer 13

Corneal Opacities

Question 14

Opacity of the lens prevents clear vision
Typically occurs later in life, but seen in infants
Corrected by removing lens and using either spectacle correction or intraocular lens implants

Answer 14

Cataract

Question 15

represent a compromise between the method of limits and the method of constant stimuli

Efficient
Avoid observer bias
Avoid errors of anticipation and habituation

Answer 15

The “Staircase” Methods

Question 16

Experimenter has control of stimulus
Several stimulus values chosen to “bracket” assumed threshold (5-9)
Stimuli presented many times in random order
“Psychometric function” derived from proportion of ‘yes’ responses
Can be used to measure both detection and discrimination
-Advantages:
Essentially eliminates observer bias
Reduces adaptation
Gives very reliable results
Eliminates errors of anticipation and habituation
-Disadvantages:
Very inefficient and time consuming
Needs preliminary estimate of threshold to decide on stimulus values

Answer 16

Method of Constants

Question 17

Experimenter has control of stimulus 
Adjust intensity in discrete steps until observer reports that stimulus is just detectable
Typically make adjustments from above (descending series) and below (ascending series)
Can be used to measure both detection and discrimination
-Advantages:
Reduces observer bias
Reduces adaptation
Simple to calculate threshold
-Disadvantages:
Inefficient
Errors of anticipation 
   (“jump the gun”)
Errors of habituation
   (“maintain response”)

Answer 17

Method of Limits

Question 18

Vary location of stimulus among various times or locations
Participant is asked to “locate” the stimulus
Is used in combination with other methods
-Advantages:
Lower thresholds
Avoids observer bias
-Disadvantages:
More stimulus presentations because every trial involves two intervals or locations

Answer 18

Forced Choice Methods

Question 19

Typically, observer has control of stimulus
Adjust intensity of stimulus until target is just detectable
Typically make adjustments from above and below
Can be used to measure both detection and discrimination
-Advantages:
Fast
Avoids boredom
-Disadvantages:
Subject bias
Possibility of adaptation

Answer 19

Method of Adjustment

Question 20

ability to see is poor at first then it studies out and at 5 minutes starts getting progressively better as rods take over

Answer 20

Dark adaption

Question 21

• rod dominated
• sensitive in dim light
• poor visual acuity
• no colour sensation

Answer 21

Scotopic Vision

Question 22

• cone dominated
• insensitive in dim light
• good visual acuity
• good colour vision

Answer 22

Photopic Vision

Question 23

• Difficulty with reaching and grasping objects

- have trouble acting on things, only visually guided, close eyes and is fine

Answer 23

Optic Ataxia

Question 24

V4 colour damage

Answer 24

Achromatopsia

Question 25

inability to perceive motion

Answer 25

Akinetopsia

Question 26

more neurons focused on one task vs. another. number of neurons for center is higher than those of peripheral, in terms of cortex, Low covergence needs lots of neurons

Answer 26

cortical magnification

Question 27

population coding: one cell is ambiguous but if you look at multiple cells, different response patterns of activity can uniquely define 90degrees across multiple cells.

Answer 27

Distributed coding

Question 28

A neuron in the visual cortex that responds to the presence of a line segment with a particular orientation that ends at a particular point within the cell’s receptive field.

Answer 28

hypercomplex cells