2 Representation in the Visual System

Question 1

What is Kayahara’s ‘Spinning Dancer’ illusion?

Answer 1

Kayahara, involves the apparent direction of motion of the figure. Some observers initially see the figure as spinning clockwise (viewed from above) and some counterclockwise. Additionally, some may see the figure suddenly spin in the opposite direction.

Question 2

Pathway of information into the eye

Answer 2

receptor cells (rods and cones) –> bipolar cells (middle layer) –> ganglion cells –> optic nerve fiber.

Question 3

Cone Mediated vision (phototopic)

Answer 3

Day time in high colour. High acuity colour vision in good illumination.

Question 4

Rod-mediated vision (scotopic)

Answer 4

Night time in low vision. poorer acuity achromatic vision in low-light levels.

Question 5

Distribution of rods and cones in the retina…

Answer 5

Centre - Cones (focusing on image)
Peripheral - Rods

• (Blind spot at 15 degrees (Nasale side of fovea)

Question 6

Convergence in Rods and Cones.

Answer 6

Low in cones (small number of bipolar cells)
High in rods (high bipolar cells)

Question 7

What are Intrinsically Photosensitive Retinal Ganglion Cells (ipRGC)?

Answer 7

Photosensitive and they respond to light. Sensitive to blue light. Utilise photopigment melanopsin (maximally sensitive to blue light)

They have connections through the suprachiasmatic nucleus (SCN)

Not responsible for creating a visual experience, but body clock.

They found this out because blind people still knew if it was day or night.

Question 8

The location of the blind spot in the left eye…

Answer 8

Question 9

Synaptic Transmition… (Photo) maybe update later?

Answer 9

Question 10

Depolarisation of membrane?

Answer 10

= Excitatory postsynaptic potential (EPSP)

Question 11

Hyperpolarisation of membrane?

Answer 11

= Inhibitory postsynaptic potential (IPSP)

Question 12

What is lateral inhibition? (an opponent process)

Answer 12

Lateral inhibition refers to the capacity of excited neurons to reduce the activity of their neighbors. Neurons that are firing inhibit the stimulation of surrounding. Accordingly, only the neurons that are most stimulated and least inhibited respond.

Two systems compete with each other that represent the world.

Question 13

What are match bands?

Answer 13

Mach bands: at the edge between a light and darker area is a dark bank on one side and a light band on the other side. Light and dark one don’t exist.

Question 14

Why does colour not exist out of the nervous system?

Answer 14

All that exists is electromagnetic frequencies

Question 15

Monochromatic View?

Answer 15

black and white. Snakes, rats, mice.

Question 16

Dichromatic View

Answer 16

Only blues and greens.
Most mammals including cats and dogs

Question 17

Trichromatic view

Answer 17

Blues, greens and reds
Humans, apes, old world monkeys

Question 18

How many receptor types do birds, reptiles and fish have?

Answer 18

4

Question 19

How many colour receptors does the mantis shrip have?

Answer 19

12, 8 in visible, 4 in the ultra violet.

Question 20

(Deuteranomaly, most common) Colour blindess

Answer 20

Weak in green

Question 21

Protanopia (colour blindness)

Answer 21

no red.

Question 22

Why do we get colour after image?

Answer 22

Opponent-process theory suggests that colour perception is controlled by the activity of two opponent systems; a blue-yellow mechanism and a red-green mechanism.

As a result, there are some colour combinations we never see.

Question 23

How does homeostasis relate to opponent processes?

Answer 23

Homeostasis is any self-regulating process by which an organism tends to maintain stability while adjusting to the conditions that are best for its survival

Question 24

Opponent processes in motivation?

Answer 24

Approach-Avoidance arises from competition between the drive to pursue reward and to avoid harm.