2. Vision

Question 1

Law of Proximity

Answer 1

elements close together perceived as one

Question 2

Law of Similarity

Answer 2

similar objects are grouped together

Question 3

Law of Good Continuation

Answer 3

elements that follow on the same pathway are grouped together

Question 4

Law of Subjective Contours

Answer 4

perception of shapes that are not actually present

Question 5

Law of Closure

Answer 5

figures tend to be perceived to be more complete than they actually are

Question 6

Gestalt Principles

Answer 6

“gaps” in knowledge are filled by gestalt principles; help w/ object recognition

Question 7

Bottom-Up Processing (def, steps)

Answer 7

• Refers to object recognition by parallel processing and feature detection; brain takes individual sensory stimuli and combines them together to create a cohesive image before determining what the object is
• (DATA-DRIVEN)
• Steps:

1. Stimuli
2. Attention
3. Perception
4. Thought processes
5. Decision
6. Response of action

Question 8

Top-down processing (def, steps)

Answer 8

• driven by memories and expectations that allow the brain to recognize the whole object and then recognize the components based on these expectations
• CONCEPTUALLY DRIVEN
• allows us to quickly recognize objects w/o needing to analyze their specific parts

Question 9

*Steps of Visual Processing

Answer 9

• LGN –> SUPERIOR COLLICULUS –> OCCIPITAL LOBE
• Involves:
  
  • Lateral geniculate nucleus of the thalamus: “light”; a relay center in the thalamus for the visual pathway
  • Superior colliculus: autonomic reflexes; orients vision
    
    • *inferior colliculus orients in response to sound
  • Visual cortex (occipital lobe):

Question 10

Which optic fibers cross over at optic chiasm?

Answer 10

Nasal fibers crossover @ optic chiasm, so PERIPHERAL VISION would be affects by a lesion @ optic chiasm (e.g. pressure by pituitary tumor)

Question 11

Which fields of vision are perceived by the temporal fibers?

Answer 11

The temporal fibers see the nasal fields of vision

Without the temporal fibers, you’d only have peripheral vision

Question 12

What is the optic deficit seen with pituitary tumor/pressure on optic chiasm?

Answer 12

You would lose the peripheral vision; the pituitary tumor puts pressure on optic chiasm, which is where nasal fibers cross over –> nasal fibers see peripheral fields of vision –> w/o these, you’d only have central vision

Question 13

What is the optic deficit seen if there was a lesion in the RIGHT OPTIC NERVE?

Answer 13

The right optic nerve wouldn’t be able to send any information to the visual cortex, so the right eye would be blind

Question 14

Bipolar cells

Answer 14

receive direct input from rods/cones, highlight gradients, and synapse w/ ganglion cells

Question 15

*Amacrine and Horizontal cells

Answer 15

both types of cells receive info from multiple retinal cells; allow for edge detection and contrasts

Question 16

Ganglion cell

Answer 16

receives info from many cells; they group together to form optic nerve

Question 17

pupil

Answer 17

a hole located in the centre of the iris of the eye that allows light to strike the retina

Question 18

why does the pupil appear black?

Answer 18

It appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that mostly miss exiting the narrow pupil

Question 19

Cornea

Answer 19

a clear, domelike window in the front of the eye, which gathers and focuses incoming light

Question 20

anterior chamber

Answer 20

lies in front of the iris

Question 21

posterior chamber

Answer 21

between the iris and the lens

Question 22

choroid

Answer 22

produces the aqueous humor that bathes the front part of the eye before draining into the canal of Schlemm

Question 23

iris

Answer 23

colored part of the eye; consists of 2 muscles (dilator and constrictor pupillae)

Question 24

two sets of blood vessels in the eye

Answer 24

• choroidal vessels: a complex intermingling of blood vessels between the sclera and the retina
• retinal cells

Question 25

retina

Answer 25

• innermost layer of the eye
• contains the actual photoreceptors that transduce light into electrical information the brain can process

Question 26

lens

Answer 26

• lies right behind the iris
• helps control the refraction of the incoming light

Question 27

ciliary muscle

Answer 27

component of the ciliary body; contraction of the muscle is under parasympathetic control

Question 28

Accommodation

Answer 28

as the ciliary muscle contracts, it pulls on the suspensory ligaments and changes the shape of the lens

Question 29

aqueous humor

Answer 29

produced by choroid; bathes the front part of the eye before draining into the canal of Schlemm

Question 30

vitreous humor

Answer 30

transparent gel that supports the retina; found behind the lens

Question 31

Duplicity theory of vision

Answer 31

states that the retina contains 2 kinds of photoreceptors; those specialized for light-and-dark detection, and those specialized for color detection

Question 32

fovea

Answer 32

• centermost point of the retina; contains ONLY CONES
• visual acuity is best here
• most sensitive to normal, daylight vision

Question 33

Connections of visual cells

Answer 33

• Rods and cones connect w/ bipolar cells –>
• bipolar cells synapse w/ ganglion cells –>
• ganglion cells group together to form the optic nerve