Lec 2

Question 1

What does the perceptual process involve?

Answer 1

• A distal stimulus
• Processing at the receptor level (i.e. transduction)
• Processing at the neuronal level
• Top-down processing that gives rise to a
particular interpretation/meaning
• Some accompanying behavioural response (e.g.
action)

Question 2

What is the distal stimuli?

Answer 2

Environmental stimuli are all objects in
the environment that are available to an
observer

Question 3

Describe proximal stimuli

Answer 3

When an observer selectively attends
to an object, receptors respond to the
distal stimulus, resulting in the
generation of internal representations

Question 4

Describe the principle of representation

Answer 4

Everything a person perceives is based
not on direct contact with stimuli but rather on representations of stimuli
that are formed on the receptors and the resulting activity in the
person’s nervous system

Question 5

Describe the principle of transformation

Answer 5

The representations of stimuli in our
environment which we construct are transformed, or changed, between
the original distal stimulus and the eventual perception they give rise to

Question 6

What are sensory receptors?

Answer 6

Cells specialized to
respond to environmental energy

Question 7

Give an example of sensory receptors in regards to vision

Answer 7

with vision, a critical element involves
visual pigments reacting to light)

Question 8

What is transduction?

Answer 8

The conversion of environmental energy into nerve
impulses during receptor processing

Question 9

What is neural processing?

Answer 9

changes that occur as signals are
transmitted through the
neurons in our brains

Question 10

What is bottom up processing?

Answer 10

based on incoming stimuli from the environment
• Sometimes referred to as ‘data-based processing’

Question 11

What is top down processing?

Answer 11

ased on the perceiver’s previous knowledge (i.e. cognitive factors)
• Sometimes referred to as ‘knowledge-based processing’

Question 12

What three relationships are involved in the perceptual process?

Answer 12

A. Stimulus -> Behaviour
B. Stimulus -> Physiology
C. Physiology -> Behaviour

Question 13

When does the stimulus - behaviour relationship occur?

Answer 13

Between steps 1&2 and steps 5-7

Question 14

Where does the stimulus - physiology relationship occur?

Answer 14

Between steps 1 and 2 and steps 3 and 4

Question 15

Where does the physiology - behaviour relationship occur?

Answer 15

Between steps 3 & 4 and steps 5-7

Question 16

Break down the oblique effect using the 3 relationships

Answer 16

S - B: Perceiving the orientation of lines as spacing gets narrower

S-P: Neural processing of the lines

P-B: Identification of v and h lines is better (oblique effect)

Question 17

What is the electromagnetic spectrum?

Answer 17

The spectrum of all known electromagnetic radiation spanning from short gamma rays to long radio waves.

Question 18

How does the eye work?

Answer 18

• Light enters the eye through the pupil and is focused by the cornea and lens to a
sharp image on the retina
• Rods and cones are visual receptors in the retina that contain visual pigment
• The optic nerve carries information from the retina toward the brain

Question 19

How do rods and cones differ?

Answer 19

Two ways (physically): shape and distribution

Shape

• Rods: large and cylindrical
• Cones: small and tapered

• Distribution across the retina

• Fovea consists solely of cones

• Peripheral retina is mostly rods (but also contains some cones)

Question 20

Describe macular degeneration

Answer 20

: Fovea and
small surrounding area are destroyed
(has particular implications for high
acuity vision)
• Creates a ‘dead zone’ on the retina
• Most common in older individuals

Question 21

Describe retinitis pigmentosa

Answer 21

Rods are
destroyed first (has particular
implications for night vision)
• Foveal cones can also be attacked
• Linked to genetic causes
• Severe cases can result in complete
blindness

Question 22

What is the blind spot?

Answer 22

The location where the optic nerve exits the eye contains no receptors

Question 23

Describe the cornea

Answer 23

fixed, accounts for about 80% of the
focusing power of our eye

Question 24

Describe the lens

Answer 24

adjusts shape for object distance, accounts for
the other 20%

Question 25

What’s accommodation?

Answer 25

Accommodation occurs when ciliary muscles are tightened
• This causes the lens to thicken
• Light rays then pass through the lens more sharply, allowing
for near objects to be focussed on the retina and thus
forming a clearer image

Question 26

Describe myopia

Answer 26

Myopia (AKA ‘nearsightedness’) refers to the
inability to see distant objects clearly

• Occurs when the image gets focused in front of the
retina

• Can be caused by:

• Refractive myopia: cornea or lens bends too
much light

• Axial myopia: eyeball is too long

Question 27

Describe hyperopia

Answer 27

the inability to see nearby objects clearly

• Occurs when the image gets focussed behind the retina
• Usually caused by an eyeball that is too short
• Constant accommodation for nearby objects can lead to eyestrain and headaches

Question 28

Describe presbyopia

Answer 28

when the lens can no longer adjust for
close objects
• Caused by hardening of lens and weakening of ciliary muscles
• Corrective lenses are needed for close activities, such as reading

Question 29

Describe visual transduction

Answer 29

The outer segments of receptors contain visual pigment molecules, which
consist of two components:

1. Retinal: a light sensitive molecule
2. Opsin: a large protein

• Visual transduction occurs when
the retinal absorbs one photon,
causing it to change shape (a
process referred to as
isomerization)

Question 30

What is dark adaptation?

Answer 30

the process of increasing visual sensitivity after switching
from high to low-level lighting conditions

Question 31

Describe the dark adaptation curve

Answer 31

• The dark adaptation curve can be determined using the following general approach:
1. An observer starts in a lit room and becomes ‘light adapted’
2. The lights are then turned off, at which point the observer adjusts the intensity of
a test light until it is just barely visible. This determines their sensitivity at the
beginning of the dark adaptation curve
3. As time passes, they continue to readjust the intensity of the test light (again,
until it is just barely visible) to plot the change in sensitivity across time