Week5 Sensation&Perception

Question 1

What is sensation

Answer 1

The stimulus detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain

Question 2

What is perception

Answer 2

The active process of organising the stimulus input and giving it meaning

Question 3

Why do we need sensations

Answer 3

They extract information from the environment that we need to function and survive

Question 4

What is Psychophysics? What are the two focuses?

Answer 4

The scientific study of relations between the physical characteristics of stimuli and sensory capabilities
Two focuses: absolute limits of sensitivity and differences between stimuli

Question 5

Define absolute threshold and give an example of human

Answer 5

The lowest intensity at which a stimulus can be detected 50% of the time
Vision : candle flame at 30 miles on a clear, dark night
Smell: one drop of perfume diffuse into the entire volume of a large apartment
(Source: Galanter, 1962)

Question 6

Define Decision Criterion

Answer 6

A standard of how certain they must be that the stimulus is present before they will say they detect it

Question 7

Define Signal Detection Theory

Answer 7

An account of sensory perception that is concerned with the factors that influence humans judgements about sensory stimuli

Question 8

Key factors that affect sensory judgments

Answer 8

Fatigue, expectations, and significance of the stimulus

Question 9

Played and identified?
Played but not identified?
Not played but identified?
Not played and not identified?

Answer 9

Hit
Miss
False alarm
Correct rejection

Question 10

At a value close to the absolute threshold, participants’ and situations’ characteristics influence the decision criterion
If say yes all the time, what to do?
If say no all the time, what to do?

Answer 10

Yes all the time: increase costs for false alarm to increase detection threshold
No all the time: increase rewards for hits or costs for miss to decrease detection threshold

Question 11

Subliminal stimulus

Answer 11

A stimulus that is so weak or brief that although it is received by the senses, it cannot be perceived consciously

Question 12

Define Difference threshold

Answer 12

The smallest difference between two stimuli that people can perceive 50% of the time
(Also referred as just noticeable difference)

Question 13

What does Weber’s Law say

Answer 13

The difference threshold is directly proportional to the magnitude of the stimulus with which the comparison is being made

Question 14

An example of a sensory adaptation that occurs in all senses and its importance

Answer 14

Diminishing sensitivity to an unchanging stimulus
It allows our senses to pick up informative changes in the environment that would be important to our survival

Question 15

What is sensory transduction?

Answer 15

The process whereby the characteristics of a stimulus are converted into nerve impulses

Question 16

Wavelengths that human vision is sensitive to?

Answer 16

Around 400-700nm

Question 17

Protections of eyes and how

Answer 17

Eyelid, eyelashes and eyebrows
Eyelid will close automatically if there is a sudden approach of an object

Question 18

What is pupil and what does it do

Answer 18

An adjustable opening behind the cornea that controls the amount of light that enters the eye
It dilates or constricts using the muscles in the iris

Question 19

Describe iris

Answer 19

The coloured part surrounding the pupil

Question 20

What are lens and what do they do

Answer 20

A flexible structure that becomes thinner to focus on distant objects and thicker to focus on nearby objects
It also causes images to be focused on the inner surface of the back of the eye (retina)

Question 21

Describe accommodation

Answer 21

Focusing the image directly and sharply onto the retina is what determines good all-round vision

Question 22

Describe Myopia (nearsightedness)

Answer 22

Visual image is focused in front of retina (or too near lens)
Occurs because the eyeball is longer than normal

Question 23

Describe Hyperopia(farsightedness)

Answer 23

Image is focused behind retina (or too far from lens)
Lens are not thick enough

Question 24

Retina is

Answer 24

A multilayered light-sensitive tissue at the rear of the fluid-filled eyeball

Question 25

What are Rods cells and Cones cells? When do they function best?

Answer 25

Rods: black and white brightness receptors, dim light
Cones: Colour receptors, bright illumination

Question 26

What is Fovea and what is it responsible for

Answer 26

A small area in the centre of the retina that contains no rods but many densely packed cones
Responsible for most detailed vision

Question 27

Describe distribution of cones

Answer 27

Cones decrease in concentration the further away they are from the centre of the retina
They are either in Fovea or around it

Question 28

Rods and cones have synaptic connections with…

Answer 28

Bipolar cells

Question 29

Bipolar cells are connected to…

Answer 29

Ganglion cells

Question 30

___________ _____________ of ganglion cells are collected into a bundle to form the optic nerve

Answer 30

Long axons

Question 31

Absence of ____________________ where the optic nerve exits the eye creates a blind spot

Answer 31

Photoreceptors

Question 32

Lens reverses image from ____ to ____, _____ to _______ on retina

Answer 32

Right to left
Top to bottom

Question 33

Why rods are very sensitive to low light, but with low acuity (poor details)?

Answer 33

Many rods are connected to just one bipolar/ganglion

Question 34

What are photo-pigments and what do they do?

Answer 34

Protein molecules that allow rods and cones to translate light waves into nerve impulses
They produce a chemical reaction that changes the rate of neurotransmitter release
The greater the change, the stronger the signal passed onto the bipolar and ganglion cells

Question 35

What is dark adaptation

Answer 35

The progressive improvement in brightness sensitivity that occurs over time under conditions of low illumination

Question 36

Which photoreceptor takes longer to regenerate

Answer 36

Rods

Question 37

Route of Visual images from retina to the brain

Answer 37

Retina->optic nerve->thalamus -> primary visual cortex in occipital lobe

Question 38

What are feature detectors in primary visual cortex

Answer 38

Cells within the primary visual cortex that fire selectively in response to visual stimuli that have specific characteristics

Question 39

What does the visual association cortex do

Answer 39

Combines and interprets information

Question 40

How does a stimulus go from bipolar cells to the visual cortex

Answer 40

Stimulus passed on through bipolar cells-> retinal ganglion cells-> they fire an action potential -> message sent directly to the visual relay station in thalamus-> sent to visual cortex