Perception

Question 1

Define ‘perception’

Answer 1

Conscious experience that results from stimulation of the senses

Question 2

What are the basic characteristics of perception?

Answer 2

1. Can change based on added information
2. Can involve a process similar to reasoning or problem solving
3. Can be based on a perceptual rule
4. Occurs in conjunction with action
5. Gateway to all other cognition

Question 3

Why is perception difficult for machines?

Answer 3

1. Stimulus on receptors is ambiguous (inverse projection problem)
2. Objects can be hidden or blurred
3. Objects look different from different viewpoints (viewpoint invariance)

Question 4

Inverse projection problem

Answer 4

Task of determining the object that caused a particular image on the retina. Humans typically solve this problem easily as compared to computers

Question 5

Viewpoint invariance

Answer 5

People’s ability to recognize an object seen from different viewpoints

Question 6

Two types of information used by the human perceptual system

Answer 6

1. Environmental energy stimulating receptors

2. Knowledge and expectations

Question 7

Bottom-up processing aka data-based processing

Answer 7

Processing that starts with information received by the receptors (starts at the bottom, when environmental energy stimulates receptors). Sequence of events from eye to brain.

Question 8

Top-down processing aka knowledge-based processing

Answer 8

Processing that involves a person’s knowledge or expectation. Enables people to rapidly identify and determine a story behind a scene.

Question 9

“Multiple personalities of a blob”

Answer 9

Example of top-down processing. What we expect to see in different contexts influences our interpretation of the identity of the “blob”

Question 10

Speech segmentation

Answer 10

Example of top-down processing. The process of perceiving individual words within the continuous flow of the speech signal. If a listener understands the language, their knowledge of the language creates the perception of individual words

Question 11

Transitional probabilities

Answer 11

Example of top-down processing. in speech, the likelihood that one speech sound will follow another within a word. Something we learn without realizing.

Question 12

Likelihood principle

Answer 12

Part of Helmholtz’s theory of unconscious inference that states we perceive the object that is most likely

Question 13

Unconscious inference

Answer 13

Helmholtz’s idea that our perceptions are the result of unconscious assumptions we make about the environment.

Goes hand in hand with his likelihood principle.

Question 14

Max Wertheimer

Answer 14

Led Gestalt Psychologists to reject the idea that perceptions were formed by “adding up” sensations.

Stroboscope created an illusion of movement by rapidly alternating two slightly different pictures

Question 15

Apparent movement

Answer 15

The principle behind the illusion of movement created by the stroboscope.

Occurs when stimuli in different locations are flashed on after another with the proper timing.

Question 16

Three components of stimuli that create apparent movement:

Answer 16

1. One light flashes on and off
2. A period of darkness, lasting a fraction of a second.
3. The second light flashes on and off

Question 17

Why don’t we see the period of darkness during apparent movement?

Answer 17

Our perceptual systems adds something during the period of darkness - the perception of light moving

Question 18

Wertheimer’s two conclusions on apparent movement:

Answer 18

1. Apparent movement cannot be explained by sensations because there is nothing in the dark space between flashing lights.
2. The whole is different than the sum of its parts

Question 19

Gestalt psychologists believe that perception is determined by…

Answer 19

specific organizing principles (aka “intrinsic laws”) built into the system

Question 20

What are the three principles of perceptual organization?

Answer 20

1. Good continuation
2. Pragnanz
3. Similarity

Question 21

Good continuation

Answer 21

States that points, when connected, result in straight or smoothly curving lines that are seen as belonging together.

Objects that are overlapped are seen as continuing behind the overlapping object.

Question 22

Pragnanz

Answer 22

“Good figure”
States that every stimulus pattern is seen in such a way that the resulting structure is as simple as possible.

Ex; Olympic circles are seen as 5 circles, not 9 shapes

Question 23

Similarity

Answer 23

States that similar things tend to be grouped together

Question 24

Regularities in the environment

Answer 24

Characteristics of the environment that occur frequently

Question 25

Physical regularities

Answer 25

Regularly occurring physical properties of the environment.

Ex; there are more vertical and horizontal lines in the environment than oblique (angled) lines

Question 26

Physical regularities: Oblique effect

Answer 26

Vertical and horizontal orientations are perceived more easily than other (slanted) orientations

Question 27

Physical regularities: Light from above assumption

Answer 27

Our perception of illuminated shapes is influenced by how they are shaded, combined with the brain’s assumption that light is coming from above.

Question 28

Semantic regularities

Answer 28

The characteristics associated with the functions carried out in different scenes

Question 29

Semantic regularities: Scene schema

Answer 29

A person’s knowledge about what is likely to be contained in a particular scene. Can help guide attention to different areas of the scene.

Question 30

Regularities in the environment provide information we can use to…

Answer 30

resolve ambiguities

Question 31

Bayesian inference

Answer 31

Our estimate of the probability of an outcome is determined by the prior probability (our initial belief) and the likelihood (the extent to which the available evidence is consistent with the outcome)

Question 32

Experience-Dependent Plasticity

Answer 32

Experience can shape nervous system.

The brain’s function can be tuned to operate best within a specific environment

Empirical evidence: Gauthier - Greeble stimuli

Question 33

Interaction of perception and action

Answer 33

Coordination is continually occurring between perceiving stimuli and taking action towards them.

Ex; picking up a cup of coffee

Question 34

“What” pathway

Answer 34

AKA ventral pathway. Associated with perceiving and recognizing objects

Question 35

Object discrimination problem

Answer 35

Must remember an object based on its shape and choose it when presented with another object after a delay.

This was presented to monkeys in order to conclude that it was associated with the “What” pathway

Question 36

“Where” pathway

Answer 36

AKA dorsal pathway.

Associated with ability to locate objects

Question 37

Landmark discrimination problem

Answer 37

Must remember an objects location and choose that location after a delay.

This was presented to monkeys in order to conclude that it was associated with the “Where” pathway

Question 38

Ungerleider and Mischkin experiment with Monkeys

Answer 38

Studied how removing part of a monkey’s brain (brain ablation) affected its ability to identify an object and determine the objects location

Question 39

Milner and Goodale experiment with perception and action streams

Answer 39

Studied a woman with damage to her temporal lobe. Her behaviour to the tasks showed that there is one mechanism for judging orientation and other for coordinating vision and action

Question 40

Perception pathway

Answer 40

Associated with perceiving and recognizing objects.

Corresponds to the “What” pathway

This was damaged in the woman’s brain

Question 41

Action pathway

Answer 41

Associated with neural processing that occurs when people take action.

Corresponds to the “Where” pathway

Question 42

Mirror neurons

Answer 42

Discovered in monkeys, no evidence for them in humans.

In the premotor cortex, respond when a monkey observes someone else carrying out an action AND when the monkey itself carries out that action

Question 43

Cortical areas in the human brain associated with mirror neuron system

Answer 43

Frontal, parietal, and temporal