3. Perception

Question 1

distal stimulus vs. proximal stimulus vs. percept

Answer 1

distal stimulus: actual stimulus itself

proximal stimulus: the information
consisting of the reception of the distal stimulus

percept: meaningful interpretation of the proximal stimulus

Question 2

What is one fact that supports distinguishing proximal stimuli from percepts

Answer 2

size constancy

Question 3

what is form perception (gestalt)

Answer 3

distinguishing of the display into objects and background

Question 4

what do subjective contours mean in gestalt psychology for perception

Answer 4

when we simplify a complex display into a simple one, by sometimes imagining edges that arent actually there

Question 5

What some (5) of the Gestalt principles of perceptual organization

Answer 5

Principle of proximity
Principle of similarity
Principle of good continuation
Principle of closure
Principle of common fate

Question 6

Explain top-down vs bottom-up processes

Answer 6

Top-down: Perceiver’s expectations/theories guide the pattern recognition process

Bottom-up: Perceiver starts with small bits of information and combines it to form a percept

Question 7

What are 3 bottom-up models of perception

Answer 7

Template matching
Featural analysis
Prototype matching

Question 8

Describe template matching

Answer 8

Type of bottom up perception model
- we read in patterns and compare them to previously stored patterns (templates)

Question 9

What does the template matching model fail to explain

Answer 9

1. We will need to store an impossibly large number of templates
2. How do templates get created and how they are kept track of
3. Patterns are recognized to be the same even if their stimulus patterns differ (etc. blurriness)

Question 10

Describe featural analysis

Answer 10

Bottom up perception model

We conduct perception by searching and recognizing features, and then recognizing the object as a whole

Question 11

What are some neurophysiological experiments (3) that support featural analysis

Answer 11

Implanting electrodes to the retinas of frogs: noticed that “edge” and “bug” stimuli caused certain cells to fire more frequently

Hubel and Wiesel found evidence of separate horizontal + vertical line detectors in cats and monkeys

Visual search: participants recognize letters by features

Question 12

What was the finding of Neisser’s ZQ visual search task

Answer 12

Participants took longer picking out Z or Q from a group of letters, depending on how similar the letters around them were

Showed that we identified letters by features (featural analysis model)

Question 13

What is Selfridge’s Pandemonium model for feature analysis

Answer 13

Think of a neural network, but instead of feature maps you have feature demons on each layer
And instead of weights you have the volume of demon’s screaming as they communicate between layers

Question 14

What does the feature analysis model fail to explain

Answer 14

What is a feature, and how is this decided?

since an observer would need to have a list before starting perception, and this list can be arbitrarily large, how do we do perception quickly?

Question 15

Describe prototype matching

Answer 15

We match input to a stored prototype: its idealized representation

Question 16

What did Cabeza and colleagues find when giving participants of various edited variations of faces (prototype model)

Answer 16

Participants could form prototypes pretty quickly and were more likely to call a face “old” if it was similar to a previous face they saw

Question 17

What is the context effect in perception processing

Answer 17

For top-down processing
- the speed/accuracy at which we recognize objects can depend on the context
- etc. utensils in a kitchen photo or in a random one

Question 18

Explain the steps of Marr’s model in incorporating top down and bottom up processes

Answer 18

first, we have different independent “modules” that analyzes different things like colour, motion, etc.

1. primal sketch: add light and darkness
2. 2 1/2 D sketch: add shading, textures etc. (bottom up)
3. 3D: add knowledge on real world + meaning (top down)

Question 19

What is change blindness

Answer 19

the fact that we often do not detect changes to an object/scene especially when given different views of it

shows top down processing: we only encode the “gist” of the situation

Question 20

The following experiment by Simons and Levin shows what?

A researcher approaches a person and asks for directions.
Halfway through, two people interrupt between by carrying a door.
You don’t notice that the person you were talking to was then replaced by a completely different person

Answer 20

Change blindness, and specifically the fact that it occurs in real world, not just clips

50% of participants don’t notice

students are more likely to notice than older participants

however, if wearing construction clothing, then less than half of the students noticed

Question 21

What is the word superiority effect

Answer 21

Letters are easier to perceive in a familiar context (words) than in an unfamiliar context or no context

top down processing

Question 22

What are phonemes

Answer 22

sounds (makes up a word)

likened to letters when using feature detection for a word

Question 23

What is the missing letter effect

Answer 23

When trying to find letters, we often miss those used in function words (vs. content words)

function words: for, of, or

Question 24

What is the connectionist model for word perception and how might it explain the word superiority effect

Answer 24

there are layers (features, letters, words) that get activated

having a word has more of the same activation (vs. just a letter) so maybe that’s why we perceive a letter easier in the context of a word

Question 25

What regions of the brain showed greater activity under a PET scan when doing word perception for real and pseudo words

Answer 25

Both hemispheres of visual cortex were active
But there was more activity in left hemisphere + regions in visual cortex when viewing words rather than gibberish

(might be related to semantic processing)

Question 26

what is the constructivist approach to perception

Answer 26

models that assume perception takes place as:
distal -> proximal -> percept

we distort + add to the information of a proximal stimulus to form a percept

in opposition to the direct perception view

Question 27

what is the direct perception view of perception + who led it

Answer 27

James Gibson, in opposition to the constructivist approach

The world already offers a lot of information, and the perceiver does very little work

experiment: participants can recognize people dancing w/ lights attached to their body in the dark

Question 28

What is an affordance

Answer 28

Part of direct perception view

acts/behaviours permitted by objects, places, and events

Question 29

What is Neisser’s perceptual cycle model

Answer 29

attempts to incorporate direct perception + constructivist views

cognitive structures called schemata guide the perceiver to explore. Results of exploration then updates the schemata

Question 30

What is apperceptive agnosia

Answer 30

• very limited visual information
• can see contours (outlines) of objects
• cannot match objects or categorize them
• cannot recognize object if parts of the lineart is missing
• cannot recognize object if in unusual orientation

Question 31

What is asociative agnosia

Answer 31

• can match objects + copy drawings but do so very slowly (point by point, not as a whole)
• cannot name objects they have drawn
• cannot access meaning from a visual description alone

Question 32

What kind of injury causes apperceptive agnosia

Answer 32

bilateral damage to a particular region

Question 33

What kind of injury causes associative agnosia

Answer 33

injury to to the right side of the brain

Question 34

What is prosopagnosia and its injury causes

Answer 34

Inability to EXPLICITLY recognize faces
- implicitly some abilities exist: galvanic skin response (GSR) recorder shows different responses to loved ones vs. strangers
- usually damage to region in right hemisphere (sometimes with some left as well)

Question 35

What is unilateral neglect and what causes it

Answer 35

Caused by damage to one side of parietal cortex, and causes the patient to ignore stimuli that occurs on the opposite side

Question 36

What is synaesthesia

Answer 36

etc. digit to colour

Question 37

What is capgras syndrome

Answer 37

explicit face recognition, but not implicity recognition
- sees the person as an imposter