Perception

Question 1

define

sensation

Answer 1

how our sensory receptors receive and represent stimuli in our environment

Question 2

define

perception

Answer 2

how our brain organizes and interprets sensory information

Question 3

what do visual illusions imply about perception?

Answer 3

it is an active process that our minds perform automatically

Question 4

define

top-down processing

Answer 4

knowledge and expectations influence information-process

Question 5

define

bottom-up processing

Answer 5

raw visual information is processed as is

Question 5

provide an example of top-down processing

Answer 5

possible answers:
1. Bhalla & Proffitt (1999) found that wearing a heavy backpack influenced the perceived slope of a hill
2. wearing swim flippers makes swimming distances seem smaller
3. the color of food affects taste.

Question 5

how do we see 3D objects when the image on our retinas is 2D?

Answer 5

1. the retina contains cells that interpret basic information (eg edges, orientation of lines)
2. the optic nerve extends information to the primary visual cortex (V1)

Question 5

where is the primary visual cortex?

Answer 5

the back of the brain

Question 5

fill in blanks with these words: left visual field, left visual cortex, right visual field, right visual cortex

information from _____ crosses and is processed in the _____________

Answer 5

1. information from left visual field crosses and is processed in the right visual cortex
2. information from right visual field crosses and is processed in the left visual cortex

Question 5

what are occluded and granular objects? how does our brain register these objects?

depth cues

Answer 5

occluded objects are farther back. more granular (detailed) textures are closer. an object of fixed size is bigger when it is closer.

Question 6

what are perceptual constances?

Answer 6

how our perceptions are stable despite changes in environment or context. i.e lightness, size, shape, color

Question 7

how can our brain “see” things as normal when the image on the retina varies?

Answer 7

1. assumptions about light sources (like direction, color, etc.)
2. information from memory
3. we don’t entirely know

Question 8

what is object perception?

identify the processes that occur when looking at a picture

Answer 8

the processes involved in building up a representation of an individual volume of matter in the world
1. indentifying and classifying edges
2. integrating edges
3. filling in missing edge and surface info.
4. unifying object parts
5. segmenting object from background

Question 9

what did hubel & wiesel study?

hint: edge detection

Answer 9

they study single cells and found greater activity from cells that only responded to only one particular orientation of line

Question 10

what is segmentation and grouping?

Answer 10

the brain differentiating which segments are part of the same object and which are diffferent
- must separte figures from ground

Question 11

define

bistable perception

Answer 11

multiple interpretations of one image are possible
- an example of perception being an active process

Question 13

define

proximity (Gestalt)

Answer 13

things that are closer to one another tend to be perceived as connected and part of a whole object, compared to things that are furhter apart

Question 14

define

similarity (Gestalt)

Answer 14

things that are similar in brightness, color, shape, etc. tend to be seen as a single object, rather than separate objects

Question 15

define

closure (Gestalt)

Answer 15

incomplete objects tend to be perceived as wholes
- the parts that form a complete/almost complete object go together

Question 17

define

good continuation (Gestalt)

Answer 17

elements arranged on a line or a curve are perceived as more related than elements not on a line or curve
- i.e Olympics rings

Question 18

define

figure-ground (Gestalt)

Answer 18

elements perceived as either figures (distinct element of focus) or ground (background where figures sit)
- i.e FedEx

Question 19

Law of Pragnanz (Gestalt)

Answer 19

elements are grouped in the simplest way that produces a ‘good figure’

Question 20

define

pattern recognition

Answer 20

ability to identify objects (matching patterns to knowledge)

Question 21

how do we recognize objects?

identify the two steps object recognition

_TM and _TM

Answer 21

STM: represent stimulus in short-term memory
LTM: find representation in long-term memory that matches it

Question 22

what are the three main object recognition theories?

Answer 22

1. templates
2. feature detection
3. structural descriptions

Question 23

define

template theory

Answer 23

a new stimulus is matchd to an internal mental representation of the stimulus (the template)

Question 24

what are the issues with template matching theory?

Answer 24

viewpoint-dependent:
large variability within categories, requiring a new template for each possibility

Question 25

define

feature detection theory

Answer 25

a stimulus is borken down into its features/components to determine what it is

Question 26

describe how feature detection theory might explain how we can recognize an A or a dog

Answer 26

A: two long diagonal vertical lines, point at top, one shorter horizontal line
dog: two ears, four legs, a tail

Question 27

what is the pandemonium model?

Answer 27

• instance of the feature detection theory
• Lindsay & Norman 1972
• suggests that feature ‘demons’ shout when they see their own feature
• ‘demon’s are more like populations of neurons
• primary visual cortex: feature demons
• cortical areas that determine object properites: cognitive demons

Question 28

what is the word superiority effect?

Answer 28

people can more accurately identify letters when they are part of a word than on their own
- example of top-down-processing: knowledge of words influences perception of letters

Question 28

what are some advantages of the feature detection theory?

Answer 28

• doesn’t require a large number of templates and invariant to size, orientation and location -> much more effficient
• explains errors people make during recognition (when images are presented too quickly, ‘B’ demons will shout as loudly as ‘R’ demons which may lead to letter confusuion)
• fits with neural evidence that shows neurons in the primary visual cortex act as feature detectors

Question 29

what are the shortcomings of feature detection theory?

Answer 29

• difficult to define a “feature” (is the feature the letter A or the lines, points, etc)
• can’t explain the word superiority effect (increase in efficiency when letters are in a word)
• entirely bottom-up

Question 31

define

recognition by components theory

Answer 31

stimuli are composed of universal features called geons (36 total geons)
- like how the alphabet can make words, geons create objects

Question 32

what are the properties of geons?

Answer 32

1. vietpoint invariance: can be viewed and interpreted from many different perspectives
2. discriminability: can tell one geon apart from another regardless of the viewing angle
3. robust to noise: can be perceived even when partially obscured/occluded

Question 33

what are the short-comings of the recognition by components theory?

Answer 33

1. some real-world objects are too complex to break down into simple geons
2. need more than structural description to identify things (like size, color, etc)
   - sometimes need additional info to determine fine-grained category differences
3. cannot account for top-down/contextual influences on object recognition