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Psychology 2B > Perception > Flashcards

Perception Flashcards

1
Q

What is sound?

A

Waves of changing pressure travelling through air

Physical, measurable properties into perceptual experience which is more useful to navigate environment

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2
Q

What are the two features of a pure tone?

A

Amplitude and Frequency

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3
Q

What is amplitude?

A

Maximum air pressure in each cycle

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4
Q

What is frequency?

A

The number of cycles of changing air pressure per second

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5
Q

What is a pure tone?

A

Perceived pitch is equivalent to frequency

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6
Q

What are natural sounds?

A

Natural sounds consist of pure tones of many frequencies added together

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7
Q

How are pitch and frequency linked?

A

Higher the physical frequency, the higher the perceptual pitch

(increased number of cycles = increased perception)

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8
Q

How is amplitude and volume linked?

A

Larger the amplitude, the louder it is perceived

Increased amplitude is 10x causes loudness to increase approximately 4 times

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9
Q

How is sound perceived in the ear?

A

Change in air pressure through auditory canal

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10
Q

What is the cochlea?

A

Cochlea is a fluid-filled, snail-shaped structure that contains sensory receptor cells of the auditory system

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11
Q

How does auditory transduction occur in the ear?

A

Cochlea has basilar membrane which contains hair cells
Depending on where the hairs are on the membrane will help tell us what the frequency is

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12
Q

What do the hairs on the basilar membrane do?

A

Mechanoreceptors
Transduce vibration of basilar membrane
Send electrical signals to the brain through auditory nerve

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13
Q

What is the process of auditory conduction?

A

Sound waves travel along the auditory canal and strike the tympanic membrane, causing it to vibrate.
This vibration results in movement of the three ossicles
As the ossicles move, the stapes press into a thin membrane of the cochlea known as the oval window
As the stapes presses into the oval window, the fluid inside the cochlea begins to move, which in turn stimulates hair cells, which are auditory receptor cells of the inner ear embedded in the basilar membrane
The basilar membrane is a thin strip of tissue within the cochlea.

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14
Q

What is place coding of sound frequency (in the cochlea)?

A

Each place of the basilar membrane vibrates to a particular frequency

Frequency is highest at the base (oval window), lowest at the tip (apex) of the cochlea

Each hair cell signals the amplitude of one narrow range of frequencies in the sound

Perception of loudness is based on the firing rate of the hair cells
The more the membrane stretches/bends, the more they fire

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15
Q

What is the range of frequencies in adult hearing?

A

Maximum range of frequencies which a person can hear is approximately (20HZ to 20 kHZ)
Decreases with age

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16
Q

What are the three physical dimensions of sound and what do they each determine what we hear?

A

Frequency - Perception of pitch
Amplitude - Perception of loudness
Complexity - Perception of timbre

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17
Q

What are the different theories of frequency?

A

Temporal theory → Asserts that frequency is coded by the activity level of a sensory neuron

Place theory → Different portions of the basilar membrane responses to the sounds of different frequencies

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18
Q

What is meant by harmonic structure?

A

E.g. C4 on piano has a mixture of tones - not just one pure tone but a mixture

Complex periodic sounds with a harmonic structure
Frequencies in the sound are all integer multiples of a single number, the least common denominator (LCD) of the component frequencies
Example: 250 = 1 x 250, 500 = 2 x 250
Complex sounds in which all components share in integer lCD have harmonic structure

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19
Q

What is meant by fundamental frequency?

A

Lowest-frequency component on sound

Can work out fundamental frequency by the rest of the timbre sound (e.g. if first fundamental frequency is not present)

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20
Q

What is auditory masking?

A

Producing a sound to mask another (e.g. cough to mask a fart)

Needs to be louder than sound you’re trying to mask and a similar pitch

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21
Q

What are the gestalt principles of visual perception?

A

The classic principles of the gestalt theory of visual perception include similarity, continuation, closure, proximity, figure/ground, and symmetry & order

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22
Q

What is meaning of V1 in relation to the visual aspect of the brain?

A

V1 is the first of the cortical regions to receive and process information and also the best-understood portion of the visual cortex

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23
Q

What are the two parallel cortical streams?

A

Dorsal Stream (to superior parietal lobe)

Ventral Stream (to inferior temporal lobe)

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24
Q

How do the two parallel cortical streams differ?

A

The ventral stream is (the pathway) involved in the perception of information about objects (vision for perception)

The dorsal stream processes information to guide actions (vision for action).

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25
Q

What is the aim of visual perception?

A

Visual perception is about transforming the patterns of light that enters our eyes into some kind of representation of the world that helps us recognize and interact with the objects and people around us

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26
Q

How can visual perception occur?

A

Break up world into little pieces (such as colour and motion)
Put it back together

27
Q

What are some examples of specialised areas in the human cortex that respond to certain visual stimuli?

A

FFA → Fusiform Face Area - Responds to faces more than other objects

PPA → Parahippocampal Place Area - responds preferentially to places, such as pictures of houses

EBA → Extrastriate Body Area → Specifically involved in the perception of body parts

28
Q

What is the grandmother cell hypothesis and what does it suggest about visual perception?

A

Grandmother cell hypothesis - single-cell for each recognition (e.g. particular cell that recognizes your grandmother)

29
Q

What are the features of the dorsal system?

A

The ‘where’ system, binocular information
Visual control of movement (milner and goodale, 1995)
Egocentric
Unconscious

30
Q

What are the features of the ventral system?

A

The ‘what’ system
Identification of objects and events
Allocentric
Conscious

31
Q

What was Milner & Goodale (1995) experiment to show evidence for the dorsal stream?

A

Optic ataxia (damage to dorsal stream)

No difficulty identifying visual stimuli

Difficulty moving towards target

More difficulty in pointing without delay (‘immediate’)

It results from optic ataxia from lesions to posterior-superior parietal cortex: mis reaching (c), hand posture problems(b) and normal subject (a)

If you have optic ataxia - can say what angle your hand should go but cannot actually do it

32
Q

What was Milner & Goodale (1995) experiment to show evidence for the ventral stream?

A

Visual agnosia (Patient DF - Milner & Goodale, 1995) - Damage to ventral stream
Incapable of recognising faces, objects, shapes and sizes
Capable of drawing from memory
Incapable of copying picture of recognising own drawing

Patient DF = damage on ventral stream
Negotiates obstacles during locomotion
Poorly estimates height of obstacles (verbal response)
Highly proficient at grasping - appropriate hand orientation and grip aperture

Evidence from healthy participants - shows difference between recognition and action
Couldn’t hold letter in right orientation but when doing the action of the task it works

Health PPT are offered a stimulus
Verbal response (judging distance, size)
Motor Response (point, reach and grasp)

33
Q

What is the Ebbinghaus illusion?

A

See lecture notes for image (two same size dots in middle of large dots and middle of small dots)

Verbal response more influenced by the illusion than motor response (Aglioti et al. 1995)

As your aperture (finger distance) stays the same for both circles even though you perceive them as different sizes verbally

Need to consider both streams in experimental designs

34
Q

What is meant by our perceptual system?

A

Our perceptual system = Evolved to reconstruct reality in a way that is biologically useful (e.g. to construct colour - bats echolocation may be coloured in their perception)

Often learn most about how complex system works by studying situations where it makes mistakes

35
Q

What is change blindness?

A

Change blindness is a phenomenon of visual perception that occurs when a stimulus undergoes a change without this being noticed by its observer

Shows there are remarkable gaps in our perception

Masking an image means we are less likely to notice a change

Our interpretation of the visual field = Much sparser than subjective experience of “seeing” suggests

Cannot process everything that is projected onto the retina

e.g. Simon and Levin study at a college

36
Q

What is attention?

A

William James (1890) → It is the taking possession by the mind, one out of several possible objects or trains of thought. Focalization, concentration, and consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others
It is used and referred to many different kinds of mechanisms

37
Q

What are the different varieties of attention?

A

External → Attending to stimuli in the world
Internal → Attending to one line of thought over another or selecting one response over another
Overt → Directing a sense organ toward a stimulus, like pointing your eyes of turning your head
Covert → Attending without giving an outward sign you are doing so
Divided → Splitting attention between two different stimuli
Sustained → Continuously monitoring some stimulus

38
Q

What is visual attention?

A

The selection of some visual stimulus or set of visual stimuli at the expense of others for further visual and cognitive analysis and often for the control of behaviour

39
Q

What are the two competing explanations of visual attention?

A

Space based model vs object based

Object based is more common

40
Q

What is the spotlight metaphor? (space based model of visual attention)

A

Attention is like a spotlight - moves about and allows us to selectively attend to parts of the visual world

A model of visual attention that likens the focus of attention to a spotlight. Information outside of the spotlight is presumed not to receive processing that requires attention.

Posner (1980) → Enhanced processing/detection occurs within this ‘spotlight’
Attention is directed towards ‘space’ according to spotlight model - then star shown - reaction time measured to see that curing attention to particular area of space reduces response time compared to when an alternative space is cued

41
Q

How does orienting attention to a particular location alter visual perception?

A

Posner (1978), Posner (1980), Posner, Davidson & Snyder (1980) examined the effect of visually precueing regions of space on detecting the presence of a potential target
Wanted to know if causing a shift of attention to a specific location in space improved processing of the subsequent stimulus
Examined covert shifts of attention
No eye-movements were allowed

42
Q

What is a problem for the spotlight theory?

A

Attention appears to be object-based, not location based
E.g. image of house and other object overlaid but only details of one recalled - don’t pay attention to everything in the same place

43
Q

What is the ‘zoom lens’ model of visual attention?

A

Attended region can grow or shrink depending on the size of the area to be processed (Eriksen and Yeh, 1985)

44
Q

What are the different types of visual search?

A

Feature search → Target defined by the presence of a single feature

Conjunction search → Target defined by the conjunction(co-occurrence) of two or more features

Spatial configuration search → The target and distractors contain the same basic features

45
Q

What is efficiency of visual search and how does it differ?

A

Efficiency of visual search is the average increase in RT for each item added to the display
Measured in terms of search slope of ms/item
Larger the search slop (more ms/item), the less efficient the search
Some searches are efficient and have small slopes
Some searchers are inefficient and have large slopes
More distractors = More inefficient
Faster to find the target than identifying that there is no target

46
Q

What is the binding problem?

A

he challenge of tying different attributes of visual stimuli, which are handled by different brain circuits, to the appropriate object so we perceive a unified object
E.g. a vertical red bar moving to the right

Colour, motion and orientation are represented by separate neurons
How do we combine these features when perceiving the bar?
Example of conjunction search with binding problem

47
Q

What is feature integration theory? (object based theory)

A

Treisman and Gelade (1980) - Theory of visual attention
Limited set of basic features can be processed in parallel preattentively but other properties (including correct binding of features to objects) require attention
Preattentive stage → Processing of a stimulus that occurs before selective attention is deployed to that stimulus

48
Q

Is there evidence features are represented independently of each other and need to be bound together?

A

Yes

Illusory conjunction → An erroneous combination of two features in a visual scene

E.g. Seeing a red X when the display contains red letters and Xs but no read Xs

Illusory conjunctions provide evidence that some features are represented independently and must be correctly bound together with attention

49
Q

What is top-down attention vs bottom-up attention?

A

Using own knowledge (top-down)

Someone else directing attention (bottom-up)

50
Q

What is covert visual attention?

A

Possible that objects can be attended to covertly (Poser, 1980)
Can process information to some extent even when our eyes are not directly focused on it
Looking out of the corner your eye
Such strategies are of limited relevance during purposeful action such as making a cup of tea/crossing the road (Land, 2009)

51
Q

What is overt visual attention?

A

When we inspect visual stimuli or scenes, what controls the movement of attention?
Is attention captured by stimuli/objects or do we intentionally deploy attention? - sense fixation bias
Is attention controlled by us or by the stimuli? - Attention is grabbed by what is salient
Top-down processes versus bottom-up processes

52
Q

What is the problem with saliency models (selecting information on the basis they are noticeable)?

A

Important information may not be salient - e.g. stop signs in a cluttered environment
Salient information may not be important
Doesn’t account for many observed fixations - especially in natural behaviour (Land)

53
Q

How is is top-down attention involved in the difference between picturing a scene and acting within a scene?

A

Place the image of the object of interest on the part of the retina with highest acuity (the fovea)

Keep image in eye stationary despite movement of the object or movements of ones head

54
Q

What did Yarbus (1967) find out about top-down processing?

A

The human eyes voluntarily fixate on those elements of a visual scene that carry essential and useful information

The more information is contained in an element, the longer the eyes stay on it

Yarbus (original experiments) - Saccadic eye movements reflect cognitive processes

The distribution of fixations on the elements of a scene changes depends on the purpose of the observer

People who think differently also, to some extent, see differently
Where we look drive by top down processes (e.g. certain goal to find something in an image)

55
Q

How can importance of a task influence eye tracking and behaviour?

A

In cases where the task structure is evidence = More easily interpreted as it provides external referent to internal computations
Eyes are positioned at the point which is not the most visually salient (most visually noticeable) but best for spatio-temporal demands of task
Fixations are tightly linked in time to evolution of the task

56
Q

How can importance of a task influence eye tracking and behaviour?

A

In cases where the task structure is evidence = More easily interpreted as it provides external referent to internal computations
Eyes are positioned at the point which is not the most visually salient (most visually noticeable) but best for spatio-temporal demands of task
Fixations are tightly linked in time to evolution of the task

57
Q

What did Land and MacLeod (2001) find out about eye movements being predictive?

A

Expert vs Novice cricketers - See if fixation on ball predicts move

Too fast for continuous smooth pursuit

Cognitive capabilities between people differ - so differences in gaze behaviour

Eye movements are predictive
Better batsmen fixate on the bounce point earlier
Shift eye movement attention (saccade)

Expert pick up information faster to make a decision on where to hit the ball compared to a novice
Novices less accurate

Saccades (rapid eye movement for orienting gaze) are often made to a location in a scene in advance of an expected event

Saccades were always preceded by a fixation on the ball as it left the bowler’s hand, showing that batsmen use current sensory data in combination with learnt models of the ball’s motion to predict the location of the bounce

Thus, eye movement patterns appear to be shaped by learnt internal models of the dynamic properties of the world.

58
Q

How can eye movements be driven by prospect of rewards?

A

Eye movements driven by prospect of reward
Cell responses reflect the reward of making a certain movement

The mental programs that drive gaze selection are increasingly seen to be reward-based

This direction is spurred by extensive neural recordings that show vast areas of the brain’s gaze computation system exhibit sensitivity to reward signals, as well as developments in reinforcement learning theory that make very specific predictions

59
Q

Why are eye movements predictive?

A

Photoreceptors
Ganglion Cells
LGN
Primary visual cortex
Other cortical brain areas
Mid-brain
Brain stem
Muscles
Round trip from eye to brain to muscles takes a minimum of 200 msec. Cricket ball only takes about 600 msec. Prediction gets around the problem of sensory delays

60
Q

What is representative design (Brunswik, 1956)? Evidence in visual search?

A

Organisms adapt to their natural environment, it is important that experimental stimuli are sampled from the organism’s natural environment

Visual search: Search for arbitrary objects is not very efficient

Scene-based guidance would help you find the tap in the next scene (picture of kitchen)

In real-world searches, real world guides visual search
Scene-based guidance → Information in our understanding of scenes that help us find specific objects in scenes

For instance, a mug or bowl is typically found on horizontal surface and a picture will typically be found on a vertical surface

61
Q

What is cognitive ethology? (Kingston et al., 2008)

A

Advocates the studying of behaviour under realistic conditions

Originally applied to study of animal behaviour

62
Q

What two incorrect assumptions do researchers conducting lab studies often make?

A

Processes that subserve cognition are invariant and regular across conditions (e.g. size-weight illusion)

Situational variability can be reduced or eliminated without affecting the nature of the process being measured

63
Q

What are examples of restrictions in lab studies?

A

2d
Limited resolution
Size of display
Unnatural responses
Constrained head movements

64
Q

What did Savelsbergh et al. (2005) and Dicks et al. (2010) show about the difference between simulated tasks and real-life tasks?

A

Savelsbergh et al. (2005)
investigated gaze behaviour of goalkeepers during a video simulation of a penalty kick
They incorrectly assumed that the behaviours observed during the simulation were invariant and therefore representative of real-world behaviour

Dicks et al. (2010) replicated Savelsbergh et al.’s (2005) study but with the inclusion of a real-world condition
Dicks et al. (2010) observed similar behaviour in the simulation condition to that reported by Savelsbergh et al. (2005).
The simulated condition created an artificially high percentage of fixations towards the legs of the penalty taker whereas in the real world the goalkeepers fixated almost exclusively on the ball.

Psychology 2B (5 decks)

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