sensation and perception

Question 1

define attention

Answer 1

the ability to preferentially process some parts of a stimulus at the expense of processing other stimuli

Question 2

what are the eye movements between fixations called

Answer 2

saccades

Question 3

what is attentional capture

Answer 3

how you first fixate on notable or important parts of a scene (scalience)

Question 4

what directs attnetion

Answer 4

initially salience, but then our expectations and goals

Question 5

what is the binding probelm

Answer 5

the issue of how an objects individual features, such as a colour and shape, are combined to create a coherent percept

Question 6

what does feature integration theory state

Answer 6

the binding problem is solved by attending to only one location in a scene at a time

Question 7

what is an illusory conjuction

Answer 7

where the features of 2 objects are incorrectly bound into one object

Question 8

what is Balint’s syndrome

Answer 8

a condition resulting from damage to the parietal lobe, leading to a difficulty in focussing attention on a single object

Question 9

what is a conjuction search

Answer 9

when the target object differs from its distractors only by its particular combination of features, not the individual features themselves - attention needs to be applied to each object in turn to determine whether the attended object is the target

Question 10

what is structuralism

Answer 10

a theory proposed by Edward Titchener, claiming that sensations and perceptions are distinguished, and that sensations bind to form perceptions

Question 11

what is gestaltism

Answer 11

the theory that conscious awareness can have characteristics not present in any of the elementary sensations (we can make stuff up)

Question 12

two pieces of evidence for gestaltism

Answer 12

apparent motion (where two stationary dots in different positions alternatively flashed appear to be moving) as the observers doesnt actually see the objects moving - they just perceive this. Illusory contours (contours seen in placed where there are actually no physical contours) as the observers fills in the gaps themselves

Question 13

what are 7 principles that govern grouping

Answer 13

good continuation (aligned contours are grouped), pragnaz (meaning “good figure”. Groupings occur to make the resultant figure as simple as possible). Similarity (the more similar objects are, the more likely to be grouped together). Proximity, (the closer objects are, the more likely they will be grouped). Common fate (things that are moving in the same way are grouped together). Common region (elements within the same region of space tend to group together). Uniform connectedness (connected regions with the same visual characteristics tend to group together)

Question 14

4 principles that allow the figure of a scene to be percieved)

Answer 14

if the object is in front of the rest of the image , at the bottom of the image, convex or recognisable (based on expectations of what we think something should look like)

Question 15

how much time must a scene be presented to get a gist of the scene

Answer 15

around 27ms. with 250 ms required for accurate perception

Question 16

what part of the brain is associated with perceiving motion

Answer 16

the medial temporal area

Question 17

what is akinetopsia

Answer 17

a condition, resulting from disease or trauma to the middle temporal lobe, causing difficulty perceiving motion

Question 18

what are motion aftereffects

Answer 18

our photoreceptors can habituate to an image of constant motion so that when this stops, we may continue to perceive some form of motion

Question 19

what is induced motion

Answer 19

when a moving background causes a stationary object to appear to move

Question 20

the aperture problem?

Answer 20

when a moving object is partially obscured (viewed through an aperture), this can change how its motion is perceived

Question 21

what is visible light

Answer 21

electromagnetic radiation with wavelengths between 400 and 700 nm

Question 22

what is the colour white

Answer 22

a mixture of all the wavelengths of the visible spectrum

Question 23

what are the 2 photoreceptors found on the retina

Answer 23

rods and cones

Question 24

difference between rods and cones

Answer 24

rods cannot distinguish between colours and are only active at low light levels, while cones are active in normal light conditions and can perceive between colours

Question 25

what are the 3 types of cones and what do they see

Answer 25

s cones (small) - blue, m cones (medium) - green and L cones (large) - red

Question 26

what happens when an optimal wavelength is received by a cone

Answer 26

it becomes "excited", and fires electrical signals called spikes up the optic nerve

Question 27

what are metamers

Answer 27

objects that are made up of physically different wavelengths but appear to have the same colour

Question 28

what is monochromatism

Answer 28

where a person has no functioning cones and therefore are truly colour blind (only able to see black and white). They are also very sensitive to light

Question 29

what is dichromatism

Answer 29

where a person is lacking one of the three types of cones

Question 30

what is unilateral dichromatism

Answer 30

where a person has normal trichromatic vision in one eye and dichromatic vision in the other

Question 31

if you were to mix red and green light what would you get

Answer 31

yellow

Question 32

if you were to mix blue and yellow light?

Answer 32

white light, as it is light that contains blue, red and green

Question 33

what do protanopes lack

Answer 33

l cones

Question 34

what do deuteranopes lack

Answer 34

m cones

Question 35

what do tritanopes lack

Answer 35

s cones

Question 36

what are the three colour opponent channels

Answer 36

red-green, yellow-blue and white-black

Question 37

evidence for colour opponent channels

Answer 37

afterimages - when viewing a stimulus of one colour, the opponent colour percept will be supressed, however, our cones will habituate to this constant colour and become less sensitive to the stimulus. Therefore when a white stimulus is then shown, the opponent cones will respond more strongly (as they have not habituated) and you will therefore perceive this colour) the fact that some colour combinations are impossible ( you cant perceive a redish green or a blueish yellow

Question 38

what is colour constancy

Answer 38

the fact that we can perceive the colour of an object, even if it is only being shown under one wavelength of light, and therefore reflecting this light. eg. a green sweater under red light will only reflect red light, but still appear green

Question 38

what is colour constancy

Answer 38

the fact that we can perceive the colour of an object, even if it is only being shown under one wavelength of light, and therefore reflecting this light. eg. a green sweater under red light will only reflect red light, but still appear green

Question 39

how is colour constancy acheived

Answer 39

if an entire scene is under one colour of light eg. red, we habituate to this colour so that everything will appear greener or bluer than it otherwise would. We can also discount the illuminant, meaning that our brain can lear to determine, for example, that an object in a yellow scene that appears grey must actually be blue.

Question 40

3 types of depth perception cues

Answer 40

oculormotor (the ability to sense the state and position of our eyes), monocular (one eye) and binocular (both eyes)

Question 41

what are the 2 main oculomotor cues

Answer 41

binocular convergence and accomodation

Question 42

what is binocular convergence

Answer 42

when an object is close, our eyes will converge to see it. The body can use the distance between the lines of sight of our eyes to determine the distance of the object.

Question 43

what is accomodation

Answer 43

our lens changes to look at objects of different distances. A thinner lends is better able to see objects far away while a thick lens is used for closer objects. Our brain use this change in lens shape to determine distance

Question 44

what are the 3 main monocular cues

Answer 44

pictorial, accomodation and motion based cues

Question 45

what are the 7 pictorial cues

Answer 45

occlusion (if something is behind another object than it must be further away), relative height (a subject that is higher up in a scene appears further away), relative size, perspective convergence (2 parallel lines that appear to be converging indicate that they are getting further away), atmospheric perspective (as an object gets further way, the intensity of colour fades and there is less contrast between light and dark colours) , texture gradient (closer objects appear more detailed) and shadows

Question 46

2 motion based cues (monocular)

Answer 46

deletion and accretion (when moving, objects will disappear behind others and then reappear, indicating that they are further away) and motion parallax (objects that are closer will appear to move faster than those that are further away)

Question 47

what is retinal disparity

Answer 47

a binocular cue, the relative position between 2 objects on the retinal image, and the difference between these in each eye

Question 48

what is the correspondence problem

Answer 48

if there are multiple identical objects in a scene, it can be hard to figure out which images in the left image should be associated with which images in the right - the correspondence problem

Question 49

what 2 factors determine the percieved size of an object

Answer 49

angular size (on the retina) and its perceived depth

Question 50

what did Holway and Boring investigate in 1941

Answer 50

they determined how depth cues influence size judgement. An observer would sit at the intersection of 2 corridors containing a circle at the end of each and with a range of provided depth cues (binocular disparity, motion parallax and shadows), were made to estimate the size of the object - there more depth cues, the more accurate their guesses

Question 51

what is the ames room

Answer 51

a room where the design of the back wall interferes with the observers depth perception, making it seem like a straight wall. Therefore when 2 people are standing in 2 different corners of the room, their distance from the observer, and therefore size, is perceived wrong.

Question 52

what does sound mean

Answer 52

can refer to both the physical phenomenon (pressure waves) and the perceptual phenomenon of actually hearing this sound

Question 53

what is a pure tone

Answer 53

when the change in air pressure occurs in the shape of a sine wave

Question 54

what causes a higher pitch (for pure tones)

Answer 54

a higher frequency of the wave

Question 55

what does hertz mean

Answer 55

the amount of oscillations (periods/repeats) per second

Question 56

what affects the loundness of a sound

Answer 56

amplitude of the waves

Question 57

what is amplitude measured in

Answer 57

decibels

Question 58

what is a complex tone

Answer 58

the addition of 2 or more pure tones to form a non-sine graph

Question 59

what is perceptual loudness measured in

Answer 59

phons

Question 60

what determines the pitch of a complex tone

Answer 60

the fundamental frequency (if a tone is composed of 3 tones, 200 400 and 600, the fundamental frequency is 200 as all the other frequencies are multiples of 200). Even if the fundamental tone itself is absent, the tone will sound like the fundamental frequency as all the other harmonics are multiples

Question 61

what is timbre

Answer 61

the difference between the sounds of 2 sounds at the same pitch (a piano and guitar playing the same note will sound different). This occurs because while they may play the same fundamental frequency, they will play different harmonics of this frequency

Question 62

what does it mean if 2 pitches have the same chroma

Answer 62

correspond to the same letter note - multiples of the same frequency

Question 63

what are sound wave forms that dont repeat called

Answer 63

aperiodic

Question 64

2 main dypes of auditory localisation cues

Answer 64

binaural (one ear) and monaural (both ears)

Question 65

2 binaural cues

Answer 65

inter-aural time difference (a sound coming from the left will reach the left ear first) and inter-aural level difference (a sound coming from the left will be louder in the left ear than the right)

Question 66

4 factors that determine the quality of architectural acoustics

Answer 66

reverberation time (the time it takes for a sound to decrease by 60 dB), intimacy time (the difference between when the direct sound arrives and the first indirect sound arrives), bass ratio (the ratio of low frequencies to middle/high frequencies) and spaciousness factor (the ratio of indirect sound to total sound)