Week Five/Six: Sensation & Perception

Question 1

SACCADE

Answer 1

Rapid movements of the eye between fixation points (A ballistic movement from figure to figure in a display or scene.)

Therefore it can be maintained that eye movements are not fluid/uninterrupted/flowing rather they are ballistic.

Question 2

What is the gist of a scene?

Answer 2

the basic storyline of a scene or an image. Muddled or nebulous explications of what is presented in a short period of time.

E.g., Only recalling silhouettes or contours rather than precise detail.

Question 3

What are the functions of motion perception?

Answer 3

Motion perception can help break camouflage, help attract attention, help segregate objects from the background, help interpret events, and help determine the structure of objects and/or actions that people are performing.

Question 4

Kinetic depth effect

Answer 4

Motion allow us to infer structure.

Motion can help us determine the shape of an object.

Question 5

Akinetopsia

Answer 5

Impaired ability to perceive motion

Question 6

Apparent Motion

Answer 6

Two static images in succession belie movement

Question 7

Apparent Motion caveats

Answer 7

Insensitive to colour changes and distance. Colour can also be used to disambiguate motion.

Question 8

Motion Aftereffect

Answer 8

A result of up and down cells in the eyes that cancel each other out, producing the effect of upward motion.

Cells innervated during downward motions become fatigued

Question 9

Induced motion

Answer 9

A nearer object (usually a larger one) either affects the perceived motion of a second object (usually a smaller one) or causes a second object to appear to move.

Question 10

When DO we perceive motion?

Answer 10

Real Motion, illusory motion (static image visual illusion), induced motion, and motion aftereffects.

Question 11

Motion illusions

Answer 11

Motion illusions can inform us of the processes underlying motion perception

Question 12

Aperture problem

Answer 12

When a movement of an object is obscured, (therefore only seen through an aperture - an opening, gap, or hole), the perception of the movement will be inaccurate.

Motion percept captures only what is visible and therefore reflects the orientation of the aperture.

E.g., Barbel pole illusion (Rotating cylinder but it appears to be moving vertically/upward.)

Question 13

Describe the Suchow & Alvarez (2011) experiment

Answer 13

It was a demonstration of induced change blindness. Where colour changes belie (ostensibly display) movement. And movement truncates the rate and frequency of perceived colour changes

Question 14

Footsteps Illusion Anstis (2003)

Answer 14

Reduced contrast appear to move slower

Question 15

Functions of colour perception

Answer 15

(1) Animals often use colour to attract mates

(2) As a warning, to deter or repel

(3) It is proposed that colour vision evolved to help search for things.

(4) Huberman asserts that coloured vision evolved for temporal perception through discerning hues of colour in the sky.

Question 16

Why are venomous organisms colourful?

Answer 16

Venom production requires a lot of energy. Colour acts as a deterrent in nature.

Question 17

Munsell Colour System

Answer 17

Munsell colour system colours are categorized according to value (lightness), hue (colour) and chroma (saturation)

Question 18

Trichromatic Theory of vision

Answer 18

Three types of cones that respond maximally to three different wavelengths.

S Cones: Blue
Rod: Black
M Cone: Green
L Cone: Red

Question 19

Colour matching

Answer 19

“It follows that if a patch of light were to activate the S, M, and L cones to the same extent it would look identical to the test field.”

Question 20

What are metamers

Answer 20

Physically different stimuli that appear the same.

Question 21

Trichromats

Answer 21

Three cone types

Question 22

Monochromatism

Answer 22

Have no functioning cones. Those affected only see the world in shades of grey because of the excessive saturation of their cones.

Question 23

There are three types of colour deficiency. Namely …

Answer 23

Protanopia = L Cone Absent
Deuteranopia = M Cone Absent
Tritanopia = S Cone Absent

Question 24

Dichromats lack one cone type.

Question 25

Unilateral dichromacy

Answer 25

Colour deficiency only affecting one eye

Question 26

Opponent-Process Theory of Colour vision

Answer 26

Blue and yellow, red and green are opponent colours.

Question 27

Afterimages

Answer 27

Upon habituating on a display consisting of four segments/quarters of red, blue, green, and yellow. The cones in our eyes continue to fire momentarily when a white transition is introduced.

Question 28

Discounting the illuminant

Question 29

What are voluntary fixations (attention) determined by?

Answer 29

Voluntary fixations are determined by goals and expectations

Question 30

What actuates our involuntary process (that is mediated by attentional capture) in first directing our attention?

Answer 30

Region of luminance/colour contrast
Region of flicker/motion contrast
Region of size contrast
Region of orientation contrast

Question 31

What are fixation durations and repetition determined by? These attract our attention longer and more often.

Answer 31

Semantic inconsistency (If an item belongs in a particular place/context.)

Syntactic inconsistency (If an item that belongs in a particular place is not adhering to natural laws or performing its respective role e.g., a pot that is hovering over a stove. It is semantically consistent, but by normative standards, syntactically inconsistent.)

Vo & Henderson (2009).

Question 32

Attention has three main effects. What are they?

Answer 32

Attention accelerates our responses (Think about a boxer in a ring, if he attends to his opponent he is more vigilant and therefore prone to respond quicker and execute the appropriate moves accordingly.)

Attention can change the apparent contrast of an object. Make an object (a targeted visual icon) more vivid.

Attention can influence physiological responses.

Question 33

What is the binding problem?

Answer 33

The issue of how an object’s features are combined (ie. bound) to create a coherent percept is known as the binding problem.

Question 34

What is an illusory conjunction?

Answer 34

Feature Integration Theory predicts that features from different objects will be incorrectly bound together if attention is inhibited.

Treisman & Schmidt (1982) showed that such illusory conjunctions occur

They presented character strings very briefly (95-168 ms) followed by a noise mask

The primary task was to report the two numbers.

Then O’s (i.e. observers) were asked to report the coloured letters.

O’s often associated the wrong colour with the wrong letter.

Such incorrect bindings are known as illusory conjunctions.

Question 35

Why does Feature Integration Theory predict conjunction searches to be slow?

Answer 35

Some forms of visual search require binding to occur.

For example, binding is required if the target contains the same features as the distractors. If the target differs from the distractors only by its particular conjunction of features then that is a conjunction search.

FIT predicts that attention needs to be applied to each object in turn (i.e., one at a time) to determine whether or not the attended object is the target.

Thus, these searches are predicted to be very slow.

Question 36

Why can you not have reddish green?

Answer 36

Red and green are opponent colours.

As described from the perspective of the visual system, we have subsequent stages of processing where we analyse colours on how black/white or red/green or blue/yellow they are.

Therefore having to decide how red or green colour lends itself to why they cannot be conflated.

Red and green forms YELLOW

Question 37

What colour is the afterimage of a blue object?

Answer 37

A evanescent yellow colour.

Question 38

What factors determine the colour of reflected light?

Answer 38

The colour of light reflected by an object is determined by the object’s reflectance and illumination

Question 39

How does the visual system achieve colour constancy?

Answer 39

Via two ways … habituation and discounting the illuminant (The brain can figure out that an object is illuminated by red light, subconsciously we can ascertain the colour of the object by eliminating the colour that is being reflected)

Question 40

What is the relationship between depth and size

Answer 40

Depth and size are closely related. How big an object appears can affect how far away it appears and how far away an object appears can affect how BIG it appears (So vice versa.)

“How big an object appears can affect how far away it appears. How far away an object appears can affect how big it appears.”

Question 41

Oculomotor cue definition

Answer 41

Cues related or referring to the eye motor system. Knowing the orientation of the eyeball in space, as well as thickness of the lenses.

Question 42

There are two oculomotor cues, what are they?

Answer 42

Binocular Convergence and accommodation

Binocular Convergence occurs when fixating upon an object. When an object is nearer, our eyes CONVERGE whereas when an object is further away, our eyes DIVERGE.

Question 43

Accomodation

Answer 43

Changing the focal length of the lens by expansion and contraction.

The further an object is, the more the eyes contracts hence producing a thinner lens, whereas the nearer an object is the more the eyes expand (Larger visual aperture).

Question 44

What are monocular cues and what the three main monocular cues?

Answer 44

Accomodation, Pictorial cues, and movement-based cues

Question 44

What are monocular cues and what the three main monocular cues?

Answer 44

Accomodation, Pictorial cues, and movement-based cues

Question 45

Accomodation

Question 46

Pictorial Cues

Answer 46

7 types: occlusion, relative height, familiar and relative size, perspective convergence, atmospheric perspective, texture gradient, shadows

Question 47

Occlusion (1st pictorial cue)

Answer 47

Occlusion is a cue for DEPTH. We can see objects behind or in front of one another in an order or arrangement. If an object is occluded by another, we know that it is further away.

“Estimating the distance of an object relative to a closer object by their relative height (to the nearest object.)”

(A process whereby something is hidden or obscured from PROMINENCE or view.)