Week 8: The Visual World

Question 1

Electromagnetic Energy

Answer 1

Pulses of energy waves that can carry info from place to place

Question 2

Wave-length

Answer 2

Distance between one wave peak ant the next wave peak

Question 3

Visible Spectrum

Answer 3

the part of the electromagnetic spectrum that our eyes can detect (only the range from about 400 to 700 billionths of a meter

Question 4

Cornea

Answer 4

A clear covering that protects the eye and begins to focus the incoming light

Question 5

Pupil

Answer 5

A small opening in the centre of the eye

Question 6

Iris

Answer 6

the coloured part of the eye that controls the size of the pupil by constricting or dilating in response to light intensity

Question 7

Lens

Answer 7

A structure that focuses the incoming light on the retina

Question 8

Retina

Answer 8

Cell layer in the back of the eye containing photoreceptors

Question 9

Visual accomodation

Answer 9

the process of changing the curvature of the lens to keep the light entering the eye focused on the retina

Question 10

Nearsighted

Answer 10

When the focus is in front of the retina

Question 11

Farsighted

Answer 11

When the focus is behind the retina

Question 12

Optic Nerve

Answer 12

A collection of millions of ganglion neurons that sends vast amounts of visual info via the thalamus, to the brain

Question 13

Rods

Answer 13

Photoreceptors of the retina sensitive to low levels of light; located around the fovea

Question 14

Cones

Answer 14

Photoreceptors of the retina sensitive to colour; located primarily in the fovea

Question 15

Fovea

Answer 15

the central point of the retina

Question 16

Blind spot

Answer 16

A hole in our vision that is created because there are no photoreceptor cells at the place where the optic nerve leaves the retina

Question 17

Feature Detector Neurons

Answer 17

Specialized neurons, locate din the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus

Question 18

Hue

Answer 18

The shade of a colour

Question 19

Trichromatic Colour Theory

Answer 19

The colour we see depends on the mix of the signals from the three types of cones

Question 20

Colour Blindness

Answer 20

The inability to detect green and/or red colours

Question 21

Opponent-process colour theory

Answer 21

Proposes that we analyze sensory info not in terms of three colours but rather in three sets of “opponent colours”: red-green, yellow-blue, and white-black

Question 22

Gestalt

Answer 22

A meaningfully organized whole

“the whole is the sum of its parts”

Question 23

Summary of Gestalt Principles of Form Perception

Answer 23

Figure and Ground - We structure input so that we always see a figure (image) against a ground (background).

Similarity - Stimuli that are similar to each other tend to be grouped together.

Proximity - We tend to group nearby figures together.

Continuity - We tend to perceive stimuli in smooth, continuous ways rather than in more discontinuous ways.

Closure - We tend to fill in gaps in an incomplete image to create a complete, whole object.

Question 24

Visual Cliff

Answer 24

A mechanism that gives the perception of a dangerous drop-off, in which infants can be safely tested for their perception of death

Question 25

Binocular Depth Cues

Answer 25

Messages from our bodies and the external environment that supply us with info about space and distance

Question 26

Convergence

Answer 26

The inward turning of our eyes that is required to focus on objects that are less than about 50 feet away from us

Question 27

Accommodation

Answer 27

Helps determine dpeth

Question 28

Monocular Depth Cues that Help us Judge Depth at a Distance

Answer 28

Position - We tend to see objects higher up in our field of vision as farther away.

Relative size - Assuming that the objects in a scene are the same size, smaller objects are perceived as farther away.

Linear perspective - Parallel lines appear to converge at a distance.

Light and shadow - The eye receives more reflected light from objects that are closer to us. Normally, light comes from above, so darker images are in shadow.

Interposition - When one object overlaps another object, we view it as closer.

Aerial Perspective - Objects that appear hazy, or that are covered with smog or dust, appear farther away.

Question 29

Beta Effect

Answer 29

Perception of motion that occurs when different images are presented next to each other in succession

Question 30

Phi phenomenon

Answer 30

we perceive a sensation of motion caused by the appearance disappearance of objects that are near each other

Question 31

Seeing - Key Take Aways

Answer 31

Vision is the process of detecting the electromagnetic energy that surrounds us. Only a small fraction of the electromagnetic spectrum is visible to humans.

The visual receptor cells on the retina detect shape, colour, motion, and depth.

Light enters the eye through the transparent cornea and passes through the pupil at the centre of the iris. The lens adjusts to focus the light on the retina, where it appears upside down and backward. Receptor cells on the retina are excited or inhibited by the light and send information to the visual cortex through the optic nerve.

The retina has two types of photoreceptor cells: rods, which detect brightness and respond to black and white, and cones, which respond to red, green, and blue. Colour blindness occurs when people lack function in the red- or green-sensitive cones.

Feature detector neurons in the visual cortex help us recognize objects, and some neurons respond selectively to faces and other body parts.

The Young-Helmholtz trichromatic colour theory proposes that colour perception is the result of the signals sent by the three types of cones, whereas the opponent-process colour theory proposes that we perceive colour as three sets of opponent colours: red-green, yellow-blue, and white-black.

The ability to perceive depth
occurs as the result of binocular and monocular depth cues.

Motion is perceived as a function of the size and brightness of objects. The beta effect and the phi phenomenon are examples of perceived motion.

Question 32

Unimodial

Answer 32

Of or pertaining to a single sensory modality

Question 33

Sensory Modalities

Answer 33

A type of sense; ex. vision/audition

Question 34

Multimodial

Answer 34

Of or pertaining to multiple sensory modalities

Question 35

Multimodal Perception

Answer 35

The effects that concurrent stimulation in more than one sensory modality has on the perception of events and objects in the world

Question 36

Integrated

Answer 36

Process by which the perceptual system combines info arising from more than one modality

Question 37

Superadditive effect of multisensory integration/multisensory enhancement

Answer 37

finding that repsonses to multimodal stimuli are typically greater than the sum o f the independent responses to each unimodal component if it were presented on its own

Question 38

Unimodal components

Answer 38

the parts of a stimulus relevant to one sensory modality at a time

Question 39

Principle of Inverse Effectiveness

Answer 39

The finding that, in general, for a multimodal stimulus, if the response to each unimodal component (On its own) is weak, then the opportunity for multisensory enhancement is very large; however if one component (by itself) is sufficient to evoke a strong response, then the effect on the response gained by simultaneously processing the other components of the stimulus will be relatively small

Question 40

Multisensory Convergence Zones

Answer 40

Regions in the brain that receive input from multiple unimodal areas processing different sensory modalities

Question 41

Receptive field

Answer 41

The portion of the world to which a neuron will respond if an appropriate stimulus is present there

Question 42

Crossmodal receptive fields

Answer 42

A receptive field that can be stimulated by a stimulus from more than one sensory modality

Question 43

Spatial principle of multisensory integration

Answer 43

the finding that the superadditive effects of multisensory integration are observed when the sources of stimulation are spaitally related to one another

Question 44

Unimodal cortex

Answer 44

a region of the brain devoted to the processing of info from a single sensory modality

Question 45

Primary auditory cortex

Answer 45

area of the cortex involve din processing auditory stimuli

Question 46

Multimodal phenomena

Answer 46

effects that concern the binding of inputs from multiple sensory modalities

Question 47

McGurk effect

Answer 47

An effect in which conflicting visual and auditory components of a speech stimulus result in an illusory perecpt

Question 48

Double flash illusion

Answer 48

false perception of two visual flashes when a single flash is accompanied by two auditory beeps

Question 49

The perception of collisions between two circles (called “balls”)

Answer 49

the tendency to perceive two circles as bouncing off each other if the moment of their contact is accompanied by an auditory stimulus

Question 50

Rubber hand illusion

Answer 50

the false perception of a fake hand as belonging to a perceiver, due to multimodal sensory info

Question 51

Crossmodal Phenomena

Answer 51

effects that concern the influence of the perception of one sensory modality on the perception of another

Question 52

Primary visual cortex

Answer 52

Area of the cortex involved in processing visual stimuli

Question 53

Crossmodal Stimuli

Answer 53

A stimulus with components in multiple sensory modalties that interact w each other

Question 54

Monacular Depth Cues

Answer 54

Depth cues that help us perceive depth using only one eye