Chapter 4 - Perception

Question 1

What are the two stages of perception?

Answer 1

Sensation, conversion of physical properties into neural code using the PNS in sensory neurons using transduction (physical stim to neural code).

Perception is the processing and interpretation of the sensory information into a form for behavioural decisions.

Question 2

What is it called when we use our senses to determine and interpret properties of our external environment?

Answer 2

Exteroception.

Question 3

What are the five senses (and their fancy names)?

Answer 3

Vision - Seeing
Olfaction - Smelling
Gustation - Taste
Audition - Hearing
Touch

Question 4

What are the senses that measure properties of our own body and what are they called?

Answer 4

Proprioception, determining location of our limbs.
Equilibrioception, determining balance.
Nociception, sense of pain due to bodily damage.

Question 5

What are the four broad classes of sensory receptors?

Answer 5

1. Chemoreceptors
   Detecting concentrations of chemicals in local environment from the nose or mouth. Can measure buildup of chemicals which may contribute to nociception.
2. Mechanoreceptors
   Stimulated by physical force detecting pressure and the inner ear for air vibrations, and arteries for blood pressure.
3. Thermoreceptors
   Stimulated by heat or cold in skin and internal organs.
4. Photoreceptors
   Responses modified by light as increased light energy results in lower neurotransmitters being released.

Question 6

What is the passage of light?

Answer 6

Cornea (through pupil of iris), retina (cones, rods), then optic nerve. Retinal cones concentrated in the fovea.

Question 7

What’s the difference of rods and cones?

Answer 7

Rods are distributed throughout the retina, useful in detecting light. Low-resolution. Periphery.

Cones are concentrated mainly in the fovea, useful for detecting colour. High resolution.

Question 8

What are visual agnosias?

Answer 8

When a person has difficulty recognizing or perceiving one kind of visual stimulus while maintaining the ability to process other kinds of stimuli.

Question 9

What is prosopagnosia?

Answer 9

Difficulty in recognizing individual faces, but can recognize objects and recall names and facts of people.

Question 10

What is semantic agnosia?

Answer 10

When someone can recognize faces, but not everyday objects and tools.

Question 11

If someone retains damage to the fusiform face area (FFA), what kind of visual agnosia may they have?

Answer 11

Propagnosia.

Question 12

If someone retains damage to the LOC (lateral occipital cortex), what visual agnosia may they have?

Answer 12

Semantic agnosia.

Question 13

What is the FFA responsible for?

Answer 13

It shows greater activity in facial recognition.

Question 14

What is the LOC responsible for?

Answer 14

Selectively activated when people do tasks of object recognition.

Question 15

What did the Greeble (Gauther and Taar) experiment find?

Answer 15

That the FFA was not specialized for faces but visual expertise.

Question 16

To what directions do axons diverge once visual input reaches the visual cortex?

Answer 16

The dorsal (where) to the parietal lobe and ventral (what) to the temporal lobe. Visual streams.

Question 17

What did Goodale and Milner conclude about the dorsal and ventral streams?

Answer 17

That the dorsal stream was more relative of action whereas the ventral stream was more relative of perception.

Question 18

Why is our ear filled with fluid?

Answer 18

Sound loses amplitude when it moves from air to fluid. The purpose of the ear structure (Pinna, ear canal, eardrum, ossicles, cochlea, basilar membrane) is to amplify sound so original frequencies are preserved in the cochlea.

Question 19

What is the organization of hair cells in the basilar membrane?

Answer 19

Coil shape in the cochlea. The further you go along the coil, the frequency of which the hair cells respond gets lower. High frequency at the start, lower frequency inner.

Question 20

What is the function of the dorsal and ventral stream when it comes to sound identification?

Answer 20

Dorsal - Localization
Ventral - Identification

Question 21

What are the two main properties of sound waves?

Answer 21

Frequency/wavelength, and amplitude.

Question 22

How does the olfactory system work?

Answer 22

Nostrils/throat -> olfactory epithelium (in the nasal cavity, strip of tissue). Senses transduce chemical information and move to the olfactory bulb.

Question 23

What are the two neural pathways found in rats that are activated when eating pleasurable food?

Answer 23

One to activation of pleasure centres manifested with liking or disliking behaviours.

One to activation of centres which make you WANT the food later on. (Operant)

Question 24

What is the constructive perception model?

Answer 24

The perspective that the perceptual processing is your brain attempting to construct a mental model of the external world based on sensory input.

Question 25

Where are nerve endings related to mechanoreceptors connected to?

Answer 25

The somatosensory cortex, and the cortical homunculus in which locations on this are respond to different regions of the body.

Question 26

What is unconscious interference?

Answer 26

Behavioural decisions based on the inferred model than on the sensory stimulus itself. My eye sees light patterns while my brain sees an image. My ear feels vibrations in the air while I hear music.

Question 27

What is Helmholtz’ idea of how we perceive the world?

Answer 27

That we use sensory information to create a mental model of the world around us. We take unstable and divided sensory input and unite it into an Idea of our environment. Symbolic representation.

Question 28

What is the Gibsonian/direct perception viewpoint?

Answer 28

That perception is direct and based directly on sensory stimulus and a person’s actions. Certain properties of sensory stimulus will guide that person in a continuous perception and action loop.

Question 29

According to the constructive or direct models of perception, how would I walk towards a target?

Answer 29

Constructively, your brain infers the location of the target in three dimensional space, and correspond by moving in that space to reach the target. Directly, you move your body in a way where the image of the desk is in the centre of our view constantly, and our motions are updated to reflect that.

Question 30

What is occlusion?

Answer 30

A process where something may be hidden or obscured by view.

Question 31

What is bi-stable stimuli?

Answer 31

A class of stimuli in which our brains can have a changing perspective on depending on which point you see it in.

Question 32

What is bottom-up processing?

Answer 32

Processing that does not require knowledge of the stimulus. Reaction without mental contemplation. Reaction-first. Brain later.

Question 33

What is top-down processing?

Answer 33

Where we leverage information gained prior that are not in the present stimulus itself in order to process it. Brain-first. Reaction later.

Question 34

What is the phoenemic restoration effect?

Answer 34

Where the brain “fills in” missing sounds from a speech signal based on expectation about which sounds belong in that portion.

Question 35

What is the issue of image segmentation?

Answer 35

That when we are presented with a whole image, we want to find which parts of the image start or end and categorize what region an image is taking up, or what something can be categorized as.

Question 36

What is figure-ground assessment?

Answer 36

Assigning the boundary from one side or the other, determining which regions of an object in a picture contain the objects and which regions are the continuous background.

Question 37

What is convexity?

Answer 37

The general bias to assign figure or ground such that the assigned figure has shape in which more of the contour is protruding outward.

Question 38

What is symmetry in Gestalt principles?

Answer 38

The tendency to assign figure or ground such that the resulting figure has bilateral mirror symmetry.

Question 39

What are the gestalt principles of image segmentation?

Answer 39

Biases in which we determine image segmentation. Symmetry Convexity Smaller region

Question 40

What are the gestalt principles of visual grouping?

Answer 40

Similarity Proximity Good continuation

Question 41

What is motion parallax?

Answer 41

The image of objects further away change their position slower than images closer to us.

Question 42

What is binocular disparity?

Answer 42

The different features of the image on our retina that fall on each eye, because of the space between our eyes.

Question 43

What is the template model of recognition?

Answer 43

Matching an object to an image stored in memory.

Question 44

What is classification?

Answer 44

A type of recognition where we can recognize something as part of a category even if we have never encountered that due to recogniziong common patterns.

Question 45

What is a scene schema?

Answer 45

With contextual recognition how we can infer certain things even when concealed due to the context or environment around them. If letters are concealed in a sentence, we can infer what would have been in their places.

Question 46

What is stereopsis?

Answer 46

The brain using differences in binocular disparity to determine the depth of objects relative to fixation.

Question 47

What is identification?

Answer 47

Being able to identify the same object across different phases, angles, or variation.