Chapter 3

Question 1

What is the difference between sensation and perception?

Answer 1

Sensation-stimulation of sensory receptors (ex: light–eye, sound waves–ear)
Perception- Organizing sensory input and giving it meaning. Qualitative experience of sensation (recognizing a face/melody)

Question 2

What is visual agnosia?

Answer 2

The inability to recognize objects visually-can identify using other senses (touch)

Question 3

What is prosopagnosia?

Answer 3

Patients are unable to recognize faces, including those of family, friends, themselves etc. Can recognize other objects fine.

Question 4

What is the cornea?

Answer 4

Protective bump at the front of the eye, mainly responsible for focusing power (80%). Sharply refracts (bends) light.

Question 5

What is the pupil?

Answer 5

A hole in the iris that allows light into the eye. Our eyes try to keep that amount optimal (pupillary reflex). Dilation or constriction is controlled by muscles in the iris.

Question 6

What is the lens?

Answer 6

Elastic, crystalline structure that also focuses light onto retina (20%). Purpose is to focus light directly onto retina

Question 7

What is accomondation?

Answer 7

When the lens changes shape to focus light directly.

Question 8

What happens when the lens is thicker vs thinner?

Answer 8

Thicker-Focuses nearby objects (light bends more), ciliary muscles are contracted
Thinner-Focuses distant objects (light bent only a bit). Ciliary muscles are relaxed

Question 9

Why is our image of the world inverted?

Answer 9

Because refraction by the lens brings all the light rays reflected by a specific point on the object into focus at the corresponding point on the retina.

Question 10

What is myopia (nearsightedness?)

Answer 10

Light from distant sources is focused in front of the retina due to slight elongation of the eye.

Question 11

What is hyperopia (farsightedness)

Answer 11

Light from nearby sources is focused behind the retina due to slight shortening of the eye.

Question 12

What is astigmatism?

Answer 12

Lens or cornea is irregularly shaped resulting in more than one focal point. Some of the image is focused in front of the retina, behind the retina, and some in front.

Question 13

What are the 5 cells of the retina?

Answer 13

1. Photoreceptors (rods/cones)
2. Horizontal cells
3. Bipolar cells
4. Amacrine Cells
5. Ganglion Cells

Question 14

What is the fovea?

Answer 14

Small (1mm^2) area located in the centre of retina-involved in directed looking. Highest density of photoreceptors, great visual acuity, only cones, each connecting to one bipolar and one ganglion cell.

Question 15

What is the blind spot?

Answer 15

Where the optic nerve leaves the eye at the back of the retina- we are normally not aware of it as the brain fills in this missing information.

Question 16

What is bottom-up perception?

Answer 16

Basic sensory elements are combined, combinations are combined, eventually produce a perception of the ‘whole’.

Question 17

What are the steps of bottom-up perception?

Answer 17

Photoreceptors fire in given pattern (sensation)—-> Detect specific features—-> Combine features into more complex forms—->Recognize stimulus (low to high level)

Question 18

What is the visual pathway to the brain?

Answer 18

Optic nerve, lateral geniculate nucleus (thalamus), primary visual cortex

Question 19

What is topographic organization?

Answer 19

Adjacent retinal cells activate adjacent cortical cells. Like a “map” of the visual scene.

Question 20

What is cortical magnification?

Answer 20

Maps are distorted (think homunculi) because much of the visual cortex is dedicated to fovea (whatever you’re looking at directly has as larger amount of cortex dedicated to it)

Question 21

What are feature detector cells?

Answer 21

Cells that fire for specific features based on patterns of ganglion’s firing.

Question 22

What is hierarchical processing?

Answer 22

Inputs from feature detectors are combined when certain objects with multiple features are seen. Creates combos of combos.

Question 23

What is parallel processing?

Answer 23

The eye detects things like colour, brightness and lines all simultaneously. They then get processed along their own track for awhile, and then get combined back into a single percept. (feature maps).

Question 24

What are the two pathways for the visual association cortex?

Answer 24

Dorsal-Action with object

Ventral-Object naming and perception

Question 25

What is serial processing?

Answer 25

Each feature gets processed one at a time. Used to be widely believed that this was how it worked, but not anymore.

Question 26

What is the theory of bottom-up perception and feature detecting?

Answer 26

Object recognition is all about recognizing patterns of specific features.

Question 27

What is the Pandemonium Model?

Answer 27

Model of letter recognition, basically says specific feature detectors are like a bunch of rowdy shouting/listening demons.

Question 28

What are the 4 types of demons?

Answer 28

Image demon, feature demons, cognitive demons, and decision demon

Question 29

What is the Recognition by Components model and who coined the term?

Answer 29

A way of explaining how we detect very complex stimuli-explains why there aren’t a billion feature detectors. Basically states that the world is made up of 36 geons and all objects have a unique configuration of these geons. Irving Biederman came up with this theory

Question 30

What is the Principle of Componential Recovery?

Answer 30

As long as we can perceive the relative size/placement of a few of the geons of an object, we can recognize it!

Question 31

What is one of the problems with bottom-up perception?

Answer 31

The Inverse Projection Problem-The task of determining an object that caused a specific firing pattern on the retina-how do we detect shadows that could be hundreds of different objects? Impossible to solve using only bottom-up perception

Question 32

What was Stephen Palmer’s experiment?

Answer 32

Asked participants to name line drawn objects. BEFORE he showed them the objects, he showed them a scene, but said that the scene didn’t matter. The scene was appropriate/inappropriate for the certain object. Ex) A kitchen=bread vs a music room and bread. There were also two types of inappropriate objects (look similar to appropriate one ex: bread and mailbox. Look different from appropriate one ex: Bread and drum).

Question 33

What were the results of Palmer’s experiment?

Answer 33

Performance was better when object presented after seeing the appropriate context. (80% vs 40%). More accurate and faster identification of the object. If object was presented briefly, people often mistake the incorrect but similar object for the correct object.

Question 34

What is priming?

Answer 34

When our prior knowledge, experience prepares the system to see certain objects so we recognize them better Ex) Recognizing a hand makes it much more likely that the thing on their wrist is a watch or a bracelet

Question 35

What is top-down perception?

Answer 35

Existing ideas, knowledge, or expectations about the “whole” affect how we interpret sensory stimuli.

Question 36

What are the steps of top-down perception?

Answer 36

Formulate perceptual hypothesis—-Examine features to check hypothesis—-Recognize stimulus.

Question 37

What are the 3 parts of top-down perception?

Answer 37

1) Organization/structure
2) Context
3) Attention

Question 38

What does organization/structure include?

Answer 38

Gestalt Laws-the whole is greater than the sum of it’s parts-real world tends to be relatively predictable, so our perceptions will often reflect this. What we perceive is based on what usually happens in the environment.

Question 39

What was Hermann von Helmholtz theory?

Answer 39

Theory of Unconscious Inference-explains how we decide among possibilities. Demonstrates the likelihood principle, we perceive the object that’s most likely to have resulted in that pattern of retinal stimulation.

Question 40

What is the Law of Continuity?

Answer 40

Points that, when linked together, would make a straight or smoothly curved continous line, belong together.

Question 41

What is the Law of Similarity?

Answer 41

Similar things tend to be grouped together.

Question 42

What is the Law of Proximity?

Answer 42

Elements that are near one another tend to be perceived as going together.

Question 43

What is the Law of Closure?

Answer 43

Tend to close in edges or fill in gaps of an incomplete figure to make a complete picture.

Question 44

What is the Law of Figure vs Ground?

Answer 44

Tend to perceive figures in the foreground on top of a (continuous) background. (optical illusion where you see two faces or a vase)

Question 45

What is the Law of Meaningfulness or Familiarity?

Answer 45

Tend to perceive things in terms of meaningful or familiar groupings.

Question 46

What is the Principle of Pragnaz?

Answer 46

Veryyy similar to Helmholtz. Tendency to perceive things such that the resulting structure is as simple as possible.

Question 47

What is the oblique effect?

Answer 47

People are more accurate in estimating and perceiving vertical/horizontal lines-best at vertical, because they are more common in the physical world!

Question 48

What is the light-from-above assumption?

Answer 48

We generally perceive indentations and protrusions by assuming that light is hitting them from above. (because light typically coms from above in our world)

Question 49

What are semantics and how do they affect perception?

Answer 49

Refers to meaning or knowledge. Affects our perception by assigning meaning of a scene or object in relation to what it does , where it’s used, and what happens there. Example is the Palmer Experiment (scene schema)

Question 50

What is schema?

Answer 50

A pattern of thought or behaviour that organizes or categorizes info into relationships

Question 51

How does context affect our perception?

Answer 51

The context in which we see something guides how we will perceive it, we form expectations

Question 52

What is the jumbled word effect?

Answer 52

Ability to read words in sentences despite the middle letters being mixed up

Question 53

What is a perceptual set?

Answer 53

Readiness to perceive things in a certain way ex) Harold Kelly’s guest lecturer.

Question 54

What are perceptual constancies?

Answer 54

Tendency to experience the same, stable perception despite changes in sensory input. If this didn’t happen, we’d have to rediscover what something is when presented in different lighting, distance, etc. Includes size constancy, lighting constancy, colour constancy, melodic constancy.

Question 55

What is size constancy?

Answer 55

Size of an object is not determined solely by the size of the image on the receptors. Size of an object is perceived as constant even across different distances.

Question 56

What is lightness constancy?

Answer 56

Object lightness is not determined solely by the amount of light reflected from it’s surface.

Question 57

What kinds of things best grab our attention?

Answer 57

Things of evolutionary importance-sexual items or things that make us feel fear.

Question 58

What are heuristics?

Answer 58

Often used in top-down perception; rule of thumb that often works to solve a problem (but not always)

Question 59

Is there one sure correct way of perceiving?

Answer 59

no! Bottom up and top down often work together.

Question 60

How does visual info travel through the brain?

Answer 60

Primary visual cortext—> parietal and temporal lobes

Question 61

What was Ungerleider and Mishkin’s experiment?

Answer 61

Ablated monkeys were given 2 different tasks: Object discrimination task (shown 1 object, then shown a second and asked to find the original object.
Landmark discrimination-Monkeys were given a tray with two foodwells. One was behind a cylinder. If they chose the one behind the cylinder, they were rewarded and quickly learned to choose that one.

Question 62

What were the results of Ungerleider and Mishkin’s study?

Answer 62

Temporal Ablation-monkeys couldn’t do object discrimination (ventral=what)
Parietal Ablation-Monkey’s can’t do landmark descrimination. (dorsal=where)

Question 63

What did Mel Goodale demonstrate with Patient DF?

Answer 63

Object recognition versus orientation versus action. Patient DF has poor object recognition and orientation, however her action with the object is unaffected!