Chapter 3 - Visual Perception

Question 1

Perception

Answer 1

The set of processes by which we recognize, organize, and make sense of the sensations we receive from environmental stimuli.

Question 2

Gibson’s framework of perception (DIPP)

Answer 2

Distal object - the object in the external world
Informational medium
Proximal stimulation - of the appropriate sensory modality
Perceptual object - what you see, resembling the distal object.

Question 3

Ganzfeld

Answer 3

A uniform field of stimulation - “complete field”.

Question 4

Percept

Answer 4

A mental representation of a stimulus that is perceived.

Question 5

The what-where hypothesis

Answer 5

Two pathways from V1:
The dorsal pathway = where pathway, responsible for processing location and motion information.
The ventral pathway = what pathway, responsible for processing color, shape, and identity.

Question 6

The what-how hypothesis

Answer 6

Two pathways from V1:
The dorsal pathway = how pathway, responsible for controlling movement in relation to objects
The ventral pathway = what pathway, responsible for processing color, shape, and identity.
This is the best supported hypothesis.

Question 7

Bottom-up theories

Answer 7

Perception starts with the stimuli and lead to higher level processes. Data-driven theories.

Question 8

Top-down theories

Answer 8

Perception is driven by high level cognitive processes, existing knowledge, and prior expectations. Perception is constructive, it affects and is affected by the world as we experience it. According to constructivists, during perception, we quickly form and test various hypotheses regarding percepts, based on what we sense (sensory data), what we know (stored in our memory), and what we can infer (using high-level cognitive processes). Examples that support the constructive theory include color constancy and perceptual constancy.

Question 9

Gibson’s theory of direct perception

Answer 9

Sometimes called ecological perception, this theory proposes that the information provided by the environment, in our sensory receptors, is all we need to perceive anything. We use texture cues to perceive depth and distance. We are biologically tuned to respond to stimuli, and no higher processes are needed to make sense of it. Interested in perception in daily life, not the lab. This theory is partly supported by the existence of mirror neurons, and how infants quickly develop perceptual awareness without prior experience.

Question 10

Sensory adaptation

Answer 10

Receptor cells adapt to constant stimulation by not firing until there is a change in stimulation. Thus, variation is necessary for perception to work.

Question 11

Template theories

Answer 11

These theories claim that our minds store many sets of templates - highly detailed models (chunks of information) for patterns we might recognize. We recognize patterns by comparing them to our set of templates.
Expertise is attained by acquiring chunks of knowledge in long-term memory that can later be accessed for fast recognition. Does not explain recognition of letters across fonts and handwriting styles.

Question 12

Feature-matching theories

Answer 12

These theories claims that we attempt to match features of a pattern to features stored in memory, rather than to match a whole pattern to a template or a prototype.

Question 13

Selfridge’s pandemonium model

Answer 13

A type of feature-matching theory: four kinds of demons receive and analyze the features of a stimulus: image demons, feature demons, cognitive demons, and decision demons. The image demons receive sensory input, and pass it on to the feature demons. The feature demons calls out when matches are made between the stimulus and the given feature, and sends this info to the cognitive demons. The cognitive demons shout out possible patterns stored in memory that conform to one or more of the features noticed by the feature demons. Finally, a decision demon listens to the cognitive demons. It decides what has been seen, based on which cognitive demon is shouting most frequently/loudly/has the most matching features.

Question 14

Biederman’s Recognition-by-Components Theory

Answer 14

We quickly recognize objects by observing the edges of them and then decomposing the objects into geons (geometrical shapes like cylinders and cones). The geons are viewpoint-invariant, and thus the objects constructed from geons are recognized easily from many perspectives, despite visual noise. According to Biederman, this theory explains how we recognize the general classification for objects quickly, automatically and accurately. The RBC theory fails to explain how we recognize particular instances of objects.

Question 15

Context effects

Answer 15

Influences of the surrounding environment on perception.

Question 16

Configural superiority

Answer 16

Objects presented in certain configurations are easier to recognize than the objects presented in isolation, even if the objects in the configurations are more complex than those in isolation.

Question 17

Viewer-centered perception

Answer 17

The individual stores the way the object looks to them - what matters is the appearance of the object to the viewer, not the actual structure of the object.

Question 18

Object-centered perception

Answer 18

The individual stores a representation of the object, independent of its appearance to the viewer - the shape of the object will stay stable across different orientations.

Question 19

Gestalt approach to form perception

Answer 19

The whole differs from, and is more than, the sum of its individual parts. The overarching law of the Gestalt approach is the law of Prägnanz. We prefer coherent forms. Gestalt principles include figure-ground perception, proximity, similarity, continuity, closure, and symmetry.

Question 20

Landmark-centered perception

Answer 20

Information is characterized by its relation to a well-known or prominent item.

Question 21

Two systems for recognizing patterns (Farah)

Answer 21

The first system (feature analysis system) specializes in recognizing parts of objects and in assembling those parts into distinctive wholes.
The second system (configurational system) specializes in recognizing larger configurations and not analyzing the parts, and is most relevant to recognizing faces.

Question 22

Prosopagnosia

Answer 22

The inability to recognize faces.

Question 23

Perceptual constancy

Answer 23

When our perception of an object remains the same even when our proximal sensation of the distal object changes. Two of the main constant factors are size and shape.

Question 24

Size constancy

Answer 24

The perception that an object maintains the same size despite changes in the size of the proximal stimulus.

Question 25

Shape constancy

Answer 25

The perception that an object maintains the same shape despite changes in the shape of the proximal stimulus.

Question 26

Monocular depth cues

Answer 26

Can be seen with one eye. Texture gradients, relative size, interposition, linear perspective, aerial perspective, and motion parallax are monocular depth cues.

Question 27

Binocular depth cues

Answer 27

Needs both eyes to see. Convergence and disparity are binocular depth cues.

Question 28

Agnosia

Answer 28

Trouble perceiving sensory information, often caused by damage to the border of the temporal and occipital lobes or restricted oxygen flow to the brain. Generally, people with agnosia have normal sensations of what is in front of them, but they cannot recognize what the object is - they have trouble with the what pathway.

Question 29

Simultagnosia

Answer 29

Inability to pay attention to more than one object at a time.

Question 30

Optic ataxia

Answer 30

An impaired ability to use the visual system to guide movement, trouble reaching for things - they have trouble with the how pathway.