Chapter 4- Perceiving and Recognizing Objects

Question 1

What are cells in VI interested in?

Answer 1

The cells in VI are optimally stimulated by bars and gratings of different orientations.

Question 2

Extrastriate Cortex

Answer 2

The region of cortex bordering the primary visual cortex and containing multiple areas involved in visual processing.

Question 3

Border Ownership

Answer 3

When one object is in front of another there will be a visual border formed between the object and the background. That border is “owned” by the object. It is the edge of the object, not a property of the background.

Question 4

What are the two main pathways from the extrastriate regions?

Answer 4

The two main pathways are the “what” and “where” pathways.

Question 5

What does the “where” pathway do?

Answer 5

This pathway heads up into the parietal lobe. Visual areas in this pathway seem to be important for processing information relating to the location of objects in space and actions required to interact with them.

Question 6

What does the “what” pathway do?

Answer 6

This pathway heads down into the temporal lobe and is known as the what pathway. This pathway appears to be the locus for the explicit acts of object recognition that are of particular importance in this chapter.

Question 7

Lesion

Answer 7

In reference to neurophysiology, 1. (n) A region of damaged brain. 2. (v) To destroy a section of the brain.

Question 8

Agnosia

Answer 8

A failure to recognize objects in spite of the ability to see them. Agnosia is typically due to brain damage.

Question 9

Inferotemporal (IT) Cortex

Answer 9

Part of the cerebral cortex in the lower portion of the temporal lobe, important in object recognition.

Question 10

What did they discover regarding cells in the IT cortex?

Answer 10

They discovered that they have receptive fields that could spread over half or more of the monkey’s field of view. Furthermore, the usual spots and lines didn’t work well at all, but the silhouette of a monkey hand worked fantastically for some cells.

Question 11

Homologous Regions

Answer 11

Brain regions that appear to have the same function in different species.

Question 12

Fusiform Face Area (FFA)

Answer 12

A region of extrastriate visual cortex in humans that is specifically and reliably activated by human faces.

Question 13

Extrastriate Body Area (EBA)

Answer 13

A region of extrastriate visual cortex in humans that is specifically and reliably activated by images of the body other thana the face.

Question 14

Parahippocampal Place Area (PPA)

Answer 14

A region of extrastriate visual cortex in humans that is specifically and reliably activated more by images of places than by other stimuli.

Question 15

Visual World Form Area (VWFA)

Answer 15

A region of extrastriate visual cortex in humans that is specifically and reliably activated more by images of written words than by other stimuli.

Question 16

Feedforward Process

Answer 16

A process that carries out a computation (e.g., object recognition) one neural step after another, without need for feedback from a later stage to an earlier stage.

Question 17

Reverse-Hierarchy Theory

Answer 17

A theory that fast, feedforward processes can give you crude information about objects and scenes based on activity in high-level parts of the visual cortex. You become aware of details when activity flows back down the hierarchy of visual areas to lower-level areas where the detailed information is preserved.

Question 18

Mid-Level (Or Middle) Vision

Answer 18

A loosely defined stage of visual processing that comes after basic features have been extracted from the image (low-level or early, vision) and before object recognition and scene understanding (high-level vision).

Question 19

What is the goal of mid-level vision?

Answer 19

The goal is to organize the elements of a visual scene into groups that we can then recognize as objects.

Question 20

Illusory Contours

Answer 20

A contour that is perceived even though nothing changes from one side of it to the other in an image.

Question 21

Occlusion

Answer 21

The fact that we can recognize that one object may be occluding, or blocking, another in a visual stimulus.

Question 22

Rules of Evidence

Answer 22

The tendency of the visual system to make inferential leaps.

Question 23

Structuralism

Answer 23

In reference to perception, a school of thought that believed that complex objects or perceptions could be understood by analysis of the components.

Question 24

Gestalt

Answer 24

In German, literally “form.” In reference to perception, a school of thought stressing that the perceptual whole can be greater than the apparent sum of the parts.

Question 25

Gestalt Grouping Rules

Answer 25

A set of rules describing which elements in an image will appear to group together. The original list was assembled by members of the Gestalt school of thought.

Question 26

Good Continuation

Answer 26

A Gestalt grouping rule stating that two elements will tend to group together if they seem to lie on the same contour.

Question 27

Texture Segmentation

Answer 27

Carving an image into regions of common texture properties.

Question 28

Similarity

Answer 28

A Gestalt grouping rule stating that the tendency of two features to group together will increase as the similarity between them increases.

Question 29

Proximity

Answer 29

A Gestalt grouping rule stating that the tendency of two features to group together will increase as the distance between them decreases.

Question 30

Parallelism

Answer 30

A rule for figure-ground assignment stating that parallel contours are likely to belong to the same figure.

Question 31

Symmetry

Answer 31

A rule for figure-ground assignment stating that symmetrical regions are more likely to be seen as figure.

Question 32

Camoflage

Answer 32

To a great extent, this is the art of getting your features to group with the features of the environment so as to persuade an observer that your features do not form a perceptual group of their own.

Question 33

Ambiguous Figure

Answer 33

A visual stimulus that gives rise to two or more interpretations of its identify or structure.

Question 34

Necker Cube

Answer 34

An outline that is perceptually bi-stable. Unlike the situation with most stimuli, most interpretations continually battle for perceptual dominance.

Question 35

Accidental Viewpoint

Answer 35

A viewing position that produces some regularity in the visual image that is no present in the world (e.g., the sides of two independent objects lining up perfectly).

Question 36

Figure-Ground Assignment

Answer 36

The process of determining that some regions of an image belong to a foreground object (figure) and other regions are part of the background (ground).

Question 37

What are the principles for figure-ground?

Answer 37

1) Surroundness
2) Size
3) Symmetry
4) Parallelism
5) Relative Motion

Question 38

Relatability

Answer 38

The degree to which two line segments appear to be part of the same contour.

Question 39

Heuristic

Answer 39

A mental shortcut.

Question 40

Surroundness

Answer 40

A rule for figure-ground assignment stating that if one region is entirely surrounded by another, it is likely that the surrounded region is the figure.

Question 41

Size

Answer 41

The smaller region in an image is likely to be figure.

Question 42

Symmetry

Answer 42

A symmetrical region is more likely to be seen as figure.

Question 43

Parallelism

Answer 43

Regions with parallel contours are more likely to be seen as figure.

Question 44

Relative Motion

Answer 44

How surface details move relative to an edge can also determine which portion of a display is the foreground figure and which is the background.

Question 45

Nonaccidental Feature

Answer 45

A feature of an object that is not dependent on the exact (or accidental) viewing position of the observer.

Question 46

Y and Arrow-Junctions

Answer 46

Almost always correspond to corners and thus don’t signal occlusions.

Question 47

T Junctions

Answer 47

Almost always occur when one surface occludes another.

Question 48

Global Superiority Effect

Answer 48

The finding in various experiments that the properties of the whole object take precedence over the properties of parts of the object.

Question 49

Bayesian Approach

Answer 49

A way of formalizing the idea that our perception is a combination of the current stimulus and our knowledge about the conditions of the world- what is and is not likely to occur. This approach is stated mathematically as Bayes’ theorem: P(A/O)= P(A) x P(O/A)/P(O), which enables us to calculate the probability (P) that the world is in a particular state (A) given a particular observation (O).

Question 50

What are the two factors Bayesian Approach asks us to consider?

Answer 50

1) Before you look at anything, how likely is what you are proposing? This is known as prior probability.
2) How consistent is each hypothesis with observation.

Question 51

Subtraction Method

Answer 51

In functional magnetic imaging, comparison of brain activity measured in two conditions: one with and one without the involvement of the mental process of interest. The difference between the images for the two conditions may show regions of brain specifically activated by that mental process.

Question 52

Decoding

Answer 52

The process of determining the nature of a stimulus from the pattern of responses measured in the brain or, potentially, in an artificial system like a computer network. The stimulus could be a sensory stimulus or it could be an internal state (e.g., the contents of a dream).

Question 53

Pandemonium Model

Answer 53

An account of letter recognition. Selfridge used “demons” as metaphor for processes that we would discuss in neural terms today. Selfridge had an initial early-vision signal-processing stage. Next, features were extracted: orientation lines, curves, and so on. In his third step, a set of “cognitive demons” each looked for the features of one letter. Finally, the “decision demon” pooled information across all the third-layer demons and choose the loudest demon as the answer.

Question 54

Template

Answer 54

The internal representation of a stimulus that is used to recognize the stimulus in the world. Unlike its use in, for example, making a key, a mental template is not expected to actually look like the stimulus that it matches.

Question 55

Structural Description

Answer 55

A description of an object in terms of teh nature of its constituent parts and teh relationships between those parts.

Question 56

Recognition-by-Components Model

Answer 56

Biederman’s model of object recognition, which holds that objects are recognized by the identities and relationships of their component parts.

Question 57

Geon

Answer 57

In Biederman’s recognition-by-components model, any of the “geometric ions” out of which perceptual objects are built.

Question 58

Deep Neural Network (DNN)

Answer 58

A type of “machine learning” in artificial intelligence in which a computer is programmed to learn something (here object recognition). These are artificial neural networks that have a large number of layers of nodes with millions of connections. First the network is “trained” using input for which the answer is known (“that is a cow”). Subsequently, the network can provide answers form input that it has never seen before.

Question 59

Entry-Level Category

Answer 59

For an object, the label that comes to mind most quickly when we identify it (e.g., “bird”). At the subordinate level, the object might be more specifically named (e.g., “eagle”); at the superordinate level, it might be more generally named (e.g., “animal”).

Question 60

Holistic Processing

Answer 60

Processing based on analysis of the entire object or scene and not on adding together a set of smaller parts or features.

Question 61

Prosopagnosia

Answer 61

An inability to recognize faces.

Question 62

Congenital Prosopagnosia

Answer 62

A form of face blindness apparently present from birth, as opposed to acquired prosopagnosia, which would typically be the result of an injury to the nervous system.