Object Perception

Question 1

Object perception

Answer 1

involves obtaining a description of
shape, size, material composition, etc. from light
information

Question 2

Object recognition

Answer 2

the matching of some description obtained by perception with something previously stored in memory

Question 3

“Basic level” recognition

Answer 3

categorization, such as “chair”

Question 4

Grouping / Unit Formation

Answer 4

the brain must group different parts of the retinal image in order to identify an object

Question 5

Segmentation

Answer 5

how the brain separates the visible world into separate objects

*problem: we don’t know how the brain does it, even before perception occurs

Question 6

Object perception

Answer 6

extracting a description of shape, color, size, material composition, etc. from sensory/light information

–> traditionally thought of as lower level processing

Question 7

Object recognition

Answer 7

the comparison of some description obtained by perception with something previously stored in memory

• previously stored information can be a category, such as “chair” …or an instance, such as “my favorite lounge chair with the big cushions.”
• most research on object recognition involves categorization (so-called “basic level” recognition)

*all recognition research presupposes some description
obtained from perception.

–> traditionally thought of as higher level processing b/c it involves memory

Question 8

Basic Level Recognititon

Answer 8

Most research on object recognition involves categorization (so-called “basic level” recognition)

e.g. “chair”

Question 9

Specialized Categorization/Recognition

Answer 9

subordinate level under a basic categorization

e.g. office chair instead of just chair

Question 10

Important edges are given by differences in…

Answer 10

• luminance
• color
• motion
• depth
• texture

*the brain must rely on statistics, educated guesses

Question 11

Junction detection and classification (T, X, L, Y)

Answer 11

Occluding edges usually have “T” junctions

Transparency signaled by “X” junctions

Object corners have “L” junctions

Corners of 3D Objects hav “Y” junctions

Question 12

Gestalt principles

Answer 12

Classical approach to explaining brain’s process for Segmentation and Grouping in Object Perception Tasks

• -> Gestalt = overall form (put together, organized structure)
• -> Perception of a WHOLE thing( e.g., object, scene, etc) is more than the sum of its parts

Question 13

Gestalt Principles

Answer 13

• Good continuation
• Similarity
• Proximity
• Common fate
• Closure
• Symmetry
• Simplicity or good figure

Question 14

Gestalt Principle of Good Continuation

Answer 14

continuous forms are favored over discontinuous ones

Question 15

Gestalt Principle of Similarity

Answer 15

similarity can group things together (e.g. size, shape, orientation, etc)

Question 16

Gestalt Principle of Proximity

Answer 16

being close to each other can help group

Question 17

Gestalt Principles of Common Fate

Answer 17

things that move together tend to be grouped together

Question 18

Gestalt Principles of Closure

Answer 18

the perceptual system favors things that are closed rather than all over the place

*perceiving a connection or continuity between elements
which do not touch each other
*the tendency to complete figures even when part of the information is missing

Question 19

Gestalt Principles of Symmetry

Answer 19

symmetrical shapes are perceived collectively.

Question 20

Gestalt Principles of Simplicity or Good form

Answer 20

interpretations that consist of simple objects are preferred over interpretations that consist of complex objects

Question 21

Gestalt Principles of Figure-ground

Answer 21

some objects are perceived as figure and some as
ground, but never both at the same time

(jazz musician vs face example)

Question 22

RSVP

Answer 22

rapid serial visual presentation
firing of images in a series, participant is given a task of pressing a button when they see a specific image

rate: 50/100 milliseconds is enough time to perform this task (shocking) –> object perception is fast!

Question 23

Why is the speed of object perception considered controversial?

Answer 23

The rate of processing through the pipeline may be fast, but the time needed to process an object might be slower (estimated to be about 500 milliseconds/half a second)

Question 24

Problem of Occlusion

Answer 24

There are different fragments in the visual field that belong to an object, but are occluded by another object

• -> the brain must know which fragments belong to which object (grouping)
• -> we don’t know how the brain does grouping