Week 5: Perceiving objects part 1

Question 1

Gestalt psychology

Answer 1

• a school of psychology concerned with how perceptual organisation is achieved

Question 2

Feature detection

Answer 2

A theoretical approach, most commonly in pattern recognition, in which stimuli/ patterns are identified by breaking them up into their constituent features.

Question 3

Perceptual constancy

Answer 3

tendency of humans to see familiar objects as having standard shape, size and/or colour, regardless of changes in the angle, pov, distance or lighting.

Question 4

Agnosia

Answer 4

a deficit in the ability to name objects that arises from brain damage

Question 5

Holistic processing

Answer 5

Involves the integration of info from an entire object

Question 6

Propoagnosia

Answer 6

(face blindness) Individuals experience poor face recognition, but good object recognition

Question 7

Detecting features: bottom-up processing

Answer 7

stimulus driven, very simplistic

• Based on bottom-up processing, we can see 3 pie-like circles and pink V-shapes

Question 8

Feature detecting: Top-down processing

Answer 8

Concept-driven
(e.g. if can’t see whole object, rely on interpretation, past experience, prior knowledge more complex)

- Based on top-down processing, our existing knowledge allows us to see a triangle in the middle

Question 9

Gestalt psychology

Answer 9

(derived from German word meaning ‘form’ or ‘appearance’)

	* Concerned with how perceptual organisation is achieved
	
	* Describe how we separate and link (or parse) into individual objects

Question 10

Parse

Answer 10

how we separate/ link different objects

Question 11

Guiding principles of prägnanz: meaning

Answer 11

when people are presented with complex shapes or a set of ambiguous elements, their brains choose to interpret them in the easiest manner possible

Question 12

Guiding principles: Similarity principle

Answer 12

Group together objects that resemble each other

Question 13

Guiding principles: proximity principle

Answer 13

The closer objects are to each other, the more likely we are to group them together perceptually

Question 14

Guiding principles: Good continuation

Answer 14

Prefer to organise objects where contours continue smoothly
(brain would prefer to see it at one whole object, rather than 2 separate ones)

Question 15

Guiding principles: closure

Answer 15

Bias toward perceiving closed objects rather than incomplete ones

Question 16

Guiding principles: Simplicity

Answer 16

Interpret an object in the simplest way possible

Question 17

Guiding principles: Figure-ground segregation

Answer 17

Separating an object from its background

relies on past experience/learning - not innate!

Question 18

Gestalt psychology: strengths

Answer 18

• Focuses on fundamental issues
  
  • Principles applicable to complex images
• Simplicity is key!

Question 19

Weaknesses

Answer 19

• Deemphasised the importance of past experience
  
  • Provide descriptions (not explanations) of perceptual phenomena
  • Principles of perceptual organisation based on 2D drawings (applicable to real life?)

Question 20

Feature detection theories

Answer 20

A simple pattern, fragment or component
– Appears in combination with other features across a variety of stimuli

Question 21

Visual search

Answer 21

Pps Indicate as quickly as you can whether a particular target is present (an odd one out) (Treisman, 1986)

Takes longer when searching for a combination of features

Question 22

Feature Nets

Answer 22

– bottom-up - Piece together features of the stimuli - from features, to letters to the word

• Top-down - When pps primed with images of animals, they’re more likely to choose an animal word

Question 23

Geometric ions

Answer 23

All objects reduced to geometric ions/ shapes (“geons”)

Recognition-by-components (RBC) theory… components = geons

Question 24

Recognition-by-components (RBC)

Answer 24

• Perceiving components is the first major step in object recognition
  
  • Object recognition is a joint effort between two processes:
    
    1. One responsible for features and components
    2. Another for overall shape and global patterns

Question 25

Evidence for RBC

Answer 25

* If a pattern is degraded (parts missing), it matters where it is degraded * Non-recoverable objects – Vertices (point where two lines meet) missing – Cannot or take longer to recognise object * Recoverable objects – Segments of smooth, continuous edges missing – Easy to fill-in missing parts and recognise object Biederman (1987)

Question 26

Weaknesses

Answer 26

* Tied to bottom-up processing * Some evidence contradicts the “features-first” aspect of the model – Whole object can be perceived rapidly and automatically * Embodied cognition – Perception of objects influenced by our expectation of how we will interact with those objects

Question 27

Summary so far

Answer 27

* Object perception is complex – Detect different features (bottom-up) – Interpret features (top-down) * Gestalt Psychology – prägnanz – Similarity; proximity; good continuation; closure; simplicity; figure-ground segregation * Theories of object perception – Feature nets – Recognition-by-components (geons)