Lecture 5 - Perception 1

Question 1

What is Perception?

Answer 1

Perception is the process by which information acquired from the environment by our sense organs is transformed into experiences of objects, events, sounds, tastes and so on.

Question 2

What kind of process is perception?

Answer 2

Rapid, Automatic, Unconscious process

Question 3

How do perception and sensation interact?

Answer 3

Early work presumed sensation lead to perception - however they probably overlap in time and involve complex interactions
E.g. sensation <-> perception

Question 4

How is the world perceived?

Answer 4

We see the world as full of different objects/forms - for this to occur the perceptual system must organise the sensory info it receives in particular ways.

The most basic distinction is between objects (figures) and backgrounds (grounds)

Question 5

How are objects classified as Figure or Ground?

Answer 5

It does NOT depend on intrinsic properties of the item - rather on the behaviour of the observer. The object being focused on is the Figure, and its surroundings is the Ground - dependant on focus.

Question 6

What is Gestalt Psychology?

Answer 6

An approach to perception developed at the turn of the of the 20th century, which provided early answers to the question of what features of visual information
determine the perception of objects?

Question 7

What is the idea behind Gestalt Psychology?

Answer 7

Gestalt means ‘An organised whole’

The idea is that perception allows us to integrate pieces of information into meaningful wholes. It’s not enough to isolate basic elements - perception depends on the relations between elements

Question 8

What is Grouping?

Answer 8

The perceptual tendency to organize stimuli into coherent groups

Question 9

What did Max Wertheimer develop?

Answer 9

He asked how people are able to perceive a coherent visual world organised into coherent objects - developed a number of Grouping Principles (Gesetze)

Question 10

What are the Grouping Principles/Gesetze?

Answer 10

Proximity, Similarity, Common Fate, Good Continuation, Closure, and Past Experience

Question 11

What is Proximity?

Answer 11

Group nearby figures together - closeness dictates how the brain groups objects together in this principle
E.g.
.. .. .. .. ..
We see this as 5 groups of 2, rather than 1 group of 10

Question 12

What is Similarity?

Answer 12

Group figures that are similar - based on shared features
E.g
- + - + - +
- + - + - +
- + - + - +
We see these as vertical groups do to the similarity of objects in those columns, rather than grouping them in rows

Question 13

What is Common Fate?

Answer 13

Objects that move together (e.g. towards a common fate) are grouped together - such as flocks of birds (we see them as a whole rather than as individual birds)

Question 14

What is Good Continuation?

Answer 14

Where we perceive continuous patterns - e.g. two overlapping lines wouldn’t be split as two U shapes at the point of crossing - we would split them based on their continuity

Question 15

What is Closure?

Answer 15

Where we fill in the gaps - using negative space to imply an image/shape works because of this

Question 16

What is Past Experience?

Answer 16

Over time, learned groups that DO NOT obey the other principles will reliably be observed - familiarity based

Question 17

What two theories were developed to explain the perception of forms?

Answer 17

Template / Prototype models AND Feature Detection models

Question 18

What is the Template/Prototype Models?

Answer 18

Information acquired by the sensory organs is compared to a template/prototype of the object in the visual system

e.g a prototype of a dog is abstracted from many examples, when new sensory info is obtained the brain compares it to the prototype and recognises it as a dog

Question 19

What is the Feature Detection Models?

Answer 19

The visual system encodes images of familiar patterns in terms of distinctive features - collections of important physical features that specify particular items

E.g. Dog features are abstracted, such as fur, four leg, sharp teeth - when new sensory info is obtained its compared to the features and recognised as a dog

Question 20

What type of explanations are Prototype and Feature detection models?

Answer 20

Bottom-up explanations - Bottom-up processes are involved when the perception of an object is formed from the sensory information with little interpretation.

Question 21

How does Context affect perception?

Answer 21

Evidence suggests that human perception also involves top-down processing.
Using top-down processes, what you expect to perceive influences what you actually perceive

Question 22

How do Top-Down vs Bottom-Up + Gesetze interact?

Answer 22

The Gesetze do not sit neatly in either top-down or bottom-up categories, e.g proximity is bottom-up but common fate is top-down

Bottom-up and Top-down were influenced by information processing approach, while gestalt principles were phenomenological - not intended to provide neural explanation etc

Question 23

What is Gibson’s Direct Perception?

Answer 23

That Perception is Active - the perceptual system actively seeks information from the environment to test hypotheses, it does not simply process input

Question 24

What are Affordances?

Answer 24

An affordance is an action that an individual can
potentially perform in their environment. Thus, an object affords what it “means”/ can be used for – e.g. a chair affords sitting, a ball affords picking up /kicking / throwing

Question 25

How do Affordances work with Perception?

Answer 25

The goal of Perception is the identification of the
affordances of objects in our environment. Features of perception identified by previous researchers only relevant as they identify environmental invariants that predict affordances