January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20021 Approaches to Perception and Cognition Philosophical, Early, Classic and Modern.

January 4 and 8, 2002

PSYC202-005, Term 2, Copyright Jason Harrison 2002

1

Approaches to Perception and Cognition

Philosophical, Early, Classic and ModernBC 600 to Today


PSYC202-005, Term 2, Copyright Jason Harrison 2002 2

Major epochs• Philosophy (BC 600 - early 1800s)• Early Psychology (early 1800s - early 1900s)• “Classic” Psychology (early 1900s - 1950s)

– Behaviourism (Watson, Skinner)– Gestalt Psychology (Wertheimer, Koffka)

• Modern Psychology (1950s - )– Ecological Optics (Gibson)– Cognitive Psychology (Helmholtz, Marr)

Philosophy (BC 600 - early 1800s)• study of the “soul”; how it remembers,

perceives– eg, Plato, Aristotle, Descartes

• approach: conceptual analysis– analysis of word meanings– inconsistencies in accounts of perception,

cognition– necessary conditions on our experience of

the world

Philosophy (BC 600 - early 1800s) Major Issues• Is the mind separate from the body

(brain)?– no: Monism

• mind is just one aspect of the body• mind cannot exist without the body

– yes: Dualism• mind and body are different substances• mind can exist without body

Philosophy (BC 600 - early 1800s) Major Issues• Is knowledge acquired or innate (built-in)?

– acquired: Empiricism• mind a “blank slate” at birth• cognitive and perceptual abilities acquired from

experience

– innate: Rationalism• mind inherently rational• cognitive and perceptual abilities help organize

our experience, but do not result from it.



Early Psychology (early 1800s - early 1900s)• experimental study of how we perceive

– Fechner, Wundt, Titchener

• approach: psychophysics– perception and cognition broken down into

simple “atomic units”– relating these “atoms” of perceptions to

physical variables, and to each other• eg, how bright must a light be before it is seen



Early PsychologyMajor Assumption:Perception and cognition based on mental “atoms” which are accessible to consciousness, and which can be built up to form complex memories and perceptions.

Structuralism



Early to Classic Psychology New research traditionsHowever, there were problems…

– are atoms really accessible to consciousness?• no: Behaviourism

– can atoms be built up in a simple fashion?• no: Gestalt Psychology



“Classic” Psychology(early 1900s - 1950s)• Behaviourism (Watson, Skinner)

– conscious access cannot provide basis for scientific study• ie, you cannot rely on self-reporting of perceptual

and cognitive processes

– restrict study to those aspects of P & C that can be given objective, physical measurement• eg, ability to learn associations between pairs of

unrelated words



“Classic” PsychologyMajor Assumptions• P & C based on links between stimulus (S)

and response (R)– “mental atoms” replace by “behavioural atoms”,

S-R links

• Problems– stimuli can be very complex (not “atoms”)– responses can be very complex (not “atoms”)– links/thinking can be very complex (not “atoms”)– no study of consciousness



“Classic” PsychologyBehaviourism (Watson, Skinner)• Study of P & C via observables

– stimulus (S) - usually simple: blue light– response (R) - usually simple (eg, eye blink)– links/reflexes between S and R

• Problems– stimuli can be very complex in real life– responses can be very complex in real life– links/thinking/reflexes can be very complex– no study of conscious experience


PSYC202-005, Term 2, Copyright Jason Harrison 2002

12

Approaches to Perception and Cognition

1900ish to Today

www.cs.ubc.ca/~harrison/P202



“Classic” PsychologyGestalt Psychology (Wertheimer, Koffka)

• Stimuli contain more structure than what is in the simple parts

• “The whole is more than the sum of the parts”

• central aspect of perception is the formation of “Gestalts” (configuration)– ie, configurations that emerge from

arrangements of items





Gestalt PsychologyMajor Assumptions• P & C based on wholes that are formed by

automatic processes– independent “mental atoms” replaced by

integrated wholes

• Problems– Gestalts are difficult to describe objectively– Gestalts formation difficult to predict

(although some laws exist)– no idea how Gestalt formation occurs

• eg, built in, learned, incremental, parallel, sequential



Modern Psychology (1950s - )• origins in developments during WW II• influenced by development of

– information theory– computers (artificial intelligence)

• emphasis is on information– information available to organism

• eg, via incoming light

– information processing needed to produce percept, carry out task

• eg, sense light, detect edges, group edges, …



Modern PsychologyMajor Assumptions• human and animal P & C evolved in a particular

environment for specific purposes– eg, survival, reproduction, communication

• utilize computer models and simulations to gain insight into how biological brains work

• focus on information sensing and processing– ecological optics– cognitive psychology



Modern PsychologyEcological Optics (Gibson)• perception is not “for fun”, but is used for

particular tasks– eg, walking, grasping, catching prey

• information picked up is information that is important for tasks– perceptions of ground plane– simple patterns are no good

• pick up of information is direct– ie, no processing needed– ie, observer “resonates” to the information available

-perception of ground plane via texture pattern - texture denser with increasing distance



Ecological OpticsProblems• great idea, hard to apply• how is information picked up?

– what is “resonance”?– can’t program a computer this way

• which information is important?– obvious for some tasks

• eg, landing an airplane

– but not for others• eg, navigating the world wide web



Cognitive Psychology(Helmholtz, marr)• perception is like scientific inference:

– information helps us decide between different possible hypotheses

• internal model created by reweaving perceived information– hypotheses chosen using best guess based

on experience and information available to observer

-Consider an observer that sees an oval…

Observer

-The oval could be due to a circle straight ahead…

-Or an ellipse at an angle.

(Or many other possibilities…)



Are A and B the possibly the same surface?

AB



Cognitive PsychologyAssumptions• information given is usually not enough

to recover “true nature” of objects– need to use knowledge and guesses– final result is hypothesis (with certainty)

• hypothesis formation involves– processes that operate on symbolic

representations of the incoming information– processing is done unconsciously– similar to a computer



Cognitive PsychologyProblems• not clear that brain is like a computer

– we know computers are not like brains– brains may not use symbolic representations

to create an internal “copy” of the world

• inapplicable to conscious experience– computers are never conscious?



Finally…• What was the purpose of this

presentation?

• Which question remains unanswered?

January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20021 Approaches to Perception and Cognition Philosophical, Early, Classic and Modern.

Documents

s early psychology

s classic psychology

s study

stimulus s

gestalt psychology slide

s major issues

body slide

copyright jason harrison