Frankfurt -- Philosophical Certainty -- The Philosophical Review -- V71n3pp303-327
January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20021 Approaches to Perception...
-
date post
19-Dec-2015 -
Category
Documents
-
view
214 -
download
1
Transcript of January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20021 Approaches to Perception...
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
January 4 and 8, 2002
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.
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 6
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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 7
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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 8
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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 9
“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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 10
“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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 11
“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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002
12
Approaches to Perception and Cognition
1900ish to Today
www.cs.ubc.ca/~harrison/P202
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 13
“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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 17
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 18
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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 19
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, …
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 20
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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 21
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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 24
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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 25
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…)
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 30
Are A and B the possibly the same surface?
AB
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 31
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
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 32
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?
January 4 and 8, 2002
PSYC202-005, Term 2, Copyright Jason Harrison 2002 33
Finally…• What was the purpose of this
presentation?
• Which question remains unanswered?