1. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20021 Approaches to Perception and Cognition Philosophical, Early, Classic and Modern BC 600 to Today

2. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20022 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)

3. 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

4. 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

5. 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.

6. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20026 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

7. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20027 Early Psychology Major 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

8. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20028 Early to Classic Psychology New research traditions However, there were problems… –are atoms really accessible to consciousness? no: Behaviourism –can atoms be built up in a simple fashion? no: Gestalt Psychology

9. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 20029 “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

10. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200210 “Classic” Psychology Major 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

11. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200211 “Classic” Psychology Behaviourism (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

12. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200212 Approaches to Perception and Cognition 1900ish to Today www.cs.ubc.ca/~harrison/P202

13. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200213 “Classic” Psychology Gestalt 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

17. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200217

18. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200218 Gestalt Psychology Major 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

19. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200219 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, …

20. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200220 Modern Psychology Major 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

21. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200221 Modern Psychology Ecological 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

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

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

24. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200224 Ecological Optics Problems 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

25. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200225 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

26. -Consider an observer that sees an oval…

27. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200227

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

29. -Or an ellipse at an angle. (Or many other possibilities…)

30. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200230 Are A and B the possibly the same surface? A B

31. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200231 Cognitive Psychology Assumptions 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

32. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200232 Cognitive Psychology Problems 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?

33. January 4 and 8, 2002PSYC202-005, Term 2, Copyright Jason Harrison 200233 Finally… What was the purpose of this presentation? Which question remains unanswered?