Copyright 2008 Clark Elliott CSC587 Cognitive Science Professor Clark Elliott Winter Quarter 2008...

Copyright 2008 Clark Elliott

CSC587 Cognitive Science

• Professor Clark Elliott

• Winter Quarter 2008

• Monday Evening


Overview

• Study the human brain as a computational device

• Some lectures on the basics,• Much reading and discussion – hot

newsgroups!• Suitable for ALL CDM graduate students

capable of 500-level work.• Traditionally strong, interesting, peers in

this course.


Did you know…?

• By some estimates, processing power of a 3-year-old human is equivalent to that of all computers in the world put together.

• 100 billion neurons, average 7,000 connections, many types of neurons, many types of connections.

• Highly parallel design

• Specialized architecture


Example topic: Categorization

• Important to human intelligence

• Humans categorize faster and more accurately than any current software models can support – even theoretically


Why study Categorization?

• One pillar of abstract thinking

• Gateway between perception and cognition: DOG has meaning to us without manipulating details of visual / auditory energy waves

• May be a fundamental unit of cognitive processing.


So – how do we do it? We use at least…

• Classical rules• Prototypes• Exemplars• Attribute weighting• Correlated attributes• Base rates• Competitive Learning• Expectation• Spreading activation


We use Classical Rules

• Speak French is sufficient to indicate category human

• Single adult human male is definition of category bachelor

• Human is necessary for category bachelor


We store Exemplars

• We simply store all the exemplars, and the search them in parallel looking for matches

• So, store all bachelors, compare new input for similarity


We use Prototypes

• Create a prototype

• Every successfully categorized new bachelor input tweaks the prototype -- we extract relevant features and save them


Pre-categorize with Expectations

• We often pre-categorize input artifacts before we notice them based on expectations:– Current environment– Activation networks– Scripts


We use Attribute Weighting

• Some features are more important than others, so we use them first and give them more weight when we categorize an item.


We use Correlations

• Sometimes the presence of two or more features indicates, or inhibits, a categorization, but the feature alone does not.

• Puffy eyes in the morning suggest allergy, but not in the presence of empty beer cans


We use Base Rates

• Was the animal that ran across your lawn last night…– A squirrel?– A dog?– A platypus?


So, for categorization…

• The brain has built-in brain hardware and software for each of the above.

• …takes place at the level of single lines in single letters when reading (vertical, straight, bold)

• … helps us analyze philosophical theories (dialectical materialism)

Is this a letter or a number?

BBA C

12B14


Memory

• What color was the door of your house when you were five years old?

• Hinges on left, or right? Open in or out?

• We do not know the limit of human memory.

• Example: we make use of exemplars stored for categorization even though we cannot “remember” them!


Did you know…

• 20 percent of the processing through the eyes is non-visual through the retinohypothalamic tract?

• This non-visual pathway processes irradiance but does not use visual images.

• It is spatial and affects balance, posture, motor function, sensory integration, reasoning, hearing, visualization, symbolic processing, sleep and emotion centers.

• It functions almost the same with the eyes closed!


Did you know…

• That Radin and May, in a very highly controlled experiment repeated the results of Klintman giving evidence that people regularly exhibit sub-second precognition?

0

LIST 3 GREENREDGREENREDBLUEGREENBLUEREDBLUEREDGREENBLUE

1234567891011121314151617181920

0

LIST 4 GREENREDBLUEREDBLUEREDGREENBLUEBLUEGREENREDGREEN

1234567891011121314151617181920


Sort of like this…

• Flash a color word in B&W (e.g., red, green)

• Flash a color bar that matches the word or not.

• Press a button that matches the color bar.

• If the two match, response times are lower for pressing the button.

• Stroop test, showing interference.


~Future Stroop Test

• Flash color word

• Press button that matches word

• Flash a color bar that matches the word or not

• If the colors match, the response times are lower for pressing the button.


Future Stroop…

• But… subject has not yet seen the color bar at the time of the response…!

• True even when the data is collected before a random number generator selects the color bar to be displayed.

• Thus evidence of human pre-cognition, and may help explain results measuring top fighter pilots.


In CSC587, CogSci, we will…

• Learn basics of concepts like categorization, memory, representation, language, symbolic reasoning, perception, visual processing, spreading activation, and modeling of emotions, from the brain science perspective.

• No programming unless you want to• Reading suitable for 500-level course• Much discussion, including newsgroups• Interesting peers!


Clark Elliott is…

• PhD in Artificial Intelligence from Institute for the Learning Sciences, Northwestern

• Full-time professor number ten at CDM

• Research area is Cognitive Models of Emotion, Personality, and the Representation of Stories.

Environment

• The “Horizon ratio”.• Most people see the

buildings as the same size, and the tower as taller.

• The ratio above to below the horizon always gives good information about height (except in illusions). Here we are ½ as tall as the buildings, but 1/8th of the tower

Copyright 2008 Clark Elliott CSC587 Cognitive Science Professor Clark Elliott Winter Quarter 2008...

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