Copyright 2008 Clark Elliott CSC587 Cognitive Science Professor Clark Elliott Winter Quarter 2008 Monday Evening

Copyright 2008 Clark Elliott 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.

Copyright 2008 Clark Elliott 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

Copyright 2008 Clark Elliott Example topic: Categorization Important to human intelligence Humans categorize faster and more accurately than any current software models can support – even theoretically

Copyright 2008 Clark Elliott 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.

Copyright 2008 Clark Elliott 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

Copyright 2008 Clark Elliott 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

Copyright 2008 Clark Elliott 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

Copyright 2008 Clark Elliott We use Prototypes Create a prototype Every successfully categorized new bachelor input tweaks the prototype -- we extract relevant features and save them

Copyright 2008 Clark Elliott Pre-categorize with Expectations We often pre-categorize input artifacts before we notice them based on expectations: –Current environment –Activation networks –Scripts

Copyright 2008 Clark Elliott 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.

Copyright 2008 Clark Elliott 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

Copyright 2008 Clark Elliott We use Base Rates Was the animal that ran across your lawn last night… –A squirrel? –A dog? –A platypus?

Copyright 2008 Clark Elliott 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?

Copyright 2008 Clark Elliott 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!

Copyright 2008 Clark Elliott 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!

Copyright 2008 Clark Elliott 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 3GREEN RED GREEN RED BLUE GREEN BLUE RED BLUE RED GREEN BLUE

0 LIST 4GREEN RED BLUE RED BLUE RED GREEN BLUE GREEN RED GREEN

Copyright 2008 Clark Elliott 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.

Copyright 2008 Clark Elliott ~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.

Copyright 2008 Clark Elliott 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.

Copyright 2008 Clark Elliott 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!

Copyright 2008 Clark Elliott 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 1/8 th of the tower