Green’s Tri-Level Hypothesis Behavioral: a person’s performance on specific experimental tasks Cognitive: the postulated cognitive or affective systems underlying the behavior Biological: the nature of the brain systems as affected by genetic, environmental, and social factors that mediate the cognitive systems

The Basic Questions For the normal, typical adult, what is the human capacity to X? How does a normal, typical adult (exercise his or her capacity to) X? How does the capacity to X of the normal, typical adult interact with the rest of his or her cognitive capacities?

Computational Assumption (mechanistic, but not reductive) Linking Assumption: The human mind or brain is a computational device (computer); hence, human cognitive capacities consist, to a large extent, of a system of computational capacities System Assumption: A computer is a device capable of automatically inputting, storing, manipulating, and outputting information in virtue of inputting, storing manipulating, and outputting representations of that information. These information processes occur in accordance with a finite set of rules that are effective and that are, in some sense, in the machine itself

Representational Assumption Linking Assumption: The human mind or brain is a representational device; hence, human cognitive capacities consist of a system of representational capacities. System Assumption: A representational device is a device that has states or that contains within it entities that are representations. Any representation will have four essential aspects to its being a representation.

4 essential aspects essential for a representation will be realized by a representation bearer will represent one or more representational objects representation relations will be grounded somehow will be interpretable by (that is, will function as a representation for) some currently existing interpreter

Methodological Assumptions Basic questions can be presented in narrow information processing terms Study of human cognition can focus on the individual in the natural environment; culture and society gain their effects through mental representation Cognition can be studied independently from affect and personality Each cognitive capacity can be studied independently We can distinguish ‘normal’ from ‘abnormal’ cognition Adults are alike enough to allow for talk of ‘typical’ cognition

More Assumptions Explanatory strategy of cognitive science is sound Scientific methods rule (empirical data!) Complete theory of cognition requires contributions from all cognitive science’s subdisciplines Information processing answers to basic questions are constrained by neuroscience

Marr’s Levels of Explanation (equal to Green’s levels) Computational Task, behavior: What do people do, given specific tasks Algorithmic Cognitive: What cognitive of affective systems underlie the behavior Implementational Biological, brain: The basic systems, as affected by genetic, environmental, and developmental factors

Summary Cognitive science aims to understand: The processes and representations underlying intelligent action in the world It does so by building and testing: Explicit models of these processes Complete models have at least 3 levels: Computational (behavioral) Algorithmic (cognitive) Implementational (biological)