Foundations Of Cognitive Science

Classical Sandwich

Imagine a very simple agent that was truly incapable of representation and reasoning.  Its interactions with the world would necessarily be governed by a set of reflexes that would convert sensed information directly into action.  These reflexes define a sense-act cycle (Pfeifer & Scheier, 1999).

In contrast, a more sophisticated agent could use internal representations to decide upon an action, by reasoning about the consequences of possible actions, and by choosing the action that was reasoned to be most beneficial (Popper, 1978). “While an uncritical animal may be eliminated altogether with its dogmatically held hypotheses, we may formulate our hypotheses, and criticize them.  Let our conjectures, our theories die in our stead!” (p. 354).  In this second scenario, thinking stands as an intermediary between sensation and action.  Such behavior is not governed by a sense-act cycle, but is instead the product of a sense-think-act cycle (Pfeifer & Scheier, 1999).

Hurley (2001) has argued that the sense-think-act cycle is the stereotypical form of a theory in classical cognitive science; she called this form the classical sandwich.  In a typical classical theory perception can only indirectly inform action, by sending information to be processed by the central representational processes, which in turn decide which action is to be performed.


  1. Hurley, S. (2001). Perception and action: Alternative views. Synthese, 129(1), 3-40.
  2. Pfeifer, R., & Scheier, C. (1999). Understanding Intelligence. Cambridge, MA: MIT Press.
  3. Popper, K. (1978). Natural selection and the emergence of mind. Dialectica, 32, 339-355.

(Added September 2010)