Simply put, cognition is computation, computation operates over symbols, symbols begin with inputs to the brain and end with outputs from the brain, and so it is in the brain alone that cognition takes place, and it is with the brain alone that cognitive science need concern itself.

So, despite the web of causal relations between organisms and environments, we suppose the mind must be in a separate place, within some boundary that sets it apart from the world.

In contrast, Sternberg’s reaction time measure does apparently reflect unconscious cognitive processing. The measure shows that comparison of the test stimulus with items of the memorized set takes approximately 38msec per item. This is quite fast. So fast, Sternberg claims, that “the scanning process seems not to have any obvious correlate in conscious experience. Subjects generally say either that they engage in a self-terminating search, or that they know immediately, with no search at all, whether the test stimulus is contained in the memorized list” (1969: 428). This comment raises another problem with Newell and Simon’s procedure. Apparently subjects’ conscious reports can in fact misrepresent unconscious cognitive activity. Whereas Sternberg’s subjects might claim to have engaged in a self-terminating search (or no search at all!), the reaction time measurements tell a different story. Given this inconsistency between the subjects’ reports and the experimental data, there is further reason to doubt that the reports on which Newell and Simon rely accurately reflect the unconscious processes that humans use when solving logic problems.

The conditions for being a symbol do not, apparently, mandate that symbols be made of any particular stuff, but instead focus on functional criteria, on criteria about what symbols must do. Among the relevant conditions seem to be these. First, symbols can “stand for” or represent things. The words “lamb” and “αρνι´” are both symbols, and both happen to represent the same wooly object. Similarly, the numeral “12” represents the number twelve, as does “XII.” And while “X” can represent the number ten, when found on a map it can represent the location of a treasure chest. A band of gold, when worn on a finger, can also be a symbol, representing, as it often does, devotion.