ABSTRACT
Thus far we have examined how well humans learn concepts from categorical stimuli that are defined by dimensions shared by their members. In the first part of this chapter, we propose the challenge of accounting for the learnability of other, more esoteric, but key concepts. The concepts that we shall consider are concepts defined by two states, “absence” or “presence,” on a single property over four objects. For example, consider two pairs of objects with both objects in one of the pairs possessing the property “triangular” and both objects in the other pair not possessing the property. As we shall explain, such a concept is consistent with the structural meaning of the logical connective known as “if and only if.” Indeed, these are concepts learned from categories that are defined by the 16 possible Boolean functions or operators. Some of these operators are well-known (e.g., “or”, “and”, and “if-then”); however, the majority are not.
