Qualitative Invariant Effects Arise from Neural Constraints: Common Architecture and Sources of Individual Differences

The distinction between qualitative and quantitative effects can be meaningfully related to the distinction between “architecture” and “model” in computational cognitive science. In turn, this distinction can be related to differences between the invariant systems-level organization of the human brain and individual differences in structural and functional activity. Taken together, this presents an iterative new way to answer Newell’s “20 Questions” problem and to systematize psychological effects as belonging to either architecture or the individual variations within it. Although some limits to this approach exist (for example, Individual differences in strategy might affect whether an effect is qualitative or quantitative), the approach might also shed light on how to account for special populations (neurological or psychological patients) within the same framework.