Dual-processing models of cognitive/intellectual performance

Dual processing models of cognitive ability have been prevalent in the psychology literature for decades. During the past decade the two different modes of cognitive processing have been referred to as System I and System II. I've always found the dual-system theories of significant interest, but I had a difficult time making sense of a variety of different dual system models and theories.

Thus, I was extremely excited to recently run across a Annual Review of Psychology article on the topic of dual-processing cognitive models by Jonathan Evans (2008).  Below are the highlights of the Evans article together with select summary tables that are excellent sources for integrating the various due process models (the following abstracted statements are from the review-emphasis to Evans statements, as added by the blog master, are designated by italics and/or underlining.).  I particularly like Evans recommendation to refer to these two types of processing as type I and type II and the critical distinction between the involvement of complex working memory. 

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• Close inspection of the evidence suggests that generic dual-system theory is currently oversimplified and misleading

• We might be better off talking about type 1 and type 2 processes since all theories seem to contrast fast, automatic, or unconscious processes with those that are slow, effortful, and conscious (Samuels 2006). Such terminology does not commit use to a two-system view. However, it would then be helpful to have some clear basis for this distinction

• My suggestion is that type 2 processes are those that require access to a single, capacity-limited central working memory resource, while type 1 processes do not require such access. This implies that the core features of type 2 processes are that they are slow, sequential, and capacity limited. The last feature implies also that their functioning will correlate with individual differences in cognitive capacity and be disrupted by concurrent working memory load. Depending upon what else is assumed about working memory, there may be a rationale for describing such type 2 processes as registering in consciousness and having properties associated with executive processes and intentional, higher-order control.

• If there are indeed multiple kinds of type 1 processes, then it is to be expected that psychologists will have developed different kinds of dual-process theories, which seems to be the case.

• The problem with this distinction is that type 1 processes then simply refer to any processes in the mind that can operate automatically without occupying working memory space. As already indicated, there are a number of different kinds of such implicit processes.

• In short, my conclusion is that although dual-process theories enjoy good empirical support in a number of fields of psychology, the superficially attractive notion that they are all related to the same underlying two systems of cognition is probably mistaken, at least in the way that Systems 1 and 2 are being defined in the current literatures.

• It is perfectly possible that one system operates entirely with type 1 processes and that the other includes a mixture of type 1 and type 2 processes, the latter being linked to the use of working memory, which this system uses—among other resources. Such a proposal could resolve the conflict between evidence for dual systems on the one hand with the proposals of different dual-process theorists on the other.