Mental speed is not the ‘basic’ process of intelligence

It is argued that a great deal of human intelligence research has unjustly overemphasised the role played by mental speed. While it is accepted that mental speed is an important aspect of intelligence, determination of this as the basic process underlying individual differences is a consequence of flawed logic. This may be attributed to several questionable research practices and/or theoretical shortcomings. These include: (a) The adoption of a narrow neo-Spearmanian model of intelligence; (b) Selective interpretation of the available empirical evidence wherein correlations between mental speed and intelligence measures are actually mediocre and certainly of no greater order of magnitude than many other elementary cognitive processes; (c) A failure to realise that the factorial composition of mental speed may be as complex as that for number correct (i.e. level) measures; (d) The acceptance of two main paradigms in the literature—Choice Reaction Time (CRT) and Inspection Time (IT)—both of which contain a number of unresolved controversies; (e) A tendency to examine in post hoc fashion those parameters of CRT and IT tasks that show correlations with measures of intelligence; (f) The absence of a satisfactory explanatory model to account for the correlations between mental speed and intelligence.