Evoked potential correlates of intelligence: some problems with Hendrickson's string measure of evoked potential...

The string measure of evoked potential (EP) complexity is based on a new error theory of intelligence, which differs from the older speed-based formulations which focus on EP latency rather than complexity. In this note we first raise a methodological problem of arbitrariness with respect to one version of the string measure. We then provide a comparative empirical assessment of EP-IQ correlations with respect to a revised string measure (which does not suffer from the methodological problem), a latency measure, and another measure of EP complexity: average voltage. This assessment indicates that the string measure, in particular, yields quite disorderly results, and that, in general, the results favor the speed over the error formulation.