Electrophysiology, chronometrics, and cross-cultural psychometrics at the Biosignal Lab: Why it began, what we learned, and why it ended

This article is about why and how Hans Eysenck began investigating the brain evoked potential and sensory nerve conduction correlates of psychometric IQ, his investigations into the timed/speeded performance (chronometrics) results being published by Art Jensen, and the initial results being reported by Doug Vickers and Ted Nettelbeck on the relation of Inspection Time to psychometric IQ. In the midst of this experimental work, Hans and Sybil Eysenck were also engaged in the final stages of their multi-country investigation into the universals of human personality and temperament, using the Eysenck Personality Questionnaire (EPQ). Although many regarded both the experimental and cross-cultural work as 'mildly amusing but not his best work', we did actually learn a great deal from these efforts. (1) None of the previously reported evoked potential parameter correlations with psychometric IQ replicated with any substantive consistency. Neither did the sensory nerve conduction parameters. (2) The expected relationship between Reaction Time parameters and psychometric IQ was replicable, but theoretically and scientifically deficient. Why? Because we observed many individuals with low IQ possessing reaction times faster than high IQ individuals, even when retested on a second occasion. (3) The expected relationship between Inspection Time parameters and psychometric IQ was replicable, but again, theoretically and scientifically deficient. Too many cases were observed showing the opposite of the expected effect (i.e. low IQ individuals possessed much shorter Inspection Times than high IQ individuals). (4) The four personality constructs assessed with the EPQ showed 'good enough' replicability within datasets acquired across 35 different countries, although the Psychoticism scale was the weakest in terms of factor recovery.