SENSORY NERVE-CONDUCTION AND INTELLIGENCE - A REPLICATION

A replication was undertaken of our previous work relating the conduction parameters of variability and velocity of the electrically stimulated peripheral median nerve to psychometric test IQ and EPQR Psychoticism. Once again, we failed to find any significant correlation between measures of nerve conduction velocity and IQ. Further, we failed to replicate a previous correlation of 0.37 between EPQ Psychoticism and conduction velocity. However, we did partially replicate the correlation between conduction variability and IQ, although the statistical significance of this correlation depended upon a correction for an excessive restriction of range in IQ and on the notion of an order effect in the testing procedures. Finally, it was demonstrated that the measurement of nerve conduction velocity via just-above-threshold stimulus levels yielded measurement reliability and parameter stability equal to that found using supramaximal stimulation.