The neurophysiological bases of high IQ

It is suggested that the study of human intelligence must ultimately involve the study of brain processes which limit the availability of information. Consideration of EEG/intelligence studies suggests that inconsistent findings may have arisen partly from the expectation of simple rectilinear relationships where relationships are likely to be curvilinear. There are also theoretical and technical problems such that it is difficult to specify what conventional EEG procedures measure. The EEG evoked potential (EP) data described in this paper were obtained with a new and more powerful analytical procedure based on methods and concepts of systems analysis. With this procedure, EP responses are used to ascertain the relative values of parameters which quantify differences in the transmission characteristics of thalamocortical neuron populations. The results obtained from a study of 48 subjects indicate that high IQ is associated with combinations of neurological parameters which determine an intermediate degree of "arousability" in the cerebral cortex and related structures. This relationship is accounted for in terms of the generally optimal effect that an intermediate degree of arousability would have on different neurophysiological processes mediating the acquisition, retention and utilization of information. Thus, with some important qualifications, middling arousability can be conceived as the neurophysiological basis of high general intelligence or "g".