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Monday, January 31, 2011

Physiological correlates of intelligence

How fast is your nervous system?
In parallel with these studies, there has been challenging research on physiological correlates of intelligence. Much of this research was championed in its earliest stages by Hans Eysenck (1988), who was also exploring physiological correlates of personality at the time, and with whom Jensen had worked. Research has found correlations between IQ and brain evoked potentials (Deary & Caryl, 1993), cerebral glucose metabolism (Haier, 1993) and nerve conduction velocities (Reed & Jensen, 1991, 1992). Deary and Caryl (1997) provide a comprehensive and positive review of the evidence for a physiological basis to differences in intelligence, although some researchers remain unconvinced (Howe, 1997). There is also a growing swathe of brain-scan studies which use magnetic resonance imaging to examine neural activation changes during thoughtful activity in healthy control participants and in patients with diseases such as Alzheimer’s, which affects intellectual functioning. Considered together with the robust evidence from inspection time and reaction time studies, the hypothesis that a biological variable might form the basis of general intelligence has received increasing support. This variable is best thought of as reflecting differences between individuals in the speed or efficiency with which information in transmitted in the nervous system.

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