Abstract: There is now a new tendency in the field of intelligence, researchers attempt to discover the correlation between psychometric intelligence to a cognitive or psychophysical variable, and employ cognitive and biological approaches in the same studies. This research emphasis is mental speed, which is indexed by inspection time (IT), reaction time, ERP or nerve conduction velocity. Many studies suggest that, in IT task, the patterns of amplitude and latency period of ERP are different between higher IQ and lower IQ participants. Many findings demonstrate that both information processing speed and nerve conduction velocity have a higher correlation with intelligence g factor, and that the cross-disciplinary studies on the relationship between intelligence and mental speed have become an important approach

Key words: intelligence g factor, mental speed, inspection time, ERP