THE STRING MEASURE OF THE ERP - WHAT DOES IT MEASURE

The event-related brain potential (ERP) has been investigated extensiv ely inan effort to understand the neurophysiological bases of intellig ence. Measures derived from the ERP have been used as indices of intel ligence, particularly the string measure of the complexity of the ERP. However, the string measure has been criticised for being non-specifi c and for being dependent on ERP amplitude. These criticisms were test ed by investigating relationships between ERP string measure, ERP ampl itude measures, and the ERP power spectrum. It was found that the stri ng measure was non-specific in that it indexes both low and high frequ ency event-related activity; the string measure is also dependent on E RP amplitude. The string measure is therefore not a valid measure of t he ERP. It was concluded that the string measure should be abandoned; human intelligence cannot map in a simple way onto gross measures of s calp-recorded electrocortical activity. (C) 1997 Elsevier Science B.V.