1. A method of verifying whether a particular individual is a member of a predetermined group, said method comprising: generating a first timing vector relating to an authorized individual as a function of the time delays between successive input operations by said authorized individual, said time delays being neurophysiologically determined and unique for each authorized individual; storing said a first timing vector; generating a second timing vector of an individual to be identified as a function of the time delays between successive input operations, said time delays being neurophysiologically determined and unique for each individual to be identified; and comparing the first and second timing vectors to determine the statistical similarity therebetween.