Introduction

There is an unlimited variety of human mental abilities, defined as any form of information processing capability that can be assessed objectively and quantitatively by means of psychometric tests or various laboratory apparatuses. Information processing includes diverse cognitive functions such as stimulus apprehension, attention, perception, sensory discrimination, generalization, conditioning, learning, short-term and long-term memory, recall, learning-set acquisition, concept formation, thinking, reasoning, inference, problem solving, planning, invention, and use of language. Quantitative assessments of such information processing functions by objective means typically show a wide distribution of individual differences. It is well established in psychometrics that individual differences in a wide variety of cognitive tasks, however diverse in specific knowledge content and required skills, are all positively correlated in the general population. This phenomenon of all-positive ...