ABSTRACT
An interest in measuring processing speed (PS) has been prevalent since the early days of psychology. For example. while investigating individual differences in mental ability. British scientist Sir Frances Galton. theorized that higher intelligence is a result of faster "mental speed" (Galton. 1883). Although his attempts to demonstrate an association between reaction time (RT) and IQ were unsuccessful. subsequent research suggests that differences in psychometric intelligence may be largely dependent on mental speed (Eysenck. 1986; Jensen. 1982; Vernon. 1987; see Deary & Stough. 1996 for a review). As psychology's appreciation of the relationship between PS and intelligence has evolved, efforts to refine PS as a construct and to identify the variables that contribute to individual differences in PS have been undertaken. This line of research suggests that PS is related to a number of factors, including age, education, gender, and intelligence (Barrett, Eysenck. & Lucking. 1986; Brittain, La Marche. Reeder. Roth. & Boll. 1991; Stuss. Stethem. & Pelchat. 1988; Wiens. Fuller. & Crossen. 1997). The reader is referred to chapter I in this book for a review of PS and intelligence.
