Elucidating the Functional Relationship Between Speed of Information Processing and Speed-, Capacity-, and Memory-Related Aspects of Psychometric Intelligence.

Numerous studies reported a positive relationship between speed of information processing (SIP) and the g factor of intelligence. Only very few studies, however, examined SI P's relationship to speed-, capacity-, and memory-related aspects of psychometric intelligence. In order to further elucidate this relationship, a Hick reaction time task and the Berlin Intelligence Structure (BIS) test were administered to 240 participants. From the BIS test, indicators of BIS -Capacity, BIS -Speed, and BIS -Memory were determined. By means of fixed-links modeling, we subdivided variance in reaction time from the Hick task into a component representing individual differences in speed directly related to the systematically increased number of possible responses and another component representing individual differences in speed associated with residual sources unrelated to the experimental variation of response alternatives. While the former speed component was primarily related to BIS -Capacity and, to a lesser extent, to BIS -Speed, the latter one was only weakly related to BIS -Speed but unrelated to BIS -Capacity. None of the two speed components from the Hick task showed an association with BIS -Memory. Our findings indicate that individual differences in SI P caused by experimentally increasing the number of possible responses were more strongly associated with capacity- than with speed-related aspects of psychometric intelligence. In addition, individual differences in SI P not associated with the experimental manipulation of response alternatives showed rather weak relationships to each of the three BIS operations and could be considered equally strong.