Pergamon zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Person. indiuid. D# Vol. 20, No. 6, 775-800, 1996 pp. Copyright 0 1996 Elsevier Science Ltd Printed in Great Britain. All rights rewvcd S0191-8tI69(96)00022-0 0191-8869/96 515.00+0.00 THE RELATIONSHIP BETWEEN SPEED OF INFORMATION PROCESSING AND COGNITIVE ABILITY Alison C. Bowling and Brian D. Mackenzie Department of Psychology, University of Tasmania, Box 525C G.P.O., Hobart, Tasmania, Australia f Received 8 March 1995: received zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK for publication 24 January 1996) Summary-Speed of information processing as measured by various reaction time and inspection tasks has been shown to correlate with psychometric intelligence, and it has been suggested that general intel- ligence (g) is determined to some degree by the speed that information is processed. If this is so, then various measures of speed of information processing should correlate substantially with each other, and each should also correlate with a wide range of psychometric tests that load on g. Alternatively, intelligence may be considered to be a multi-faceted complex of partially related abilities with specific abilities being dependent upon specific cognitive processes. If this is the case, it should be possible to discover independent cognitive processes, some of which correlate with one facet or broad ability and some with another. This paper presents three experiments in which the relationship between intellectual ability and four speed of information processing measures was examined. These were rate of memory scanning, rate of retrieval of information from long term memory, speed of stimulus-response mapping and inspection time (IT). Results showed that correlations between IT and most reaction time measures of speed of information processing were low, and that correlations between different versions of IT were negligible. In addition, some cognitive tasks with verbal material (memory scanning rate for digits and Posner letter matching IT) correlated most substantially with Verbal Reasoning whereas non-verbal (two-line) IT consistently correlated with tests loading on g. It was thus suggested that while non-verbal IT may be a measure of a perceptual speed attribute that contributes to mental functioning, other “speed of information processing” parameters may be more specific to a subset of abilities. Copyright 0 1996 Elsevier Science Ltd INTRODUCTION The study of human intelligence has occupied psychologists for almost a century. Until the last 20 years the basic approach has been the psychometric one that began with Binet and Spearman. Concepts of psychometric intelligence range from considering it to be a measure of a general underlying mental ability (usually referred to as g), to understanding it to comprise a wide range of different abilities. An hierarchical concept of intelligence has been developed by Horn (1987) in which a broad general measure of IQ or g, is combined with a number of second order abilities. These comprise fluid, or broad reasoning intelligence, Gr, crystallized, or acculturation knowledge, G,, broad speediness, G,, short-term acquisition and retrieval, SAR, long-term storage and retrieval, TSR, broad visual intelligence, G, and broad auditory intelligence, G,. Each of these abilities is measured by a range of related tests. An alternative to the psychometric approach to human ability has recently gained momentum. This information processing or cognitive correlates approach attempts to understand the mental processes which contribute to intellectual functioning. Cognitive tasks which correlate significantly with scores on ability tests are sought. Tasks which have been investigated include simple tests of pure speed (simple reaction time) as well as more complex reasoning tasks (Sternberg, 1985). In general, the simpler the task the lower and the less consistent the correlation with scores on ability tests (e.g. Larson & Saccuzzo, 1989). One basic hypothesis from which the information processing approach derives its impetus is that the rate of transmission of information through the cortex influences, or even determines, intel- ligence. Various measures of speed of information processing are thought to be estimates of this basic transmission rate, and attempts have been made to relate these measures to intelligence. Jensen (1982, 1987a) has extensively studied many reaction time (RT) parameters and demonstrated that these correlate modestly with g as estimated using Raven’s Progressive Matrices. The correlation is generally quite low for simple RT, but more considerable correlations have been obtained between choice RT and g, especially when the number of choices is large. These findings have been confirmed by many researchers (e.g. Neubauer, 1990) so that the RT/IQ relationship appears to be fairly well