Process differences and individual differences in some cognitive tasks

This study is based on three distinct elementary cognitive tasks (ECTs) using chronometric techniques: (a) the S. Sternberg memory scan task, (b) a visual scan task which is perfectly analogous to the memory scan, except that the target digit is presented first and the subject must then scan a set of digits and indicate the presence or absence of the target digit in the set, and (c) the Hick paradigm, which involves responding to a visual stimulus (a light going “on”) when the stimulus is one among sets of either 1, 2, 4, or 8 equally probable alternatives. Certain parameters of all three tasks, such as intercept and slope of RT as a function of set size, from which different cognitive processes are inferred, are compared experimentally and correlationally. Subjects were 48 university students, tested and retested on the three tasks in a counterbalanced design on two separate days to obtain the retest reliabilities needed to correct all correlations for attenuation. Subjects were also given Raven's Advanced Progressive Matrices as a measure of psychometric g. Parameters of the ECTs are significantly and, in some cases, quite substantially correlated with g. Virtually all of this correlation is due to the general factor of the various ECTs, rather than to specific processing components (independent of the general factor). The results also indicate that different ECT paradigms (e.g., visual search and memory search tasks) may yield markedly different values in terms of the group means of analogous parameters, indicating different processes, and yet not show independence of the parameters in terms of individual differences; that is, measurements of the different parameters in individuals are perfectly correlated (i.e., disattenuated correlations do not differ significantly from r = 1). This is found for the intercept parameter of visual and memory search. The reverse condition is also found for the other parameters (e.g., slope); that is, their mean values are nearly identical, suggesting the same processes, yet disattenuated correlations between individual differences are relatively low, or even negative, indicating different processes. Although the general factor clearly predominates, it does not completely overwhelm individual differences in various component processes that are distinct from the general factor.