Procedural effects on performance on the Hick paradigm: Bias in reaction time and movement time parameters

This study investigated the effects that procedural variations may have on reaction time (RT) and movement time (MT) parameters from the Hick paradigm. Each of the 122 subjects was assigned to one of six experimental conditions. The six conditions represented the factorial crossing of two effects: (a) order of administration of bit conditions (ascending, random, and reversed), and (b) grouping of response alternatives (grouped and spread). The results revealed significant linear effects of order, and therefore of practice, on the slope relating both RT and MT to bits of information; corresponding effects on RT and MT intercept were in the predicted direction, but were nonsignificant. Visual attention effects were not found on any of the parameters; however, the difference in the slope relating MT to bits of information between grouped and spread response alternatives was interpreted as a response bias effect. Correlations between RT and MT slope parameters and Scholastic Aptitude Test scores supported the hypothesis that correlations between intelligence and RT and MT slope parameters derived from the Hick paradigm are a function of individual differences in practice effects, rather than individual differences in basic speed of information processing. Implications for research on the Hick paradigm are discussed.