A critical reappraisal of the evidence for unconscious abstraction of deterministic rules in complex experimental situations

In a recent experiment (Lewicki et al., 1988) subjects were submitted to a four-choice RT paradigm for 3600 trials. On each of the successive logical blocks of five trials, the first two locations of the target were randomly distributed, and the last three locations were determined by complex rules. Although subjects were unable to verbalize the actual nature of the manipulation, performance on the last trials of each block improved at a faster rate and was better overall than performance on the first trials. In addition, subsequent rules changes on 480 additional trials only affected performance on the last three trials of each block. The present paper demonstrates that contrary to Lewicki et al’s assertions this performance pattern requires neither acquisition of tacit knowledge of the composition rules, nor partitioning by the subjects of the sequence into logical blocks of five trials. Rather, the results can be accounted for by the relative frequency of a few simple sequences of target locations. Moreover, this alternative explanation alone correctly anticipates some striking features of tine-grained performance (Lewicki et al., 1988). The discussion focuses on methodological implications of these findings for investigation of unconscious learning, and speculates on what and how people learn when they encounter a complex and structured situation.