Processing information about covariations that cannot be articulated.

Processing of covariation (among features) present in stimulus material was investigated. Subjects were unable to articulate the manipulated covariation between verbally described psychological characteristics and appearance of a set of stimulus persons. Based on the two-stage question answering model (Glucksberg & McCloskey, 1981), it was hypothesized that if the information related to the manipulated covariation was processed and registered, it would result in an increase of processing time for the questions that might be considered relevant to the covariation. The pattern of response latencies obtained in each of 3 experiments conformed exactly to the predictions. In 2 of these experiments, effects of the stimulus material on subjects' subsequent judgments were found, consistent with the model. Subjects behaved as if they had learned the rule (implied by the covariation) and followed it in their subsequent judgments. The demonstrated phenomenon pertains to an important and presumably ubiquitous aspect of processing categorical information. Research on suggests that people can process information about complex relations between elements of stimulus material without being able to articulate these relations. In a series of studies, Reber and his colleagues demonstrated that after being exposed to a number of items (strings of letters) generated by a set of specific rules (a grammar that specifies permissible orders of letters), people are able to use these rules (or information related somehow to these rules) in their subsequent judgments pertaining to whether novel items obey these rules, although the perceivers are not able to articulate the rules they use (Reber, 1967, 1976; Reber & Allen, 1978; Reber & Lewis, 1977). Reber concluded that such implicit and unconscious' learning is a natural product of attending to structured stimuli. Although the specific mechanism of implicit learning is far from being clear, these results indicate that people are able to process information about certain rules contained implicitly in stimulus material and to use these rules (or information related somehow to these rules) in their subsequent perceptions, and still be unable to articulate the rules (see also Brooks, 1978; Gordon & Holyoak, 1983). The research on implicit learning raises the question as to what kind of formal aspect or hidden structure contained in stimulus material is subject to such processing without a perceiver's being able to articulate what in particular is being processed. Recent research by Lewicki (1982, in press) suggests that one of these formal aspects might be the covariation among events