Restoration of stimulus associability, electrodermal activity, and processing resource allocation.

Four experiments investigated Pearce and Hall's (1980) proposal that a decrease in the predictive accuracy of a stimulus restores stimulus associability as reflected by increased orienting and controlled processing. The experiments examined the effects of miscuing or omission on stimulus associability as assessed by stimulus expectancy, electrodermal responding, and reaction time (RT) to a secondary task probe stimulus. In Experiments 1 and 2, a control group received 21 S1-S2 trials intermixed with 21 S3-alone presentations. For the experimental group, S2 was miscued by its presentation following S3 on two trials. In Experiments 1 and 2a, S1, S2, and S3 were moderate intensity stimuli, but in Experiment 2b, shock was used as S2. Experiment 1 (N = 24) demonstrated that, although there was uncertainty about whether S2 would follow S3 when S3 was re-presented following miscuing, skin conductance responses to S3 did not differ according to whether or not it had miscued the previous S2. Experiment 2a (N = 48) and Experiment 2b (N = 24) demonstrated that RT to white noise probe stimuli presented during the S3-alone presentation immediately following miscuing did not differ between experimental (miscuing) and control (no miscuing) groups. In Experiments 3 and 4, a control group received 23 S1-S2 trials. For the experimental group, S2 was omitted on two trials. In Experiment 3 (N = 24) S1 and S2 were of moderate intensity, whereas in Experiment 4 (N = 24) shock was used as S2. Reaction time to white noise probes presented during S1 did not differ according to whether or not the previous S2 was omitted. Thus, despite evidence of a reduction in the predictive accuracy of both S3 following miscuing and S1 following omission, there was no evidence of restoration of the associability of either S1 or S3. The results are discussed in terms of current theories of associative learning.