| Abstrakt: |
Two experiments examined the effect of the miscuing of an unconditioned stimulus on Pavlovian conditioned responding. In Experiment 1 (N = 32), subjects received 12 CS+-US and 12 CS− presentations followed, in the experimental group, by a CS−-US pairing (miscuing) on Trial 25 and a CS+US pairing on Trial 26. For the control group, Trial 25 consisted of a CS-alone presentation and Trial 26 consisted of a (CS+-US pairing. Visual stimuli (geometric shapes) of 8-s duration served as CSs, and a 1-s burst of white noise (100 dBA) was used as the US. Both electrodermal activity and a continuous measure of US expectancy were obtained. Expectancy of the US was significantly lower in the experimental group than in the control on the W-US trial which followed miscuing, whereas electrodermal responses to the US were significantly larger. However, first- and second-interval responses during cs+ on this trial were not influenced by miscuing. Experiment 2 (N = 64) employed the same stimuli and procedures as used in Experiment 1, but the dependent measure was reaction time to a probe stimulus presented either early (300 ms) or late (7500 ms) during some CSs+ and some CSs−. During the acquisition phase, probe reaction time was slower during CS+ than during CS regardless of probe position. Moreover, reaction time to probes presented during CS+ on the trial which followed miscuing was slower in the experimental group than in the control irrespective of probe position. Although not all findings were as predicted, the present results suggest that a CSUS pairing disrupted the association between CS+ and the US. This effect of US miscuing is difficult to interpret within the framework of current theories of Pavlovian Conditioning. [ABSTRACT FROM AUTHOR] |
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