Eyelid response topography in differential interstimulus interval conditioning.
The problem of conditioned eyelid discrimination was investigated with a differential interstimulus interval (ISI) conditioning procedure. In two groups, conditioned stimulus (CS) lights presented in the left or right visual fields signaled ISIs of 800 or 1,200 msec before delivery of an airpuff unconditioned stimulus. Two additional groups received one or the other ISI with both CSs. Somewhat unexpectedly, none of the response-frequency or topography measures showed evidence of conditioned discrimination in the differential ISI groups. Instead, the latencies and puff-attenuating topographies of responses were much more appropriate to the ISI given on the preceding trial, n--1, than to the ISI cued on trial n. Neither the absence of conditioned discrimination nor the presence of ISI sequential effects was related to subjects' reported awareness of the CS-ISI contingencies, suggesting that the overriding process was a relatively "automatic" shaping and reshaping of responses in accord with recent ISI experience. These results are discussed in terms of the complex stimulus- and response-processing requirements of the task. Across all four groups there was some evidence of a relative excitatory response bias to CSs presented in the right visual field, and it was found that voluntary-form responders (but not conditioned-form responders) initially gave more alpha responses to the right-field CS than to the left-field CS. These results were examined for possible hemispheric processing implications.