Effects of interpolating a secondary task during the intertrial interval of a concept identification problem

Several tasks were interpolated during the intertrial interval (ITI) of a concept identification (CI) task. In Experiment I, 234 subjects were required to count backwards by threes, emit a sibilant, or to refrain from thinking after all responses, after correct responses, or after errors. Counting backwards interfered with performance, but only if it occurred after errors. Stimulus and feedback information was either withheld, as in Experiment I, or made available during the ITI in Experiment II. Results of the data from 280 subjects indicated that counting backwards interfered with performance only when interpolated after errors, when stimulus-feedback information was withheld, but had an equivalent effect after errors and correct responses when stimulus-feedback information was available during ITI, indicating that different strategies were induced by the presence of such information.