Stimulus-response compatibility effects have been shown to persist even after extended practice. In the present study, two experiments were conducted to see if the effects persist when knowledge of results that allows subjects to set performance goals is provided. In the first experiment, summary feedback about mean accuracy and mean reaction time was provided after each block of 40 trials of practice in a two-choice spatial compatibility task. Subjects practiced the task for 2,400 trials, yet the compatibility effect was not eliminated. Compared to previous experiments, reaction times were faster overall, but the degree of change was the same for both compatible and incompatible assignments. In the second experiment, a response deadline was imposed on each trial. If the subject did not respond within the time limit, which was reduced as the experiment progressed, auditory feedback was presented. Summary feedback was also presented as in Experiment 1. Again, 2,400 trials of practice reduced but did not eliminate the compatibility effect. The greater reduction in the difference in reaction times for compatible and incompatible assignments, relative to other experiments, could be attributed to speed-accuracy tradeoff. The results indicate that the persistence of stimulus-response compatibility effects with extended practice is not due to poorer motivation to perform with the incompatible assignment. The results suggest that training will be insufficient to overcome difficulties in performance resulting from spatially incompatible assignments.
