The relationships between feedback, its source, and the increases or decreases of the behavior associated with it were investigated to apply predictions of the credibility gap regarding the effects of feedback on the acquisition of an individual skill. Subjects (N=45) were randomly assigned to one of five treatment conditions and provided different types of feedback based on their actual task performances on two different trials. Dependent variables selected to measure the effect of the experiment included state-anxiety, self-confidence, credibility and desirability of feedback, and qualitative ratings for each subject's responses. Results indicated that positive feedback is almost always rated as more credible by recipients, and that subjects, while more receptive to positive feedback and tending to ward off negative feedback, acquire the performance task regardless of the feedback received. (Author/HLM)