Lack of attentional control--inability to concentrate--has often made the difference between successful and unsuccessful performance on the part of athletes. Attention is controlled neurologically by a very complex interaction of a large portion of the cerebrum and is not localized to any one structure. The mechanism involves a memory retrieval process to judge the pertinence or meaning of stimulus inputs and thereby decide upon whether or not attention should be allocated to such inputs. Biofeedback technology suggests a way in which the attentional control mechanism could be optimized in the training of athletes. (Author/JD)