Effects of practice and distribution of auditory signals on absolute identification

In absolute identification of intensity, signals near the edges of the range being used are usually identified more accurately than those in the midrange. In one account, the extreme signals serve as anchors, and judgments are postulated to deteriorate as the distance from the signal to the nearest anchor increases. Our data suggest that, provided one corrects for the inherent asymmetry of errors for end and interior signals, the edge effect is rather smaller than it might first appear and is largely confined to the more intense edge. Moreover, anchors are not necessarily located at the edges of the range, but rather at the edges of the largest subset among which difficult discriminations are required. Further, this subset is not defined wholly by the signals used in a particular run, but by these together with those previously encountered in that day’s session. Neither practice nor payoffs appear to influence the location of the anchor so long as the discrimination requirements are maintained. Finally, the role of anchors is interpreted in terms of the differential location of an attention band which controls the sample size upon which the representation of the signal is based.