Nine subjects, 5 of whom claimed absolute pitch (AP) ability (4 from childhood, 1 by self‐training) were given a pitch judgment task in which they had to strike notes on the piano as rapidly as possible to match randomized tape‐recorded piano notes. Stimulus set sizes were 64, 16, or 4 consecutive semitones, or 7 diatonic notes of a designated octave. A control task involved motor movements to notes announced in advance, with the effect that set size was 1. Accuracy, measured on the basis of deviations of responses from targets, significantly differentiated AP from NAP (non‐AP) subjects at all set sizes except the control task. For both groups, accuracy increased as set size decreased. Decision times, measured as that part of total response time before a movement to the response note began, decreased as set size decreased, but did not differentiate AP and NAP subjects. The performance of the trained AP subject was not distinguishable from that of the remaining AP subjects either in accuracy or decision time. Results are discussed in terms of a two‐factor theory of AP ability whereby NAP subjects use only relative tone height as the basis of judgment but AP subjects also use standards of tone chroma stored in long‐term memory. The abnormally high channel capacities and rates of information gain for AP subjects are interpreted on the basis of transmission of information in two channels, whereas NAP subjects transmit information in only one channel.