A limited-capacity response process in absolute identification

In two absolute identification experiments, the dependency of the current response, Rn, on the immediately preceding stimulus, Sn-1, and response, Rn-1, was measured by means of multivariate information transmission (see McGill, 1954). In these experiments, the amount of stimulus information available to subjects, measured as the amount of information transmission from a current stimulus, Sn, to Rn, was manipulated. The magnitude of the dependency of Rn on Sn-1 and Rn-1 was inversely proportional to that of information transmission from Sn to Rn, supporting the argument of Ward and Lockhead (1971) that the less stimulus information the subjects get, the more their responses will be likely to depend on previous stimuli and responses. Interestingly, the sum of information transmission from Sn, Sn-1, and Rn-1 to Rn was always about 2.5 bits, without respect to the variance of each term. This result could have arisen from the operation of a limited-capacity response process.