ABSTRACT
Hypotheses to explain the repetition effect in serial choice reaction tasks have suggested that on each consecutive trial S compares the percept of the current signal against his memory trace of the last. A direct test was made of this hypothesis, requiring Ss in a serial self-paced choice reaction time task to classify each signal as being the same or different from its predecessor. The results of three experiments show that the nature of successive judgments interferes with the selection of successive responses made to implement them. Reaction times are also affected by the nature of comparisons between successive signals. Repetitions of signals, repetitions of responses, and repetitions of judgment are all shown to contribute to sequential effects. The hypothesis of identity between processes underlying repetition effects and those underlying binary classification of successive signals is shown to be untenable, and, in view of the complexity of the interactions obtained, far too simple to be of use in interpreting experimental data. The nature of the interactions obtained raises difficulties for recent popular methodologies and for the decompositions of reaction time data obtained from these methodologies on the assumption of simple additivity of RTs of component processes to give overall observed RT.
