Cumulative proactive interference in animal memory

Events occurring on the prior trial in delayed matching-to-sample tasks can proactively interfere with accurate matching on the current trial. The present study investigated the accumulation of proactive interference in delayed matching-to-sample at the local level of two consecutive trials, as well as in terms of a general performance decrement accumulating over the session. Higher-order analyses, in terms of the parameters of negative exponential functions fitted to the data, showed that the magnitude of the local proactive-interference effect resulting from inter-trial disagreement of stimuli decreased over the session. Furthermore, there was no evidence for the general performance decrement over the session, which is frequently attributed to proactive interference. The attenuation of the local proactive-interference effect was accounted for in terms of changes in the relative probabilities of agreeing and nonagreeing trials.