Short-Term Visual Recognition Memory in Pigeons

Recognition memory for lists of items was investigated in pigeons using a YES-NO recognition technique. Experiment I showed that increasing the exposure duration of the first item of a two-item list improved recognition for that item without impairing recognition of the second item. Experiment II showed that decreasing the inter-trial interval had no effect on correct YES responses but significantly increased the number of false YES responses. Experiment III showed that recognition for the last two items of a three-item list was no poorer than that for lists of only two items. Experiment IV showed that increasing the delay between presentation and test of a two-item list (from 0·25-1 s) had a more disruptive effect on recognition for the second than for the first item. The data from these four experiments support a model proposed by Roberts and Grant, according to which memory traces are independent, and decay as a negatively accelerated function of time. Experiments V, VI, and VII investigated recognition for lists of three, four, and five items, and found no evidence for a primacy effect, performance being a linear function of time since sample offset.