The effect of constant vs. varied encoding and massed vs. distributed presentations on recall of paired associates

The variables of coding (constant vs. varied) and spacing (massed vs. distributed) were factorially combined in an independent-groups design. Sixteen nominal pairs were presented twice, with the two presentations being either massed or distributed. A given nominal pair (e.g., AR-LE) was accompanied either by the same word-pair code on both presentations (e.g.,arm-leg) or by a different code on each presentation (e.g.,arm-leg; arrive-leave). On a subsequent recall test, the nominal stimulus only was shown. Better recall of the nominal response was found after constant coding and after distributed presentations, and there was no interaction between the spacing and coding variables. The results (a) support none of the current proposed explanations for the distributed practice effect, and (b) suggest that the critical factor in determining the probability of response recall is the strength of the strongest potential route to the response, not the number of different routes. This research was supported by a grant from the Graduate School of the University of Wisconsin.     

The assessment of discriminative encoding in memory for paired associates

A technique for providing for the measurement of encoding stability and intralist stimulus discrimination is presented and applied to the analysis of some paired-associate data. Essentially, the measure involves a recall test for all stimuli in the list except one, then presenting either a previously tested stimulus or the missing stimulus. Recognition of repeated stimuli reflects code stability, and recognition of the missing stimulus reflects stimulus discrimination.     

Two studies of visual search for word targets with controlled rates of presentation*

The two studies reported involve the visual search of word lists for a target item when the rate of presentation is controlled and the words are presented tachistoscopically. In the first study, the target is differentiated physically from the filler items by being capitalized. When the target is the last item in a list, it is readily identified at all presentation rates, but when it is the first word or is embedded in a list, recognition accuracy is inversely related to presentation rate. In the second study, the differentiation between target and filler items is in terms of the presence or absence of category membership. All Ss at all presentation rates do significantly better on lists with an animal word as a target and a set of unrelated words as filler items than on the converse arrangement.     

No evidence for a role of reconsolidation in updating of paired associates

Reconsolidation theory states that memories are labilized through reactivation, making them prone to change, before being re-consolidated. When information in memory requires updating, reconsolidation theory therefore predicts that reminders of previously learned information should facilitate updating of that information and should thus improve memory for the updated information. In two experiments, we tested this prediction by investigating memory for word pairs over a short time-scale. Participants studied word pairs (A–B), some of which were subsequently updated with word pairs that shared the first word (A–C). Half of the A–C pairs received a pre-study reminder of the first word in the pair so as to reactivate and labilize A–B memory. In a recognition memory test targeting the A–C list, reminders by and large had no effect on memory. Results thus failed to support the predictions of reconsolidation theory.     

Effects of varying the percentage of key illuminations paired with food in a positive automaintenance procedure

Three pigeons were exposed to a positive automaintenance procedure in which each trial began with a brief tone followed by the transillumination of a small central area of the response key for 10 sec. Key illumination was followed by food on 100%, 50%, 25%, 12.5%, and 0% of the trials. The effects depended on the dependent variable observed. The mean rate of responding during key illumination rapidly increased and then decreased slightly as the percentage of key illuminations paired with food increased. The number of key illuminations during which at least one response occurred increased as a negatively accelerating function of the percentage of key illuminations paired with food, and the mean latency to the first response during the key illuminations decreased as a negatively decelerating function of the percentage condition. The mean rate of sustained responding during key illumination was not systematically affected by changes in the percentage conditions.