What causes the spacing effect? Some effects of repetition,duration, and spacing on memory for pictures

Three experiments examined effects of the spacing of repetitions on memory for pictures. In Experiment I, the duration of the first presentation (P(1)) was manipulated, as was P(1)-P(2) spacing. The effect of spacing on judged frequency was independent of P(1) duration. In Experiment II, pictures were given M massed presentations just prior to the P(M)-P(M+1) spacing interval. The form of the spacing curve was independent of M. Neither experiment confirmed the prediction of "overhabituation," derived from the habituation-recovery explanation of the spacing effect. In Experiment III, subjects made both duration and frequency judgments. The duration judgment results were not consistent with the notion that subjects remember multiple massed presentations as single occurrences of especially long duration. Some evidence from Experiments I and III suggests that an interrupted stimulus is recognized better than one that is not interrupted-a finding that, if replicable, would support the habituation-recovery account of the spacing effect.     

Voluntary attention and the spacing effect

Three experiments were done to test the hypothesis that the spacing effect results from a voluntary decision by the subject to pay little attention to the second presentation (P₂) of an item when it occurs shortly after the first (P¹)- In all three experiments, the spacing of repetitions was varied. In Experiment I, allocation of attention was manipulated by pairing P₂ of some pictures with a signal that indicated high payoff for later retention. In Experiment II, attention was controlled more directly by requiring the subject, in one condition, to recite words aloud. In both experiments, the dependent variable was judged frequency. In neither experiment did the effect of the attention manipulation interact with that of the spacing of repetitions. In Experiment III, the number of eye fixations given a picture was taken to be a measure of attention. The number of fixations dropped from P₁ to P₂ to P₃, but was unaffected by the spacing of repetitions. The experiments provide no support for a voluntary attention explanation of the spacing effect.     

Temporal aspects of selective masking

In two experiments, rows of random letter sequences were presented for 100 ms and were patterned masked at varying delays after display offset. In Experiment I recall was probed by visual partial report cues, while auditory probes were employed in Experiment II. Compared to no-masking control conditions, the masking stimulus had a selective effect at the different positions of the rows. The masking stimulus produced the largest decrements in recall of letters from the centre positions of the displays but had a minimal effect on performance at either end of the rows. Furthermore, it was demonstrated that improvements in recall were limited to the centre positions of the rows at increased delays of mask. Subsidiary analyses revealed that processing of the end letters of the displays terminates shortly after display offset while processing of the centre letters continues for at least 500 ms. The results are consistent with the notion that processing of multi-letter arrays commences at the ends of the rows and that the selective masking effect reflects the order of processing of the contents of iconic memory. However, these results were evident only in Experiment II which employed auditory partial report cues. When the partial report cues were visual, there were no effects of masking and minimal increases in performance at increased delays of mask. The discrepant results of the two experiments are discussed in terms of process interruption caused by obligatory attention to the partial report cues.     

Subproblem analysis of discrimination shift learning

Although attention models assume that the two subproblems of a discrimination shift are treated as a single problem, learning of a nonreversal shift can be broken down into performance on the subproblem that changes reward conditions and the one that does not. A general analysis of performance on these subproblems, appropriate to a broad range of attention models, is developed in this paper. This analysis leads to a rejection of attention models for some S populations, but shows that attention models may have been rejected prematurely for other populations of Ss.     

COOPERATION,COMPETITION AND ALTRUISM AMONG SCHOOLCHILDREN IN ZAMBIA

Partant de l'hypothèse que l'Africain traditionnel est plus coopératif que l'Européen ou le Nord-Américain — la société occidentale orientant vers des conduites compétitives — l'auteur propose à quarante garçons zambiens et quarante garçons blancs le jeu du Dilemme du Prisonnier et un second jeu où chaque enfant possède le contrôle total du gain relatif apparent de son adversaire. Le plan expérimental de type factoriel 2×2× utilise les variables suivantes : groupe ethnico-racial du sujet, groupe ethnico-racial de l'adversaire ainsi que deux niveaux d'apparente coopération de l'opposant. Aucun des effets principaux ni des interactions ne fut significatif. La variance des groupes zambiens apparut significativement plus grande que celle des groupes américains-européens dans le jeu du Dilemme du Prisonnier et surtout dans le cas d'un partenaire coopératif. l'esprit de compétition s'avéra très élevé dans tous les groupes et des expériences complémentaires ne purent révéler beaucoup d'altruisme.     

Administration of inhalation anesthetics to small animals: Some problems and solutions

Some problems inherent in administering inhalation anesthetics to small laboratory animals in studies of memory consolidation are discussed. A simple and inexpensive apparatus which has been designed to eliminate some of these problems is described.     

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.     

Rapid response and flexible experimental control with a small on-line computer: PSYCLE

This is an outline of some solutions to problems in using a relatively slow computer, without expensive peripheral apparatus, for control of psychoacoustic experiments. Major concerns were accurate timing and the ability to change from one experiment to another without extended reading of programs from paper tape.     

Comparison of intrusion errors and serial position curves on monaural and dichotic listening tasks: A developmental analysis

Based on a repeated measurement study of 7-, 10-, 14-, and 17-year-olds with monaural and dichotic presentations of word lists varying in associative structure and presentation rate, intrusion and serial position dependent variables were analyzed. Intrusion analyses supported previous reports on word list recall; vis, 7- and 10-year-olds recalled fewer words from monaural and dichotic lists and had more intrusive errors than adolescents. Based on similar orders of report (strategies) for monaural and dichotic word presentations, serial position curves for the two types of presentation were compared. Within-age comparisons were strikingly similar. Between-age comparisons of monaural and dichotic presentation serial position curves support the notion that there are ontogenetic limitations in memory structure and control processes.