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.     

Detrimental influence of contextual change on spacing effects in free recall

Two experiments were conducted to determine the mechanism underlying the spacing effect in free-recall tasks. Participants were required to study a list containing once-presented words as well as massed and spaced repetitions. In both experiments, presentation background at repetition was manipulated. The results of Experiment 1 demonstrated that free recall was higher for massed items repeated in a different context than for massed items repeated in the same context, whereas free recall for spaced items was higher when repeated in the same context. Furthermore, a spacing effect was shown for words repeated in the same context, whereas an attenuated spacing effect was revealed for words repeated in a different context. These findings were replicated in Experiment 2 under a different presentation background manipulation. Both experiments seem to be most consistent with a model that combines the contextual variability and the study-phase retrieval mechanism to account for the spacing effect in free-recall tasks.     

Surface form and the spacing effect

Deficient processing theories of the spacing effect attribute poor recall of massed-repeated items to a failure to process one or both of the presentations fully. An implication of this approach is that anything that increases the probability that a repetition will receive full processing, or conversely, anything that decreases the probability that the item will be recognized as a repetition, should improve memorability of the item. The present set of experiments tested this prediction by manipulating the surface structure of repeated sentences. On the basis of previous research, it was assumed that memory for surface structure of sentences decays rapidly, and hence can contribute to initial identification of repetitions only at short spacings. Because this manipulation should hinder recognition of repetitions as repetitions, it was expected to induce full processing of massed repetitions, and thus facilitate recall of these items. This prediction was supported. When sentences were repeated verbatim (Experiment 1) or by the same speaker (Experiment 2), the typical spacing effect was obtained. However, when the surface structure or speaker changed at time of repetition, massed repetitions were recalled nearly as well (Experiment 1) or as well (Experiment 2) as their spaced counterparts.     

Spacing enhances the learning of natural concepts: an investigation of mechanisms,metacognition, and aging

In two experiments, we examined spacing effects on the learning of bird families and metacognitive assessments of such learning. Results revealed that spacing enhanced learning beyond massed study. These effects were increased by presenting birds in pairs so as to highlight differences among families during study (Experiment 1). Self-allocated study time provided evidence that more attention was paid during spaced than during massed study and resulted in no age differences in learning (Experiment 2). Metacognitive measures revealed sensitivity to the processing advantage of spaced study and to differences in classification difficulty across categories. No difference occurred in monitoring accuracy for young versus older adults. These findings provide evidence for discrimination- and attention-based accounts of the spacing effect in natural concept learning.     

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.     

Spacing repetitions over 1 week

Does varying the spacing of repetitions over intervals as long as 1 week aftect recall? The answer from three experiments is yes. Subjects incidentally processed words repeated within a single list and words repeated in separate lists at list spacings of up to 1 week. Memory was tested by free recall shortly after the second presentations or after retention intervals of up to 1 week. Recall of the words repeated across separate lists conformed to a proportionality rule. When the retention interval is short relative to the spacing intervals, performance is inversely related to spacing. When the retention interval is a large proportion of the spacing intervals, performance is directly related to spacing. Does varying the spacing of repetitions within a single list affect recall after a retention interval of 2 weeks? The answer depends on the processing used while studying the words. Processing that generated interitem associations resulted in a within-list spacing effect even after a 2-week retention interval. Without the interitem associations, the effect was absent after a 1-day retention interval. Most of these findings were explained by examining the changing relationship between the retrieval context and the context stored during study.     

Adult age differences in memory for massed and distributed repeated actions

Adult age differences in memory for actions were investigated in 2 experiments in which actions were repeated with massed or distributed spacing. In Experiment 1, subjects received a mixed series of actions, half performed once, the others twice, with repetitions either massed or distributed. Young subjects recalled more actions than did the elderly, and more distributed actions were recalled than massed actions. However, the Age X Spacing interaction was not significant. A probable inhibitory mechanism with a mixed list was avoided in Experiment 2 by use of unmixed series. Actions were performed once only, twice only in massed repetitions, or twice only in distributed repetitions. The age difference was significant, and more actions were recalled in the distributed condition than in either of the other conditions, the results of which did not differ from one another. The Age X Conditions interaction was negligible. These results imply that elderly subjects are as likely as young subjects to encode contextual information while performing actions.     

Implicit word activation during pre-recognition processing influences correct recognition and estimates of presentation frequency

False recognition of new test words is higher for experimental lures (e.g., universal) with initial phonemes identical to studied words (e.g., university) than for control lures. A proposed mechanism to explain this phenomenon involves implicit activation of potential solution words during the brief period of uncertainty immediately following onset of a spoken study word. Two experiments examined whether the presumed pre-recognition processing during the stimulus discovery phase of spoken word identification increased familiarity of a studied word, thereby increasing correct recognitions and estimates of presentation frequency. Critical test words were presented a single time during study in Experiment 1, and their phonologically related words were presented one, two, or three times. Correct recognition and frequency estimates of targets were enhanced by multiple presentations of associates sharing initial phonemes. Experiment 2 provided a replication with five repetitions of phonological associates during study and two study presentations of critical test words. The results of these two experiments confirmed a necessary theoretical consequence of the implicit activation mechanism that has been invoked to explain the effects of phonological similarity on false recognition.     

The spacing effect in 4- to 9-year-old children

Experiment 1 of the current research failed to replicate Toppino and Di George’s (1984) finding that older children but not preschoolers showed a spacing effect. Instead, we obtained the spacing effect in all the age groups tested (preschool, kindergarten, first-grade, and third-grade children). The effect was demonstrated with two types of material, words and pictures. Experiment 2 focused on the role that very brief spacings, with no intervening items between repetitions, play in later retention. Age groups and materials were the same as in Experiment 1. Four different levels of spacing were included (0-, 1.1-,2.5-, and 5-sec intervals). The spacing effect was again obtained for all age groups with both words and pictures. The results of both experiments suggest that the spacing effect does not emerge with development.     

The relationship between repetition and depth of processing

The relationship between depth of information processing and stimulus repetitions was investigated using a simultaneous category judgment task. Several levels of processing were defined involving (1) physically identical items, (2) physically different but same-name items, (3) different items from the same semantic category, and (4) items from different categories. Stimulus pairs were represented by words and pictures, and each pair was presented one, three, or five times. Response times for categorization judgments increased with the level of processing and decreased with repetitions. Repetitions produced greater facilitation for decisions at deeper levels of processing. In a final incidental recall task, more items were remembered from category-same trials than from same-item trials, but level of processing did not interact with number of presentations. Repetitions produced an equivalent increase in final recall probability for items involved in all decision types, indicating that distributed repetitions can lead to the formation of stronger memory traces at several levels of processing.     

Implicit word activation during pre‐recognition processing influences correct recognition and estimates of presentation frequency

False recognition of new test words is higher for experimental lures (e.g., universal) with initial phonemes identical to studied words (e.g., university) than for control lures. A proposed mechanism to explain this phenomenon involves implicit activation of potential solution words during the brief period of uncertainty immediately following onset of a spoken study word. Two experiments examined whether the presumed pre‐recognition processing during the stimulus discovery phase of spoken word identification increased familiarity of a studied word, thereby increasing correct recognitions and estimates of presentation frequency. Critical test words were presented a single time during study in Experiment 1, and their phonologically related words were presented one, two, or three times. Correct recognition and frequency estimates of targets were enhanced by multiple presentations of associates sharing initial phonemes. Experiment 2 provided a replication with five repetitions of phonological associates during study and two study presentations of critical test words. The results of these two experiments confirmed a necessary theoretical consequence of the implicit activation mechanism that has been invoked to explain the effects of phonological similarity on false recognition.     

Lexical processing and text integration of function and content words: Evidence from priming and eye fixations

The results of two experiments comparing processing of function words and content words are reported. In Experiment 1, priming was present for both related function and related content word pairs, as measured in lexical decision response times. In Experiment 2, participants' eye movements were monitored as they read sentences containing either a high- or a low-frequency function or content target word. Average word length and word frequency were matched across the function and content word conditions. Function words showed frequency effects in first-fixation and gaze duration that were similar to those seen for content words. Clear differences in on-line processing of function and content words emerged in later processing measures. These differences were reflected in reading patterns and reading time measures. There was inflated processing time in the phrase immediately following a low-frequency function word, and participants made more regressions to the target word in this condition than in the other three conditions. The priming effects in lexical decision and the word frequency effects in initial processing measures in silent reading for both word types were taken as evidence of common lexical processing for function and content words. The observed differences in later processing measures in the eye-movement data were taken as evidence of differences in the role that the two word types have in sentence processing beyond the lexical level.     

The effect of identical word pairs on people's metamemory judgments: What are the contributions of processing fluency and beliefs about memory?

Judgments of learning (JOLs) are higher for identical pairs (dog–dog) than for related pairs (dog–cat). This identical effect may be mediated (a) by processing fluency (i.e., identical pairs are processed faster than related pairs) or (b) by a belief that identical pairs are better remembered or (c) by both factors. In the present work, we assessed the contribution of both factors. We evaluated whether a measure of processing fluency (i.e., self-paced study) mediated the relationship between pair type and JOLs (Experiment 1) and attempted to disrupt processing fluency using an AlTeRnAtInG presentation format (Experiment 2). We also evaluated whether judgments made in the absence of processing fluency demonstrated the identical effect (Experiment 3), and, finally, we had participants read a vignette about an experiment that included both pair types and estimate which pairs would be best remembered (Experiment 4). Evidence from all experiments converged on the conclusion that people's beliefs about how variables affect memory—and not differential fluency—best explain the identical effect, although we cannot entirely rule out the possibility that fluency plays a small role. The outcomes were consistent with the analytic-processing theory of JOLs—namely, when instructed to make JOLs, people adopt an analytic problem-solving approach that involves identifying variation across pairs that plausibly relate to memory and then use this variation to make JOLs.     

Memory for frequency of bizarre and common stimuli: limitations of the automaticity hypothesis

In 2 experiments, the influence of intention to process frequency on accuracy of memory for frequency of bizarre and common sentences was investigated. The results from multiple regression analyses indicated that intentional processing increased the accuracy of frequency judgments when memory for frequency was tested after a 2-min (Experiment 1) and after a 48-hr (Experiment 2) retention interval. Furthermore, the results of Experiment 2 indicated that unintentional processors tended to overestimate frequencies of bizarre relative to common items after a delay. The implications of the results are discussed with regard to L. Hasher and R. T. Zacks's (1984) automaticity hypothesis, human performance, and the accuracy of judgments of frequency of occurrence of unusual events.     

What is the role of affect in the spacing effect?

In Experiments 1 and 2, after studying a list containing connotatively neutral words that were presented once or were presented at various spacing intervals, subjects either attempted free recall or made affective judgments of the study-list targets along a pleasant/unpleasant dimension. Spacing effects occurred in recall, and massed items were judged to be more unpleasantthan once-presented and spaced words. In the third experiment, subjects studied homogeneous lists composed of either connotatively good words or connotativelybad ones. Spacing effects were absent in the recall of both types of words because massed-practice words were recalled at a high level, one that was about the same as that for spaced-practice words. Affective judgments were unrelated to presentation condition, and both good and bad massed words were judged to be positive in affect. Although the data suggest that different study conditions can lead to different affective reactions, the results are moot with regard to the relationship between affect and the magnitude of spacing effects.     

The spacing effect in the learning of word pairs

Following the presentation of a single list of word pairs consisting of a three-letter word on the left and a five-letter word on the right, groups of 64 Ss each were asked to recall the (a) three-letter words, (b) five-letter words, (c) intact pairs, or (d) five-letter words with the three-letter words provided. Two types of repeated pairs were presented, one in which the same three- and five-letter words were repeated together (same pairs) and one in which the same five-letter word was repeated with different three-letter words (different pairs). For half of the Ss in each recall group, the repetitions of a pair containing a given five-letter word were massed (MP); for the other half, the repetitions were distributed (DP). Recall of MP same pairs and the eomponents of these pairs was consistently poorer than that of DP same pairs. Recall of the repeated component of the different pairs was also poorer under MP than under DP. The results were interpreted as supportive of an attenuation-of-attention explanation of the spacing effect.     

Encoding variability,levels of processing,and the effects of spacing of repetitions upon judgments of frequency

Two experiments were carried out to compare the component-levels theory and the levels-of-processing hypothesis as explanations of the effect the spacing between repetitions of an item has upon the retention of that item. Retention was measured by judgments of frequency, frequency discrimination, and derived recognition scores. Variable encoding contexts facilitated recognition relative to repeated encoding contexts, while the latter biased subjects toward giving high judgments of frequency. The results in general were consonant with predictions derived from a levels-of-processing explanation of the spacing effect rather than the component-levels theory. A modification of the latter theory to incorporate the former was suggested as a view of the memorial representation of repeated stimuli.     

Picture-word differences in decision latency: a test of common-coding assumptions

Three experiments examined the processing of pictures and words in two tasks of semantic decision--judgments of conceptual size and judgments of associative relatedness--in order to test the prediction from single-coding models of memory that different semantic decisions produce comparable picture-word latency differences. In Experiment 1 an interaction in decision latency was found such that picture-picture (P-P) pairs were significantly faster than word-word (W-W) pairs in decisions of size but not in decisions of associative relatedness. In Experiment 2 no latency differences were found in decisions of association for pairs presented in P-P, W-W, or mixed (P-W or W-P) forms. Decisions of size, however, were fastest for P-P pairs, intermediate for mixed pairs, and slowest for W-W pairs. In a third experiment, using a speeded inference task, the interaction obtained in the first two experiments was reproduced. In light of these results possible revisions to common-coding assumptions about the processing of pictures and words in semantic decisions are discussed.     

Spreading the words: A spacing effect in vocabulary learning

The spacing effect refers to the frequently observed finding that distributing learning across time leads to better retention than massing it into one single study session. In the present study, we examined whether the spacing effect generalises to primary school vocabulary learning. To this aim, children from Grade 3 were taught the meaning of 15 new words using a massed procedure and 15 other new words using a spaced procedure. The 15 words in the massed condition were divided into three sets of five words, and each set was taught three times in one of three learning sessions. In the spaced condition, learning was distributed across the three sessions: All 15 words were practised once in each of the three learning sessions. At the retention tests after 1 week and after 5 weeks we observed that the meaning of spaced words was remembered better than the meaning of massed words.     

Memory for Frequency of Bizarre and Common Stimuli: Limitations of the Automaticity Hypothesis

In 2 experiments, the influence of intention to process frequency on accuracy of memory for frequency of bizarre and common sentences was investigated. The results from multiple regression analyses indicated that intentional processing increased the accuracy of frequency judgments when memory for frequency was tested after a 2-min (Experiment 1) and after a 48-hr (Experiment 2) retention interval. Furthermore, the results of Experiment 2 indicated that unintentional processors tended to overestimate frequencies of bizarre relative to common items after a delay. The implications of the results are discussed with regard to L. Hasher and R. T. Zacks's (1984) automaticity hypothesis, human performance, and the accuracy of judgments of frequency of occurrence of unusual events.