Peter P. J. L. Verkoeijen

Spacing and Testing Effects: A Deeply Critical, Lengthy, and At Times Discursive Review of the Literature

Abstract What appears to be a simple pattern of results—distributed-study opportunities usually produce better memory than massed-study opportunities—turns out to be quite complicated. Many “impostor” effects such as rehearsal borrowing, strategy changes during study, recency effects, and item skipping complicate the interpretation of spacing experiments. We suggest some best practices for future experiments that diverge from the typical spacing experiments in the literature. Next, we outline the major theories that have been advanced to account for spacing studies while highlighting the critical experimental evidence that a theory of spacing must explain. We then propose a tentative verbal theory based on the SAM/REM model that utilizes contextual variability and study-phase retrieval to explain the major findings, as well as predict some novel results. Next, we outline the major phenomena supporting testing as superior to restudy on long-term retention tests, and review theories of the testing phenomenon, along with some possible boundary conditions. Finally, we suggest some ways that spacing and testing can be integrated into the classroom, and ask to what extent educators already capitalize on these phenomena. Along the way, we present several new experiments that shed light on various facets of the spacing and testing effects.

Registered Replication Report

Trying to remember something now typically improves your ability to remember it later. However, after watching a video of a simulated bank robbery, participants who verbally described the robber were 25% worse at identifying the robber in a lineup than were participants who instead listed U.S. states and capitals—this has been termed the “verbal overshadowing” effect (Schooler & Engstler-Schooler, 1990). More recent studies suggested that this effect might be substantially smaller than first reported. Given uncertainty about the effect size, the influence of this finding in the memory literature, and its practical importance for police procedures, we conducted two collections of preregistered direct replications (RRR1 and RRR2) that differed only in the order of the description task and a filler task. In RRR1, when the description task immediately followed the robbery, participants who provided a description were 4% less likely to select the robber than were those in the control condition. In RRR2, when the description was delayed by 20 min, they were 16% less likely to select the robber. These findings reveal a robust verbal overshadowing effect that is strongly influenced by the relative timing of the tasks. The discussion considers further implications of these replications for our understanding of verbal overshadowing.

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.

Case representation by medical experts, intermediates and novices for laboratory data presented with or without a clinical context

Background  Based on cognitive psychological research, a number of theoretical frameworks have been put forward to describe the structure of experts’ medical knowledge and to explain experts’ case‐processing.

Learning Adinkra symbols: The effect of testing

The testing effect (i.e., long-term memory is improved more by intermediate testing than by restudying the information) has been studied using a variety of materials. However, almost all testing effect studies to date have used purely verbal materials such as word pairs, facts and prose passages. The testing effect has not yet been established using symbol–word pairs. In the present study symbol–word pairs were used as to-be-learned materials to demonstrate the generalisability of the testing effect to symbol learning. The results showed that there was no difference in final memory-test performance after a retention interval of 5 minutes, but after a retention interval of a week tested pairs were retained better than repeatedly studied pairs. Hence, the present research suggests that the testing effect can also be obtained in symbol learning.

Registered Replication Report : Rand, Greene, and Nowak (2012)

In an anonymous 4-person economic game, participants contributed more money to a common project (i.e., cooperated) when required to decide quickly than when forced to delay their decision (Rand, Greene & Nowak, 2012), a pattern consistent with the social heuristics hypothesis proposed by Rand and colleagues. The results of studies using time pressure have been mixed, with some replication attempts observing similar patterns (e.g., Rand et al., 2014) and others observing null effects (e.g., Tinghög et al., 2013; Verkoeijen & Bouwmeester, 2014). This Registered Replication Report (RRR) assessed the size and variability of the effect of time pressure on cooperative decisions by combining 21 separate, preregistered replications of the critical conditions from Study 7 of the original article (Rand et al., 2012). The primary planned analysis used data from all participants who were randomly assigned to conditions and who met the protocol inclusion criteria (an intent-to-treat approach that included the 65.9% of participants in the time-pressure condition and 7.5% in the forced-delay condition who did not adhere to the time constraints), and we observed a difference in contributions of −0.37 percentage points compared with an 8.6 percentage point difference calculated from the original data. Analyzing the data as the original article did, including data only for participants who complied with the time constraints, the RRR observed a 10.37 percentage point difference in contributions compared with a 15.31 percentage point difference in the original study. In combination, the results of the intent-to-treat analysis and the compliant-only analysis are consistent with the presence of selection biases and the absence of a causal effect of time pressure on cooperation.

Limitations to the spacing effect: demonstration of an inverted u-shaped relationship between interrepetition spacing and free recall.

The spacing effect refers to the finding that memory for repeated items improves when the interrepetition interval increases. To explain the spacing effect in free-recall tasks, a two-factor model has been put forward that combines mechanisms of contextual variability and study-phase retrieval (e.g., Raaijmakers, 2003; Verkoeijen, Rikers, & Schmidt, 2004). An important, yet untested, implication of this model is that free recall of repetitions should follow an inverted u-shaped relationship with interrepetition spacing. To demonstrate the suggested relationship an experiment was conducted. Participants studied a word list, consisting of items repeated at different interrepetition intervals, either under incidental or under intentional learn instructions. Subsequently, participants received a free-recall test. The results revealed an inverted u-shaped relationship between free recall and interrepetition spacing in both the incidental-learning condition and the intentional-learning condition. Moreover, for intentionally learned repetitions, the maximum free-recall performance was located at a longer interrepetition interval than for incidentally learned repetitions. These findings are interpreted in terms of the two-factor model of spacing effects in free-recall tasks.

Registered replication report: Rand, Greene, & Nowak

In an anonymous 4-person economic game, participants contributed more money to a common project (i.e., cooperated) when required to decide quickly than when forced to delay their decision (Rand, Greene & Nowak, 2012), a pattern consistent with the social heuristics hypothesis proposed by Rand and colleagues. The results of studies using time pressure have been mixed, with some replication attempts observing similar patterns (e.g., Rand et al., 2014) and others observing null effects (e.g., Tinghög et al., 2013; Verkoeijen & Bouwmeester, 2014). This Registered Replication Report (RRR) assessed the size and variability of the effect of time pressure on cooperative decisions by combining 21 separate, preregistered replications of the critical conditions from Study 7 of the original article (Rand et al., 2012). The primary planned analysis used data from all participants who were randomly assigned to conditions and who met the protocol inclusion criteria (an intent-to-treat approach that included the 65.9% of participants in the time-pressure condition and 7.5% in the forced-delay condition who did not adhere to the time constraints), and we observed a difference in contributions of −0.37 percentage points compared with an 8.6 percentage point difference calculated from the original data. Analyzing the data as the original article did, including data only for participants who complied with the time constraints, the RRR observed a 10.37 percentage point difference in contributions compared with a 15.31 percentage point difference in the original study. In combination, the results of the intent-to-treat analysis and the compliant-only analysis are consistent with the presence of selection biases and the absence of a causal effect of time pressure on cooperation.

Comparing the Effects of Testing and Restudying on Recollection in Recognition Memory

Recently, Chan and McDermott (2007) found that relative to studying words once, taking an initial test increased recollection, whereas it did not affect familiarity. However, an open question remains what the effect is of testing on recollection and familiarity relative to restudying. We conducted four experiments to address this question. Experiment 1 was a replication of Chan and McDermotts third experiment. In Experiment 2, restudied words were compared with tested words. In Experiment 3 we replicated Experiment 2 with the exception that feedback was provided after each initial-test trial. Finally, in Experiment 4, stronger cues were used during the initial test without feedback. The results showed a recollection advantage of testing over restudying, but only when feedback was given during the test or when stronger cues were employed. Further, recognition decisions were more familiarity based for restudied words than for tested words.

Latent variable modeling of cognitive processes in true and false recognition of words: A developmental perspective.

The present study aimed at testing theoretical predictions of the fuzzy-trace theory about true and false recognition. The effects of semantic relatedness and study opportunity on true and false recognition of words from Deese, Roediger, McDermott lists (J. Deese, 1959; D. R. Read, 1996; H. L. Roediger & K. B. McDermott, 1995) were evaluated in 7- to 12-year-old children (N = 151). Instead of a traditional analysis of variance, the authors used a relatively novel statistical analysis technique, latent class factor analysis, to test the hypotheses pertaining to the effect of semantic relatedness and study opportunity on childrens true and false recognition given their low or high verbatim-trace and gist-trace level. The results showed that variation in true recognition of target words from semantically related and unrelated word lists that were either studied once or repeated could be explained well by variation in verbatim-trace and gist-trace level. Variation in false recognition of semantically related distractors also could be explained by variation in gist-trace level, but the recollection-rejection hypothesis was not confirmed. The variable age was positively but weakly related to gist-trace level, but no significant relationship was found between age and verbatim-trace level.