The authors performed a meta-analysis of the distributed practice effect to illuminate the effects of temporal variables that have been neglected in previous reviews. This review found 839 assessments of distributed practice in 317 experiments located in 184 articles. Effects of spacing (consecutive massed presentations vs. spaced learning episodes) and lag (less spaced vs. more spaced learning episodes) were examined, as were expanding interstudy interval (ISI) effects. Analyses suggest that ISI and retention interval operate jointly to affect final-test retention; specifically, the ISI producing maximal retention increased as retention interval increased. Areas needing future research and theoretical implications are discussed.

The term "learning styles" refers to the concept that individuals differ in regard to what mode of instruction or study is most effective for them. Proponents of learning-style assessment contend that optimal instruction requires diagnosing individuals' learning style and tailoring instruction accordingly. Assessments of learning style typically ask people to evaluate what sort of information presentation they prefer (e.g., words versus pictures versus speech) and/or what kind of mental activity they find most engaging or congenial (e.g., analysis versus listening), although assessment instruments are extremely diverse. The most common-but not the only-hypothesis about the instructional relevance of learning styles is the meshing hypothesis, according to which instruction is best provided in a format that matches the preferences of the learner (e.g., for a "visual learner," emphasizing visual presentation of information). The learning-styles view has acquired great influence within the education field, and is frequently encountered at levels ranging from kindergarten to graduate school. There is a thriving industry devoted to publishing learning-styles tests and guidebooks for teachers, and many organizations offer professional development workshops for teachers and educators built around the concept of learning styles. The authors of the present review were charged with determining whether these practices are supported by scientific evidence. We concluded that any credible validation of learning-styles-based instruction requires robust documentation of a very particular type of experimental finding with several necessary criteria. First, students must be divided into groups on the basis of their learning styles, and then students from each group must be randomly assigned to receive one of multiple instructional methods. Next, students must then sit for a final test that is the same for all students. Finally, in order to demonstrate that optimal learning requires that students receive instruction tailored to their putative learning style, the experiment must reveal a specific type of interaction between learning style and instructional method: Students with one learning style achieve the best educational outcome when given an instructional method that differs from the instructional method producing the best outcome for students with a different learning style. In other words, the instructional method that proves most effective for students with one learning style is not the most effective method for students with a different learning style. Our review of the literature disclosed ample evidence that children and adults will, if asked, express preferences about how they prefer information to be presented to them. There is also plentiful evidence arguing that people differ in the degree to which they have some fairly specific aptitudes for different kinds of thinking and for processing different types of information. However, we found virtually no evidence for the interaction pattern mentioned above, which was judge...

Some researchers have suggested that although feedback may enhance performance during associative learning, it does so at the expense of later retention. To examine this issue, subjects (N = 258) learned Luganda-English word pairs. After 2 initial exposures to the materials, subjects were tested on each item several times, with the presence and type of feedback varying between subjects. A final test followed after 1 week. Supplying the correct answer after an incorrect response not only improved performance during the initial learning session--it also increased final retention by 494%. On the other hand, feedback after correct responses made little difference either immediately or at a delay, regardless of whether the subject was confident in the response. Practical and theoretical implications are discussed.

Every day students and instructors are faced with the decision of when to study information. The timing of study, and how it affects memory retention, has been explored for many years in research on human learning. This research has shown that performance on final tests of learning is improved if multiple study sessions are separated-i.e., "spaced" apart-in time rather than massed in immediate succession. In this article, we review research findings of the types of learning that benefit from spaced study, demonstrations of these benefits in educational settings, and recent research on the time intervals during which spaced study should occur in order to maximize memory retention. We conclude with a list of recommendations on how spacing might be incorporated into everyday instruction.

In most mathematics textbooks, each set of practice problems is comprised almost entirely of problems corresponding to the immediately previous lesson. By contrast, in a small number of textbooks, the practice problems are systematically shuffled so that each practice set includes a variety of problems drawn from many previous lessons. The standard and shuffled formats differ in two critical ways, and each was the focus of an experiment reported here. In Experiment 1, college students learned to solve one kind of problem, and subsequent practice problems were either massed in a single session (as in the standard format) or spaced across multiple sessions (as in the shuffled format). When tested 1 week later, performance was much greater after spaced practice. In Experiment 2, students first learned to solve multiple types of problems, and practice problems were either blocked by type (as in the standard format) or randomly mixed (as in the shuffled format). When tested 1 week later, performance was vastly superior after mixed practice. Thus, the results of both experiments favored the shuffled format over the standard format.

Relatively few experiments have measured the time course of free recall from episodic or semantic memory. Of those that have, most report that cumulative recall is a negatively accelerated exponential (or hyperbolic) function that is characterized by two properties: asymptotic recall and rate of approach to asymptote. The most common measure of free recall performance (viz., the number of items recalled) provides a reasonably good estimate of asymptotic recall if a relatively long recall period is used (which is rare), but the effect of experimental manipulations on the rate of approach to asymptote cannot be determined without timing when recall responses occur. The research reviewed herein suggests that the rate of approach to asymptote may offer an estimate of the breadth of search through long-term memory. The search in question, unlike most ofthose investigated in the memory literature, is unique in that it requires minutes rather than milliseconds to complete.When subjects attempt to generate items from a semantic category or to recall a recently presented list of words, they do not complete the task in an instant. Instead, their performance is almost invariably characterized by intermittent successes occurring over an extended period of time. In spite of this interesting fact, memory researchers have exhibited an overwhelming preference for recording which (or how many) items are recalled during some brief period of time, regardless of the speed with which those items have been retrieved. Does the time course of free recall offer any useful information about the nature of retrieval? Because this subject is an old one that commands little attention today, one might assume that the answer is no. However, a review of the extant literature, limited as it is, suggests otherwise.Exactly what can be learned that is not already known by studying the dynamics of free recall? First, the studies that have tracked the time course of recall usually reveal that subjects continue to make progress far beyond the 1-or 2-min recall period typically provided. Indeed, Roediger and Thorpe (1978)-to take one example that will be considered in detail later-reported that recall on an episodic memory task continued to increase more than 20 min into the recall period. Moreover, a clear difference in the level of recall between two conditions (easily named pictures vs. words) became evident only after several minutes had elapsed. Had these authors used the standard brief recall period, they might have mistakenly concluded that the two conditions produced equal levels of performance. How often are incorrect conclusions arrived at because the recall period is too brief? The answer is Correspondence concerning this article should be sent to John Wixted, Department of Psychology-OfOs, University of California, San Diego, La Jolla, CA 92093. 89 unknown because most researchers simply ignore the potential problem.Second, most of the literature reviewed below suggests that the time course of free recall, like reaction time in the Sternber...

To achieve enduring retention, people must usually study information on multiple occasions. How does the timing of study events affect retention? Prior research has examined this issue only in a spotty fashion, usually with very short time intervals. In a study aimed at characterizing spacing effects over significant durations, more than 1,350 individuals were taught a set of facts and--after a gap of up to 3.5 months--given a review. A final test was administered at a further delay of up to 1 year. At any given test delay, an increase in the interstudy gap at first increased, and then gradually reduced, final test performance. The optimal gap increased as test delay increased. However, when measured as a proportion of test delay, the optimal gap declined from about 20 to 40% of a 1-week test delay to about 5 to 10% of a 1-year test delay. The interaction of gap and test delay implies that many educational practices are highly inefficient.

Previous research shows that interleaving rather than blocking practice of different skills (e.g. abcbcacab instead of aaabbbccc) usually improves subsequent test performance. Yet interleaving, but not blocking, ensures that practice of any particular skill is distributed, or spaced, because any two opportunities to practice the same task are not consecutive. Hence, because spaced practice typically improves test performance, the previously observed test benefits of interleaving may be due to spacing rather than interleaving per se. In the experiment reported herein, children practiced four kinds of mathematics problems in an order that was interleaved or blocked, and the degree of spacing was fixed. The interleaving of practice impaired practice session performance yet doubled scores on a test given one day later. An analysis of the errors suggested that interleaving boosted test scores by improving participants' ability to pair each problem with the appropriate procedure.When practice is interleaved rather than blocked, the practice of different skills is intermixed rather than grouped by type (e.g. abcbcacab instead of aaabbbccc). In most introductory statistics textbooks, for example, the practice problems requiring a particular statistical test (e.g. independent samples t test) are blocked together in a set that typically follows the lesson on that statistical test. With interleaved practice, by contrast, each lesson is followed by a set of practice problems drawn from many previous lessons so that no two problems of the same kind appear consecutively, thereby requiring students to choose the appropriate statistical test on the basis of the problem itself. Several studies have shown that interleaving yields better subsequent test performance than does blocking. In these studies, however, practice in the interleaving condition was distributed or spaced, and, as detailed below, this confound worked in favour of the observed benefits of interleaving. The present study assessed the effects of interleaving while equating the degree of spacing.