Christopher N. Wahlheim

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.

Test-enhanced learning of natural concepts: effects on recognition memory, classification, and metacognition.

Three experiments examined testing effects on learning of natural concepts and metacognitive assessments of such learning. Results revealed that testing enhanced recognition memory and classification accuracy for studied and novel exemplars of bird families on immediate and delayed tests. These effects depended on the balance of study and test trials during training. Metacognitive measures provided results suggesting that participants were aware of the beneficial effects of testing. A new measure of metacognition at the level of categories is introduced and shown to be potentially useful for theory and applied purposes. It is argued that focusing on optimizing the learning of natural concepts encourages the convergence of theorizing about memory, concept learning, and metacognition and holds promise for the development of applications to education.

Remembering change: The critical role of recursive remindings in proactive effects of memory

In three experiments, we examined the role of the detection and recollection of change in proactive effects of memory in a classic A–B, A–D paradigm. Participants studied two lists of word pairs that included pairs repeated across lists (A–B, A–B), pairs with the same cue but a changed response (A–B, A–D) in the second list, and control pairs (A–B, C–D). The results revealed that performance on A–B, A–D pairs reflected a mixture of facilitation and interference effects. Proactive facilitation occurred when changes in responses were detected and recollected, whereas proactive interference occurred when change was not detected or when it was not recollected. We describe detecting change as involving recursive remindings that result in memory for the List 1 response being embedded in the representation of memory for the List 2 response. These embedded representations preserve the temporal order of the responses. Our findings highlight the importance of detection and recollection of change for proactive effects of memory.

Learning to diminish the effects of proactive interference: reducing false memory for young and older adults.

Results from two experiments revealed that prior experience with proactive interference (PI) diminished PI’s effects for both young and older adults. Participants were given two rounds of experience, with different materials, in a situation that produced PI. Comparisons with a control condition showed that the effects of PI on accuracy and on high-confidence intrusion errors (false memory) were reduced on the second round, as compared with those on the first. Also, the ability of confidence to diagnose accuracy of responding improved across rounds. Effects of prior experience with PI depended on feedback given at the time of test (Experiment 1). At least in part, the diminishment of PI resulted from participants’ allocating more attention to interference items during study in the second round than in the first (Experiment 2). Implications of the results for interpreting age differences in PI and false memory are discussed.

On the importance of looking back: the role of recursive remindings in recency judgments and cued recall.

Suppose that you were asked which of two movies you had most recently seen. The results of the experiments reported here suggest that your answer would be more accurate if, when viewing the later movie, you were reminded of the earlier one. In the present experiments, we investigated the role of remindings in recency judgments and cued-recall performance. We did this by presenting a list composed of two instances from each of several different categories and later asking participants to select (Exp. 1) or to recall (Exp. 2) the more recently presented instance. Reminding was manipulated by varying instructions to look back over memory of earlier instances during the presentation of later instances. As compared to a control condition, cued-recall performance revealed facilitation effects when remindings occurred and were later recollected, but interference effects in their absence. The effects of reminding on recency judgments paralleled those on cued recall of more recently presented instances. We interpret these results as showing that reminding produces a recursive representation that embeds memory for an earlier-presented category instance into that of a later-presented one and, thereby, preserves their temporal order. Large individual differences in the probabilities of remindings and of their later recollection were observed. The widespread importance of recursive reminding for theory and for applied purposes is discussed.

The role of reminding in the effects of spaced repetitions on cued recall: Sufficient but not necessary.

Three experiments examined the role of study-phase retrieval (reminding) in the effects of spaced repetitions on cued recall. Remindings were brought under task control to evaluate their effects. Participants studied 2 lists of word pairs containing 3 item types: single items that appeared once in List 2, within-list repetitions that appeared twice in List 2, and between-list repetitions that appeared once in List 1 and once in List 2. Our primary interest was in performance on between-list repetitions. Detection of between-list repetitions was encouraged in an n-back condition by instructing participants to indicate when a presented item was a repetition of any preceding item, including items presented in List 1. In contrast, detection of between-list repetitions was discouraged in a within-list back condition by instructing participants only to indicate repetitions occurring in List 2. Cued recall of between-list repetitions was enhanced when instructions encouraged detection of List 1 presentations. These results accord with those from prior experiments showing a role of study-phase retrieval in effects of spacing repetitions. Past experiments have relied on conditionalized data to draw conclusions, producing the possibility that performance benefits merely reflected effects of item selection. By bringing effects under task control, we avoided that problem. Our results provide evidence that reminding resulting from retrieval of earlier presentations plays a role in the effects of spaced repetitions on cued recall. However, our results also reveal that such retrievals are not necessary to produce an effect of spacing repetitions.

Self-regulated learning of a natural category: Do people interleave or block exemplars during study?

Despite decades of research focused on the representation of concepts, little is known about the influence of self-regulatory processes when learning natural categories. Such work is vital, as many contexts require self-regulation when we form complex concepts. Previous research has demonstrated that interleaving, as compared to blocking, can improve classification. Thus, as an initial step to explore self-regulated learning of natural concepts, we evaluated whether people chose to block or interleave their practice. According to the search-for-differences hypothesis, people attempt to identify features of birds that distinguish one category (i.e., bird family) from another, and hence should interleave their study. According to the search-for-similarities hypothesis, people attempt to identify features that indicate inclusion into a single category, and hence are expected to block their study. To evaluate these hypotheses, we had participants learn exemplar birds (e.g., Song Sparrow) with their respective bird families (e.g., Sparrow) by selecting the order in which to study bird families. Across four experiments, different formats for selecting exemplars for study were used, so as to provide converging evidence for how participants regulated their learning. Participants overwhelmingly preferred to block their study, even though interleaving is normatively better for learning.

Metacognitive judgments of repetition and variability effects in natural concept learning: evidence for variability neglect.

In four experiments, we examined the effects of repetitions and variability on the learning of bird families and metacognitive awareness of such effects. Of particular interest was the accuracy of, and bases for, predictions regarding classification of novel bird species, referred to as category learning judgments (CLJs). Participants studied birds in high repetitions and high variability conditions. These conditions differed in the number of presentations of each bird (repetitions) and the number of unique species from each family (variability). After study, participants made CLJs for each family and were then tested. Results from a classification test revealed repetition benefits for studied species and variability benefits for novel species. In contrast with performance, CLJs did not reflect the benefits of variability. Results showed that CLJs were susceptible to accessibility-based metacognitive illusions produced by additional repetitions of studied items.

Memory for flip-flopping: Detection and recollection of political contradictions

During political campaigns, candidates often change their positions on controversial issues. Does changing positions create confusion and impair memory for a politician’s current position? In 3 experiments, two political candidates held positions on controversial issues in two debates. Across the debates, their positions were repeated, changed, or held only in the second debate (control). Relative to the control condition, recall of the most recent position on issues was enhanced when change was detected and recollected, whereas recall was impaired when change was not recollected. Furthermore, examining the errors revealed that subjects were more likely to intrude a Debate 1 response than to recall a blend of the two positions, and that recollecting change decreased Debate 1 intrusions. We argue that detecting change produces a recursive representation that embeds the original position in memory along with the more recent position. Recollecting change then enhances memory for the politician’s positions and their order of occurrence by accessing the recursive trace.

The role of detection and recollection of change in list discrimination

In two experiments, we examined the importance of the detection and recollection of change for list discrimination. Two lists of pairs were presented, with the right-hand member being changed between lists for some pairs. Participants in Experiment 1 were instructed to explicitly indicate when they detected a change between pairs during the presentation of List 2, whereas participants in Experiment 2 were not instructed to do so. At the time of test, participants in both experiments were presented with a pair and asked whether it had been presented in List 2. Next, recollection of change was measured by asking whether the right-hand member of the pair was changed between the lists. The results from Experiment 1 revealed high correspondence between the detection of change during the presentation of List 2 and the recollection of change at the time of test. Consequently, change recollection at test can serve as a measure of earlier change detection, in combination with access to memory for change at the time of test. In both experiments, as compared to control conditions, proactive facilitation in list discrimination was observed when change was recollected, whereas proactive interference was observed when change was not recollected. These results were interpreted as showing that recursive reminding—bringing a List 1 pair to mind during the presentation of its changed List 2 pair—embeds memory for the earlier event into memory for the later event, and doing so preserves information about list membership.