Mixing strong and weak targets provides no evidence against the unequal-variance explanation of ʐROC slope: a comment on Koen and Yonelinas (2010)

Koen and Yonelinas (2010; K&Y) reported that mixing classes of targets that had short (weak) or long (strong) study times had no impact on ?ROC slope, contradicting the predictions of the encoding variability hypothesis. We show that they actually derived their predictions from a mixture unequal-variance signal detection (UVSD) model, which assumes 2 discrete levels of strength instead of the continuous variation in learning effectiveness proposed by the encoding variability hypothesis. We demonstrated that the mixture UVSD model predicts an effect of strength mixing only when there is a large performance difference between strong and weak targets, and the strength effect observed by K&Y was too small to produce a mixing effect. Moreover, we re-analyzed their experiment along with another experiment that manipulated the strength of target items. The mixture UVSD model closely predicted the empirical mixed slopes from both experiments. The apparent misfits reported by K&Y arose because they calculated the observed slopes using the actual range of ?-transformed false-alarm rates in the data, but they computed the predicted slopes using an extended range from - 5 to 5. Because the mixed predictions follow a slightly curved ?ROC function, different ranges of scores have different linear slopes. We used the actual range in the data to compute both the observed and predicted slopes, and this eliminated the apparent deviation between them.     

Episodic feeling-of-knowing resolution derives from the quality of original encoding

In recent studies, researchers have argued for adult age-related deficits in the resolution of episodic feeling of knowing (FOK) owing to a decline in inferential processes. In the present study, we introduce the memory constraint hypothesis, which argues that deficits are an outcome of differences in the level of learning. A repetition delay paradigm for a list of paired-associate items showed that repeated presentations at encoding increased memory performance and in turn increased FOK resolution for unrecalled items. Older adults who were given a 48-h delay between encoding and subsequent tests (and FOKs) had equivalent memory performance to younger adults who were given a 7-day delay. In this case, age equivalence arose in FOK resolution except at the lowest levels of recognition in the single-presentation condition. The use of effective strategies during encoding correlated with memory performance and FOKs, even for unrecalled pairs. These results are inconsistent with an inferential-deficit explanation of age deficits in FOK resolution; they point to the importance of original encoding quality as a potent contributor to FOK resolution, and they argue for equating age groups on memory performance when evaluating the episodic FOK resolution of age differences.     

Evaluating the unequal-variance and dual-process explanations of zROC slopes with response time data and the diffusion model

We tested two explanations for why the slope of the z-transformed receiver operating characteristic (zROC) is less than 1 in recognition memory: the unequal-variance account (target evidence is more variable than lure evidence) and the dual-process account (responding reflects both a continuous familiarity process and a threshold recollection process). These accounts are typically implemented in signal detection models that do not make predictions for response time (RT) data. We tested them using RT data and the diffusion model. Participants completed multiple study/test blocks of an "old"/"new" recognition task with the proportion of targets and the test varying from block to block (.21, .32, .50, .68, or .79 targets). The same participants completed sessions with both speed-emphasis and accuracy-emphasis instructions. zROC slopes were below one for both speed and accuracy sessions, and they were slightly lower for speed. The extremely fast pace of the speed sessions (mean RT=526) should have severely limited the role of the slower recollection process relative to the fast familiarity process. Thus, the slope results are not consistent with the idea that recollection is responsible for slopes below 1. The diffusion model was able to match the empirical zROC slopes and RT distributions when between-trial variability in memory evidence was greater for targets than for lures, but missed the zROC slopes when target and lure variability were constrained to be equal. Therefore, unequal variability in continuous evidence is supported by RT modeling in addition to signal detection modeling. Finally, we found that a two-choice version of the RTCON model could not accommodate the RT distributions as successfully as the diffusion model.     

Comparing decay rates for accurate and false memories in the DRM paradigm

Although previous studies have consistently reported different forgetting rates for true and false memory when tested with recall, studies comparing the rates of decay for true and false recognition have reported inconsistent results. The present study attempted to clarify this inconsistency by comparing forgetting rates for true and false recognition in addition to addressing methodological differences among the previous studies. Recognition of list items and critical lures was assessed at six delays (2, 5, 10, 15, and 20 min, and 2 days). A comparison of power function slopes across item type provided evidence of slope differences such that false recognition decayed more quickly than true recognition, which is inconsistent with predictions from activation/ source-monitoring and fuzzy tracetheories.     

Item and order information in subject-performed tasks and experimenter-performed tasks

This study investigated the enactment effect from the perspective of the item-order hypothesis (e.g., M. Serra & J. S. Nairne, 1993). The authors assumed that in subject-performed tasks (SPTs), item encoding is improved but order encoding is disrupted compared with experimenter-performed tasks (EPTs), that order encoding of EPTs is only better in pure lists, and that the item--order hypothesis is confined to short lists. Item information was tested in recognition memory tests, order information in order reconstruction tasks, and both item and order information in free-recall tests. The results of 5 experiments using short (8 items) and long lists (24 items) in a design with list type (pure, mixed) and encoding condition (EPT, SPT) as factors supported the hypotheses.     

Repetition and laterality effects on recognition memory for words and pictures*

Recognition memory for a list of words was tested by presenting a series of items with Ss instructed to make positive responses to targets (list items) and negative responses to distractors (nonlist items). The test items were either words or pictures, and they were presented tachistoscopically either to the left or right visual field. The results showed mean response latencies to be generally faster for stimuli presented to the right visual field. Response times were faster for target and distractor stimuli on their second test presentations than on initial tests, but this effect was much larger for targets. Repetitions were shown to decrease the amount of time necessary to execute the stimulus encoding and initial retrieval stages of recognition. This was also true, although to a lesser extent, if different stimulus forms (words or pictures) were used on the two tests. Subsequent recognition stages, including memory search and decision processes. were apparently independent of test stimulus form.     

Order information and retrieval distinctiveness: recall of common versus bizarre material

The order-encoding hypothesis (E. L. DeLosh & M. A. McDaniel, 1996) assumes that serial-order information contributes to the retrieval of list items and that serial-order encoding is better for common items than bizarre items. In line with this account, Experiment 1 revealed better free recall and serial-order memory for common than for bizarre items in pure lists, and Experiment 2 showed that recall for bizarre items increased and the recall advantage of common items was eliminated when serial-order encoding for bizarre items was increased to the level of common items. However, inconsistent with a second assumption that bizarre-item advantages in mixed lists reflect better individual-item encoding for bizarre items, Experiments 3 and 4 showed that the bizarreness effect in mixed lists is eliminated when alternative retrieval strategies are encouraged. This set of findings is better explained by the differential-retrieval-process framework, which proposes that contextual factors (e.g., list composition) influence the extent to which various types of information are used at retrieval, with the bizarreness advantage in mixed lists dependent on a distinctiveness-based retrieval process.     

Effects of spacing repetitions on children's memory

Two experiments examined the effect of spacing repetitions within a word list on the free recall performance of elementary school children. In the first experiment, spacing repetitions facilitated recall, and the function relating recall of repeated items to the spacing between repetitions was the same throughout the age range investigated (first, third, and sixth graders). But, the function for these elementary school children reached asymptote at a much shorter spacing than the function typically reported for adults. The second experiment was designed to test an encoding variability explanation of spaced-repetition effects in elementary school children. Results for both third- and sixth-grade children were consistent with the hypothesis that differential encoding of repetitions facilitates performance and that spaced repetitions are remembered better because they are more likely to be differentially encoded. A theoretical framework was discussed that may be able to encompass both these results and another finding in the literature which indicates that differential encoding can sometimes impair rather than facilitate children's memory performance.     

Repetition effects in associative false recognition: Theme-based criterion shifts are the exception, not the rule

Previous reports have demonstrated that false memory for the critical items of associative lists decreases when lists are studied multiple times (Benjamin, 2001). In three experiments, we explored two hypotheses that might account for false memory reductions with repetition. Under an identification hypothesis, repetition decreases false memory because participants realise that critical items are absent from the list at encoding and thus reject them at test. Under a criterion shift hypothesis, repetition decreases false memory because it increases the discriminability of studied words from lures, causing participants to set a higher response criterion for positive recognition responses. Results uniquely supported the criterion shift hypothesis. Furthermore, results showed that participants only changed their criterion on separate recognition tests, not on an item-by-item basis within a single recognition test. The failure to establish separate criteria within a test increased false memory for repeated lists.     

List-method directed forgetting: Evidence for the reset-of-encoding hypothesis employing item-recognition testing

In list-method directed forgetting (LMDF), people are cued to forget a previously studied item list (List 1) and to learn a new list of items (List 2) instead. Such cuing typically enhances memory for the List 2 items, in both recall and (sometimes) item-recognition testing. It has recently been hypothesized that the enhancement effect for List 2 items (partly) reflects the result of a reset-of-encoding process. The proposal is that encoding efficacy decreases with an increase in study material, but the forget cue can reset the encoding process to make the encoding of early List 2 items as effective as the encoding of early List 1 items. An experiment is reported that examined the reset-of-encoding hypothesis with item-recognition testing, examining influences of items' serial learning position on the effects of the forget cue. Item-recognition tests were conducted separately for the two lists. Consistent with the reset-of-encoding hypothesis, the results showed strong enhancement effects for early List 2 items, but hardly any enhancement effects for middle and late List 2 items. Like in previous item-recognition studies, no cuing effects were found for List 1 items. The results support two-mechanism accounts of LMDF, which assume a critical role for a reset-of-encoding process for List 2 enhancement.     

The simultaneous learning effect: why does simultaneous task learning improve retention?

Despite the prevalence of encoding variables that have been shown to influence the rate of learning, very few affect the rate of forgetting of verbal material. However, when a list of words is learned simultaneously with other lists, the rate of forgetting is markedly lower than that of single-task learning. Although the magnitude of this simultaneous learning effect is large compared with typical list learning effects, it has received little empirical attention. Experiments 1 and 2 tested the hypothesis that the simultaneous learning effect is the result of a differential contribution of short-term memory during encoding. The results showed that the advantage for simultaneous task learning was obtained even under conditions that minimized the potential effects of short-term memory. Experiment 3 revealed that the simultaneous learning effect was larger when the specific items learned simultaneously were the same on each learning trial than when they were different. This finding supported a cuing explanation of the effect: the items from the other lists act as retrieval cues during delayed recall.     

Evaluating the role of distinctiveness in the generation effect

According to the distinctiveness interpretation, generating words from word fragments leads to more distinctive memory traces than reading intact words. As a test of this hypothesis, the generation effect was experimentally compared to three phenomena previously attributed to distinctiveness. Experiments 1 and 2 proved that the generation effect was unlike conceptual and encoding task distinctiveness. In Experiment 3 the generation effect and the effects of orthographic distinctiveness were compared. These two manipulations had similar effects on memory, but the effects were additive—challenging the hypothesis that the generation effect is a result of the unusual appearance of to-be-generated items. Thus, the generation effect is inconsistent with current theories of distinctiveness. The results were consistent with the hypothesis that generated items receive more encoding resources than read items, and that increased attention to generated items may be at the expense of attention to intact items in the list.     

Effects of age on measures of complex working memory span in the beagle dog (Canis familiaris) using two versions of a spatial list learning paradigm

The present study used two versions of a spatial list learning (SLL) paradigm to examine the effects of increased cognitive load on visuospatial working memory processes in young and old beagle dogs. In the first experiment, young, and a select group of old dogs were first presented with one item, then two, and then three, and were rewarded for responding to the novel position. The dogs were able to learn the task at short delays, but compared with young dogs, old dogs performed worse at delays of 10 sec, and could not reach longer delays. Analysis of errors indicated that memory was best for end items in the spatial list and that within sessions, the number of errors in later trials was greater than the number of errors in earlier trials. A second version of the task, a modified SLL (mSLL) was developed to control for the use of non-mnemonic strategies on the SLL task. In this version, the first two items were presented individually. Acquisition and maximal memory performance were better in the young relative to the old dogs. Similar to the original SLL design, memory for early list items was worse than memory for later list items in both young and old dogs. The within-session pattern of errors however, did not change from trial to trial on the mSLL. The present results suggest that multiple working memory processes are engaged during complex tests of visuospatial function and the neuroanatomical substrates controlling these processes are affected differentially by age in the beagle dog.     

No Benefit of Eye-Closure Rehearsal in a Unimodal Recognition Memory Test for Word Items

Recent studies have suggested that closing the eyes helps memory retrieval in recall tests for audiovisual clips that contain multimodal information. In two experiments, we examined whether eye-closure improves recognition memory performance for word lists presented unimodally (i.e., visually or aurally). In the encoding phase, participants saw or heard a list of unrelated, meaningful word items. After a fixed retention interval of 1 week (Experiment 1, n = 110) and 5 min (Experiment 2, n = 44), the participants were asked to mentally rehearse the items with their eyes open or closed, and then they performed a recognition test. The results revealed no effect of eye-closure rehearsal on recognition performance. We discuss the possible reasons why no eye-closure benefit was found in recognition memory tests for unrelated word items.     

The effect of forced recall on illusory recollection in younger and older adults

The effect of an initial forced recall test on later recall and recognition tests was examined in younger and older adults. Subjects were presented with categorized word lists and given an initial test under standard cued recall instructions (with a warning against guessing) or forced recall instructions (that required guessing); subjects were later given a cued recall test for the original list items. In 2 experiments, initial forced recall resulted in higher levels of illusory memories on subsequent tests (relative to initial cued recall), especially for older adults. Older adults were more likely to say they remembered rather than knew that forced guesses had occurred in the original study episode. The effect persisted despite a strong warning against making errors in Experiment 2. When a source monitoring test was given, older adults had more difficulty than younger adults in identifying the source of items they had originally produced as guesses. If conditions encourage subjects to guess on a first memory test, they are likely to recollect these guesses as actual memories on later tests. This effect is exaggerated in older adults, probably because of their greater source monitoring difficulties. Both dual process and source monitoring theories provide insight into these findings.     

Intention superiority effect on implicit memory of shopping lists: Activation and inhibition processes

Intentional memory is defined as the ability to remember to perform intentions in the future. Forming an intention such as “shopping” activates access to memories related to the products on the shopping list. As Intention Superiority Effect (ISE) studies show, these memories are more accessible in semantic and episodic memory, more activated over time and protected from competing representations. The inhibition of competing representations in intentional memory has been little examined so far. In this study we attempt to analyze changes in activation in the recall of products on a shopping list and competitors through implicit memory tasks. Sixty-five participants learned two shopping lists on a computer. Later, they were told to virtually buy one of them (prospective list) and not the other (neutral list). Prior to intentional task execution, they performed an implicit retrieval task in which we manipulated the appearance or not of cues from the intentional list and analyzed the influence of the items from the intentional list on items related to intentional and neutral lists. The main result of this study is that intention retrieval by intentional cues strengthens the activation of products related to the intentional list and/or inhibits competing products related to the neutral list. The inhibition is episodic rather than semantic in nature. The ISE requires the recall of the intention during the retention period through intentional cues for maintaining the intention. This seems to defend automatic recovery theories and not the intention persistence hypothesis. Also, the results are better explained by the directed forgetting paradigm rather than by the retrieval-induced forgetting paradigm.     

Young children's knowledge of their memory span: effects of task and experience

This study investigated the hypothesis that young children have knowledge about their memory that they may be unable to articulate, but are able to reflect on and use in problem-solving. Forty-eight kindergarteners made one of two types of judgments about their memory span for words. Half of the children made prospective verbal predictions about the number of words they thought they could recall from a list of 10. The other half made concurrent, nonverbal predictions by listening to words on a tape and manually stopping the tape when they heard as many words as they thought they could recall. Children's actual recall for words was then assessed. All children participated in multiple trials to assess the effect of task experience on their predictions. Analyses revealed that predictions made in the concurrent task were significantly more accurate than those made in the prospective task. All children lowered their predictions across trials, although only in the concurrent task were children's final-trial predictions not significantly greater than their actual recall. No meaningful effects or interactions were associated with actual recall scores. These results revealed that young children manifested greater memory knowledge when this knowledge was assessed through their concurrent problem-solving behavior rather than through their prospective verbal predictions.     

Response suppression contributes to recency in serial recall

Serial recall is often assumed to involve response suppression: the removal or inhibition of items already recalled so that they are not recalled again. Evidence for response suppression includes repetition inhibition and the separation of erroneous repetitions. Some theorists have suggested that response suppression, by eliminating competing responses, also contributes to recency in forward serial recall. We present experiments in which performance on the final item was examined as a function of whether or not the preceding retrievals entailed suppression of potential response competitors. In line with the predictions of response suppression, recency was found to be reduced when the earlier recall errors consisted of intrusion errors (which leave list items unsuppressed) rather than transposition errors (which involve suppression).     

Accuracy of feeling-of-knowing judgments for predicting perceptual identification and relearning

The feeding of knowing refers to predictions about subsequent memory performance on previously nonrecalled items. The most frequently investigated type of subsequent performance has been recognition. The present research explored predictive accuracy with two new feeling-of-knowing criterion tests (in addition to recognition): relearning and perceptual identification. In two experiments, people attempted to recall the answers to general-information questions such as, "What is the capital of Australia?", then made feeling-of-knowing predictions for all nonrecalled answers, and finally had a criterion test to assess the accuracy of the feeling-of-knowing predictions. Experiment 1 demonstrated that perceptual identification can be employed successfully as a criterion test for the feeling of knowing. This opens a new way for metamemory research via perception. Moreover, the feeling-of-knowing accuracy for predicting perceptual identification was not significantly correlated with the feeling-of-knowing accuracy for predicting recognition, in accord with the idea that these two tests assess memory differently. Experiment 2 demonstrated that relearning performance can also be predicted by feeling-of-knowing judgments. Both experiments showed that there is a positive relationship between the feeling of knowing and the amount of time elapsing before a memory search is terminated during recall. Further analyses showed that this relationship is substantial for nonrecalled items for which the person did not guess an answer (omission errors), but the relationship is null or negative for nonrecalled items that the person guessed incorrectly (commission errors). Several theoretical mechanisms that may underlie the feeling of knowing are proposed.     

Choosing words at the study phase: The self‐choice effect on memory from the viewpoint of connective processing1

Abstract: The self‐choice effect, that is the superior memory performance observed when participants are allowed to choose the item at the study phase than when they are not (lack of choice), has been explained by the encoding‐strategy hypothesis ( Takahashi, 1997 ). This hypothesis distinguishes between organizational processing, which focuses upon the relationship between chosen items, and item‐speci?c processing, which itself focuses on the elements that make the chosen item distinctive. The encoding‐strategy hypothesis predicts that the ability for the successive recall of chosen items can be affected by organized list (Experiment 1). The results of our experiments ran counter to the prediction and were interpreted by a new concept called connective processing, which would emphasize the relationship of paired items. Connective processing was examined through orienting tasks (Experiment 2). The results were more suitably interpreted by connective than organizational processing.