Hypermnesia and total retrieval time

Recall performance sometimes improves over repeated recall attempts, a phenomenon dubbed hypermnesia. A critical theoretical issue is whether hypermnesia is due to repeated testing per se or increased retrieval time. The present experiments investigated by contrasting five testing conditions. All participants were presented with the same study list followed by either two shorter recall tests or a single longer test. In the multiple test conditions, the tests were either separated by a (filled) 7-minute interval (the multiple-split condition), or presented consecutively, with no break (the multiple-immediate condition). In the single test conditions, the test either began at the start of the recall session, after a (filled) 7-minute delay, or with a 7-minute interruption inserted in the middle. The multiple-split condition produced more reminiscence and hypermnesia than the multiple-immediate condition. More importantly, the multiple-split condition produced greater cumulative recall than any of the other conditions (which did not differ among themselves). That is, single and repeated recall tests of equal total duration are not functionally equivalent.     

Hypermnesia: The role of multiple retrieval cues

We demonstrate that encoding multiple cues enhances hypermnesia. College students were presented with 36 (Experiment 1) or 60 (Experiments 2 and 3) sets of words and were asked to encode the sets under single- or multiple-cue conditions. In the single-cue conditions, each set consisted of a cue and a target. In the multiple-cue conditions, each set consisted of three cues and a target. Following the presentation of the word sets, the participants received either three cued recall tests (Experiments 1 and 2) or three free recall tests (Experiment 3). With this manipulation, we observed greater hypermnesia in the multiple-cue conditions than in the single-cue conditions. Furthermore, the greater hypermnesic recall resulted from increased reminiscence rather than reduced intertest forgetting. The present findings support the hypothesis that the availability of multiple retrieval cues plays an important role in hypermnesia.     

Vividness of image and retrieval time

The relationship between vividness of image and information-retrieval time was examined. In an integrated-image condition the retrieval time for a vivid-image set was shorter than the retrieval time for a dim-image set; on the other hand, there was no difference in retrieval time between vivid- and dim-image sets in a verbal-rehearsal condition. Since the retrieval time difference between the two sets in the integrated-image group was not an artifact of image-construction time or presentation position, it was concluded that vividness of image affected information-retrieval time in the integrated-image group. The results were explained in terms of a picture-metaphor hypothesis of imagery.     

Hypermnesia and the Role of Delay between Study and Test

Hypermnesia is increased recall across repeated tests in the absence of any further study opportunities. Although over the years many factors have been identified that influence hypermnesia, to date not much is known about the role of delay between study and test for the effect. This study addressed the issue in four experiments. Employing both words and pictures as study material, we compared hypermnesia after shorter delay (3 min or 11.5 min) and longer delay (24 h or 1 week) between study and test. Recall occurred over three successive tests, using both free recall (Experiments 1, 2, and 4) and forced recall testing (Experiment 3). In forced recall tests, subjects are instructed to recall as many items as possible, but if unable to remember all studied items, to fill in the remaining spaces with their best guesses. With free recall testing, hypermnesia increased with delay and the effect was driven mainly by reduced item losses between tests. These results suggest a link between hypermnesia and the testing effect, which shows that demanding retrieval practice, as it happens after longer delay, can improve recall by reducing the forgetting of the practiced items. In contrast, with forced recall testing, hypermnesia decreased with delay and was even absent after longer delay. The findings indicate that recall format can influence hypermnesia and different mechanisms may mediate the effects of repeated testing in the two recall conditions.     

Hypermnesia using auditory input.

The author investigated whether hypermnesia would occur with auditory input. In addition, the author examined the effects of subjects' knowledge that they would later be asked to recall the stimuli. Two groups of 26 subjects each were given three successive recall trials after they listened to an audiotape of 59 high-imagery nouns. The subjects in the uninformed group were not told that they would later be asked to remember the words; those in the informed group were. Hypermnesia was evident, but only in the uninformed group.     

Hypermnesia in free recall and cued recall

In three experiments, categorized lists and both free recall and cued recall tests were used to examine hypermnesia. In Experiment 1, materials were drawn from obvious and nonobvious categories in an attempt to vary the amount of relational processing at encoding. The study materials in Experiment 2 consisted of a long word list that comprised several exemplars from each of a number of common categories. In Experiment 3, a single exemplar was drawn from each of 45 categories. In each experiment, similar magnitudes of hypermnesia were obtained on free and cued recall tests. Examination of the specific items recalled across tests indicated that similar processes underlie the hypermnesic effect for both test conditions. Implications of the results for extant accounts of the hypermnesic effect are discussed. It is concluded that the dynamics of retrieval processes change in a systematic fashion across repeated tests and the retention interval following study and that an adequate account of the nature of these changes in retrieval dynamics is essential to our understanding of hypermnesia and related phenomena.     

The relation of tip-of-the-tongue states and retrieval time

The tip-of-the-tongue state (TOT) is the phenomenological experience that a word is on the verge of being recalled. Participants rated TOTs as either emotional or nonemotional. In Experiment 1, given general-information questions, participants spent more time attempting retrieval during emotional TOTs than during nonemotional TOTs or n-TOTs (retrieval failures not accompanied by TOTs). Experiment 2 replicated the effect that TOTs show longer retrieval times than n-TOTs. In Experiment 3, with word definitions as stimuli, retrieval times were longer for emotional TOTs. Experiment 4 showed the same relation between retrieval times and TOTs even when participants made retrospective decisions about whether they had experienced a TOT before they retrieved the correct target. Valence of emotion was correlated with correct resolution of the TOT. These results are discussed in the context of a metacognitive model, in which TOTs serve to monitor and control cognition.     

Hypermnesia: Age-related differences between young and older adults

Hypermnesia is a net improvement in memory performance that occurs across tests in a multitest paradigm with only one study session. Our goal was to identify possible age-related differences in hypermnesic recall. We observed hypermnesia for young adults using verbal (Experiment 1) as well as pictorial (Experiment 2) material, but no hypermnesia for older adults in either experiment. We found no age-related difference in reminiscence (Experiments 1 and 2), though there was a substantial difference in intertest forgetting (Experiments 1 and 2). Older, relative to young, adults produced more forgetting, most of which occurred between Tests 1 and 2 (Experiments 1 and 2). Furthermore, older, relative to young, adults produced more intrusions. We failed to identify a relationship between intrusions and intertest forgetting. We suggest that the age-related difference in intertest forgetting may be due to less efficient reinstatement of cues at test by older adults. The present findings reveal that intertest forgetting plays a critical role in hypermnesic recall, particularly for older adults.     

Hypermnesia: the role of repeated testing

The present study was designed to determine whether the increased recall of pictures across repeated tests (hypermnesia) is due to increasing strength of imaginal traces during the retention interval or to increased retrieval practice from prior tests. Subjects studied 60 pictures and then recalled them after various delays that were filled with instructions and, in two cases, reading a passage. Recall on a first test showed no change with retention interval. With retention interval held constant, however, the number of pictures recalled varied directly with the number of prior tests subjects had been given. This finding points up the critical nature of retrieval factors in producing hypermnesia.     

Proper Name Hypermnesia in an Autistic Subject

The case study of an autistic “savant” subject with person names hypermnesia is presented. NM's performance in memorizing person names is compared to that of normal controls, IQ-matched controls, and one overtrained control. The data show a selective hypermnesia for both the free recall of person names and the recognition of faces. Recall of common names and of biographical informations linked to faces is unremarkable. NM's hypermnesia is restricted to list learning as low performance is observed in face-name learning tasks. A comparison of the data with that of the overtrained control indicates that training is not responsible for NM's pattern of results. These findings, when combined with previous results involving proper names, demonstrate a double dissociation between proper names and other types of semantic and referential information. However, aspects of NM's performance pattern are more compatible with a network model of proper names than with a sequential model. We propose that the contextual regularity of proper names in ecological situations can be responsible for their high memorization by NM.     

The time course of object-feature retrieval in recognition

The time course of perception and retrieval of object features was investigated. Participants completed a perceptual matching task and 2 recognition tasks under time pressure. The recognition tasks imposed different retention loads. A stochastic model of feature sampling with a Bayesian decision component was used to estimate the rate of feature perception and the rate of retrieval of feature information. The results demonstrated that retrieval rates did not differ among object features if only a single object was held in memory. If 2 objects were retained in memory, differences among retrieval rates of features emerged, indicating that features that were quickly perceived were also quickly retrieved. The results from the 2-object retention condition are compatible with process reinstatement models of retrieval.     

Hypermnesia occurs in recall but not in recognition

Two experiments investigated the effect of encoding conditions and type of test (recall vs. recognition) on the phenomenon of hypermnesia (improved performance across repeated tests). Subjects in Experiment 1 studied a list of words using either imaginal or semantic elaboration strategies and then received three successive tests. Different groups of subjects received either free recall, four-alternative forced-choice recognition, or yes/no recognition tests. Reliable hypermnesia was found only in the recall conditions, with the recognition conditions showing either no change in performance levels across tests (forced-choice tests) or significant forgetting (yes/no tests). In Experiment 2, subjects studied a list of words, and encoding was manipulated using three orienting tasks. Once again, hypermnesia was found with the recall tests but not with the forced choice recognition tests. Finding hypermnesia in recall but not in recognition indicates that retrieval processes in recall play a major role in producing hypermnesia. Also, the finding that the magnitude of the recall hypermnesias increased with an increase in total cumulative recall levels across study conditions suggests that cumulative recall levels are an important factor in determining the presence or absence of recall hypermnesia.     

The time course of perception and retrieval in matching and recognition

A four-part experiment was carried out to study the relationship between the time course of object-feature perception and the time course of retrieval of object information from memory. The experiment consisted of 2 perceptual matching tasks, and 2 perceptual recognition tasks. In all 4 tasks, participants provided speeded judgments of the identity of 2 objects. A stochastic feature-sampling model was used to estimate the time needed for feature perception and the time needed for retrieval of feature information. No evidence was found for a systematic relationship between perception times and retrieval times for individual features. Indeed, the model applications indicated that retrieval times were constant for different features, whereas perception rates varied across the features.     

Hypermnesia: A further examination of age differences between young and older adults

Previous studies that examined age differences in hypermnesia reported inconsistent results. The present experiment investigated whether the different study materials in these studies were responsible for the inconsistency. In particular, the present experiment examined whether the use of a video, as opposed to words and pictures, would eliminate previously reported age differences in hypermnesia. Fifteen college students and 15 older adults viewed a 3‐minute video clip followed by two free‐recall tests. The results indicated that older adults, as a whole, did not show hypermnesia. However, when older adults were divided into low and high memory groups based on test 1 performance, the high memory group showed hypermnesia whereas the low memory group did not show hypermnesia. The older adults in the low memory group were significantly older than the older adults in the high memory group – indicating that hypermnesia is inversely related to age in older adults. Reminiscence did not show an age‐related difference in either the low or high memory group whereas inter‐test forgetting did show an age difference in the low memory group. As expected, older adults showed greater inter‐test forgetting than young adults in the low memory group. Findings from the present experiment suggest that video produces a pattern of results that is similar to the patterns obtained when words and pictures are used as study material. Thus, it appears that the nature of study material is not the source of inconsistency across the previous studies.     

Hypermnesia for high-imagery words: The effects of interpolated tasks

The purpose of this study was to determine whether hypermnesia (improved net recall over time) can be differentially affected by manipulating the nature of tasks performed during the intervals between successive recall trials. In Experiment 1, all subjects were asked to imaginally encode separate words and were tested three times for recall. The control group (no interpolated task) produced the hypermnesia effect. Both groups performing interpolated tasks showed significantly lower recall. A second experiment was conducted in order to replicate these results and to examine the effects of intertest rehearsal on hypermnesia. In Experiment 2, subjects were asked to encode pairs of words using interactive-imagery instructions. Six different interpolated task conditions were employed, varying in the degree to which subsystems of working memory were used. Groups performing imaginal interpolated tasks showed no hypermnesia, whereas those performing nonimaginal tasks did. These findings suggest that access to working memory (see Baddeley, 1986) is not necessary for hypermnesia.     

Forward and backward recall: different response time patterns,same retrieval order

How do people retrieve information in forward and backward recall? To address this issue, we examined response times in directional recall as a function of serial position and list length. Participants memorized lists of four to six words and entered responses at the keyboard. Recall direction was postcued. Response times exhibited asymmetry in terms of direction. In forward recall, response times peaked at the first position, leveling off for subsequent positions. Response times were slower in backward recall than in forward recall and exhibited an inverse U-shaped function with an initial slowdown followed by a continuous speedup. These asymmetries have implications for theoretical models of retrieval in serial recall, including temporal-code, rule-based, and network models. The response time pattern suggests that forward recall proceeds in equal steps across positions, whereas backward recall involves repeated covert cycles of forward recall. Thus, retrieval in both directions involves a forward search.