Trace resistance and the decay of long-term memory

A theory of storage in long-term memory is described which characterizes the trace by two properties: strength and resistance. The theory makes four assumptions: (a) The rate of decay of strength equals the force on the trace divided by the resistance. (b) Force is proportional to trace strength and to the similarity of current traces to the previously established trace. (c) Resistance increases as the square root of trace age. (d) The resistance of a trace transfers completely to subsequent increments. The theory accounts for long-term retention functions over delays from 1 min to 2 yr, long retrograde amnesia, unlearning, effects of multiple learning trials and spacing of practice, and possibly recency judgments and retention functions following relearning.     

Conceptual implicit memory: A developmental study

The widely accepted standpoint that implicit memory emerges earlier in development than explicit memory, and is more stable from childhood to adult age, is based on experimental data essentially collected in perceptual tasks. The present study was aimed at investigating whether these findings still hold when a more conceptual task is used. We compared the performance of children at two age levels (2nd and 4th grades) on a category-exemplar generation task. Results showed that performances of the two groups were comparable when the target items were typical of their categories, as in Experiment 2, and for a subset of the items in Experiment 1. However, the older children outperformed the younger children in Experiment 1 when the items selected were atypical of their categories. Interpretations of these findings are discussed.Preparation of this article was supported by the Centre National de la Recherche Scientifique (URA CNRS 316 and 1838), the Université de Bourgogne, and the Université René-Descartes     

A developmental study of latent absolute pitch memory

The ability to recall the absolute pitch level of familiar music (latent absolute pitch memory) is widespread in adults, in contrast to the rare ability to label single pitches without a reference tone (overt absolute pitch memory). The present research investigated the developmental profile of latent absolute pitch (AP) memory and explored individual differences related to this ability. In two experiments, 288 children from 4 to12 years of age performed significantly above chance at recognizing the absolute pitch level of familiar melodies. No age-related improvement or decline, nor effects of musical training, gender, or familiarity with the stimuli were found in regard to latent AP task performance. These findings suggest that latent AP memory is a stable ability that is developed from as early as age 4 and persists into adulthood.     

A developmental study of learning disabilities and memory

Seven-, ten-, and thirteen-year-old learning-disabled (LD) and non-learning-disabled (NORM) children were presented specially structured lists of 38 words each and tested for free recall. Each list contained only four semantically related words. Two of the four related words were presented contiguously (serial positions 9 and 10) and the other two words were spaced (serial positions 20 and 30). All children recalled disproportionately more adjacent words (item 9 or 10) than any other words. Spaced words (items 20 and 30) were less likely to be recalled by the younger children than by the older children and by the LDs than by the NORMS. These findings provided support for the distinction between automatic and purposive semantic processing. NORMs' recall was governed by purposive semantic processing to a greater extent than was LDs' recall. However, no group or age differences were observed in automatic semantic processing.     

A developmental study of semantic effects on recognition memory

Three experiments evaluated color specificity knowledge and related semantic effects on recognition memory. Experiment I provided the necessary baseline data to show that preschool and college students know the appropriate color of objects. Experiment II revealed semantic effects on recognition of children but not adults. In Experiment III a delay was introduced and adults showed semantic effects as well. The chroma of color-specific and non-color-specific items was remembered relatively well, although chroma recognition for these item types was somewhat different. The semantic effects on very young children's memory suggest deep level interpretive processing in children younger than those generally showing deliberate deployment of memory strategies.     

Working memory: A developmental study of phonological recoding

A cross-sectional study using children aged 3 to 7 years and a cross-sequential study using children aged between 5 and 8 years showed that the development of phonological recoding in working memory was more complex than the simple dichotomous picture portrayed in the current literature. It appears that initially children use no strategy in recall, which is proposed to represent the level of automatic activation of representations in long-term memory and the storage capacity of the central executive. This is followed by a period in which a visual strategy prevails, followed by a period of dual visual-verbal coding before the adult-like strategy of verbal coding finally emerges. The results are discussed in terms of three working memory models (Baddeley, 1990; Engle, 1996; Logie, 1996) where strategy use is seen as the development of attentional processes and phonological recoding as the development of inhibitory mechanisms in the central executive to suppress the habitual response set of visual coding.     

Memorabeatlia: A naturalistic study of long-term memory

Seventy-six undergraduates were given the titles and first lines of Beatles' songs and asked to recall the songs. Seven hundred and four different undergraduates were cued with one line from each of 25 Beatles' songs and asked to recall the title. The probability of recalling a line was best predicted by the number of times a line was repeated in the song and how early the line first appeared in the song. The probability of cuing to the title was best predicted by whether the line shared words with the title. Although the subjects recalled only 21% of the lines, there were very few errors in recall, and the errors rarely violated the rhythmic, poetic, or thematic constraints of the songs. Acting together, these constraints can account for the near verbatim recall observed. Fourteen subjects, who transcribed one song, made fewer and different errors than the subjects who had recalled the song, indicating that the errors in recall were not primarily the result of errors in encoding.     

Critical processes in serial short-term memory: A developmental study

Two experiments are described which were designed to test the possible involvement of two operations in developmental auditory serial short-term memory (SSTM), namely rehearsal proficiency and item identification. The experiments provided mainly negative support for the notion that these operations are critical in developmental SSTM. As an alternative, the possibility that developmental differences in SSTM might have their origins in the processing of speech sound patterns was discussed.     

The long-term retention of time: A developmental study

Two experiments investigated the age-related changes in long-term retention of duration and their effects on time judgement. Children aged 3, 5, and 8 years old were given a temporal bisection task with or without a 15-min interfering task (Experiment 1), or a retention delay lasting for 0 min, 15 min, or 24 hr (Experiment 2) between the presentation of the standard durations and the comparison stimulus durations. An interfering task and the increase of the retention delay significantly decreased the time sensitivity in the 3- and the 5-year-olds, and to a greater extent in the younger children, but had no effect in the 8-year-olds. This decrease in time sensitivity with the interfering task or the retention delay might be due to an increase in the variability of the remembered duration.     

A developmental study of semantic elaboration and interpretation in recognition memory

Two experiments examined semantic elaboration and interpretation in recognition memory of 4-year-olds and college students. Subjects were presented pictures of color-specific and non-color-specific items, and then tested for their recognition of the chroma of the items. In Experiment 1, one-half of the presentation items were black and white and one-half colored, and testing always involved one black and white and one colored choice. In Experiment 2, all of the presentation items were colored, and testing always involved two colored choices. In both studies, the pattern of results of the two age groups was similar. Experiments 1 and 2 indicated that recognition judgments were based on representations that were elaborated with preexperimentally acquired semantic color information, and Experiment 2 also indicated that recognition judgments were based on representations that contained interpretive information about the appropriateness of the colors of the items. The results were considered to support and extend the view that when young children and adults share a common knowledge base, they are likely to engage in similar and extensive semantic processing.     

A developmental phonological short-term memory deficit: a case study

A developmental case of phonological short-term memory deficit was studied in a highly educated subject. The subject, BS, who had obtained a Ph.D. in molecular biology, demonstrated striking deficits on some short-term memory tasks, particularly for auditorily presented nonword lists. With visual presentation and with meaningful words, he often scored at a normal level. The results indicate a deficit in retaining phonological information but an ability to use visual, lexical, and semantic information to boost recall. Despite this phonological short-term memory deficit, BS scored at a normal level on a syntactic comprehension test and on reading of nonwords. He was impaired, however, on repeated list learning, learning of foreign vocabulary, and transcribing dictated materials. The implications of these results for models of short-term memory and the uses of phonological retention in cognitive processing are discussed.     

Memory span and short-term memory capacity: A developmental study

A memory span task involving series conditions comprised of several different types of material was administered to children from three grade levels (7–12 years of age). As expected, age differences were strongly affected by type of material, with two conditions (consonant letters, words) intended to restrict opportunities for chunking yielding age differences that were negligible, and one condition (consonant-vowel letters) constructed to maximize sequential probability yielding age differences that were large. This finding renders less plausible the popular notion that capacity increases with age, and suggests that age differences in memory span reflect chunking processes. Additional findings, which indicate that age differences in memory span are affected by method of presentation and stage of practice, suggest that these variables should be considered in studies aimed at estimating children's memory capacity.     

A developmental study of the effect of familiarity on short-term visual memory

An attempt was made to specify whether previously reported limitations on young children's full-report capacity lay in a smaller amount of available information, in a shorter trace duration of information in visual information storage (VIS), or in poorer coding of information into permanent storage. Five- and 8-year-olds and adults were shown an eight-item array of figures. followed at varying intervals by an indicator signaling the subject to report the figure to which the indicator had pointed. The effects of three levels of familiarity or “labelability” were examined. While no age differences were revealed in amount of information available nor in the trace duration of information in VIS, strong age differences emerged in coding of information into permanent storage. Data on latency to verbal labeling and familiarity suggested that verbal labeling could not account for the age trends. Rather, the differences seemed to lie in the use of organized visual coding and rehearsal strategies by adults and their relative lack of use by children.     

Musical and verbal memory in Alzheimer’s disease: A study of long-term and short-term memory

Musical memory was tested in Alzheimer patients and in healthy older adults using long-term and short-term memory tasks. Long-term memory (LTM) was tested with a recognition procedure using unfamiliar melodies. Short-term memory (STM) was evaluated with same/different judgment tasks on short series of notes. Musical memory was compared to verbal memory using a task that used pseudowords (LTM) or syllables (STM). Results indicated impaired musical memory in AD patients relative to healthy controls. The deficit was found for both long-term and short-term memory. Furthermore, it was of the same magnitude for both musical and verbal domains whether tested with short-term or long-term memory tasks. No correlation was found between musical and verbal LTM. However, there was a significant correlation between verbal and musical STM in AD participants and healthy older adults, which suggests that the two domains may share common mechanisms.     

Working memory: a developmental study of phonological recoding

A cross-sectional study using children aged 3 to 7 years and a cross-sequential study using children aged between 5 and 8 years showed that the development of phonological recoding in working memory was more complex than the simple dichotomous picture portrayed in the current literature. It appears that initially children use no strategy in recall, which is proposed to represent the level of automatic activation of representations in long-term memory and the storage capacity of the central executive. This is followed by a period in which a visual strategy prevails, followed by a period of dual visual-verbal coding before the adult-like strategy of verbal coding finally emerges. The results are discussed in terms of three working memory models (Baddeley, 1990; Engle, 1996; Logie, 1996) where strategy use is seen as the development of attentional processes and phonological recoding as the development of inhibitory mechanisms in the central executive to suppress the habitual response set of visual coding.     

A developmental psychopathology model of overgeneral autobiographical memory

Overgeneral memory (OGM) is a phenomenon that refers to difficulty retrieving specific autobiographical memories. The tendency to be overgeneral in autobiographical memory recall has been commonly observed among individuals with emotional disorders compared to those without emotional disorders. Despite significant advances in identifying mechanisms that underlie OGM, etiological models are not particularly developmental in nature and, instead, are focused on identifying isolated cognitive presentations of individuals with high OGM. The aim of the current paper is to utilize a developmental psychopathology framework, which emphasizes the interface between typical and atypical development, and risk and protective factors at multiple ecological levels, to propose a comprehensive model of OGM development. Specifically, (1) the progression of current etiological models of OGM is reviewed; (2) developmental theory and research on autobiographical memory that have relevance for OGM are discussed; and (3) an integrative model of OGM that includes processes at psychological, biological, social, and cultural levels is proposed. Directions for future research are formulated and treatment implications derived from this perspective are addressed.     

Visual memory decay is deterministic

After observers see an object or pattern, their visual memory of what they have seen decays slowly over time. Nearly all current theories of vision assume that decay of short-term memory occurs because visual representations are progressively and randomly corrupted as time passes. We tested this assumption using psychophysical noise-masking methods, and we found that visual memory decays in a completely deterministic fashion. This surprising finding challenges current ideas about visual memory and sets a goal for future memory research: to characterize the deterministic "forgetting function" that describes how memories decay over time.     

Knowing what to remember and forget: A developmental study of cue memory in intentional forgetting

These experiments are the first to investigate children’s encoding and use of information about a memory cue in Bjork’s (1972) intentional forgetting task. In Experiment 1, children in Grades 2, 4, and 6 and college students were given cues to either remember or forget after the presentation of each picture. Recall and recognition tests of pictures and cues followed. The procedure in Experiment 2 was identical to that in Experiment 1 except that the list of presentation pictures was altered for some children (Grades 3 and 4) and adolescents (Grades 8 and 9) so that remember and forget cues were associated with particular taxonomic categories. In Experiment 3, the testing component was modified so that children (Grades 2, 3, and 4) and college students were asked to recall only the cue associated with each picture. The results indicated that (1) children as young as second graders encode the cue associated with each picture, although to a lesser extent than do college students, (2) much improvement in intentional forgetting is still occurring during adolescence, (3) only adults adequately cluster their recall by cue, (4) associating remember and forget cues with items from different categories does not increase the differentiation between cues, and (5) eliminating picture recall and recognition has minimal effects on the magnitude of cue judgments. These results suggest that children’s difficulties on intentional forgetting tasks stem, at least in part, from their poorer encoding of information about whether an item should be remembered or forgotten.     

An fMRI study of long-term everyday memory using SenseCam

We used a novel automatic camera, SenseCam, to investigate recognition memory for real-life events at a 5-month retention interval. Using fMRI we assessed recollection and familiarity memory using the remember/know procedure. Recollection evoked no medial temporal lobe (MTL) activation compared to familiarity and new responses. Instead, recollection activated diverse regions in neocortex including medial prefrontal cortex. We observed decreased activation in anterior hippocampus/ anterior parahippocampal gyrus (aPHG) at 5 months compared to a 36-hour retention interval. Familiarity was associated with greater activation in aPHG and posterior parahippocampal gyrus (pPHG) than recollection and new responses. Familiarity activation decreased over time in anterior hippocampus/aPHG and posterior hippocampus/pPHG. The engagement of neocortical regions such as medial prefrontal cortex at a 5-month delay, together with the reduced MTL activation at 5 months relative to at 36 hours is in line with the assumptions of Consolidation theory. SenseCam provides a valuable technique for assessing the processes that underlie remote everyday recognition memory.