Absence of adult age differences in forgetting in the Brown-Peterson Task

Despite some recent evidence to the contrary, no reliable age differences in proactive interference (PI) or retroactive interference (RI) were found in a cross-sectional study of adults aged 18-29 and 63-75. Individual memory span was used as the list length in the Brown-Peterson Task in order to achieve stimulus equivalence of memory loads across individuals and age groups. Data from rehearsers were excluded from the analyses in order to isolate age differences in passive forgetting processes from those in rehearsal. PI was manipulated by presenting categorized or uncategorized memory lists. RI was manipulated, holding distractor task difficulty constant, by using words or tones in a signal detection distractor task. It is concluded that age differences are minimal to nonexistent in passive RI-related processes such as decay and perturbation and in passive PI-related processes such as set effects in semantic encoding.     

The effect of word length in short-term memory: Is rehearsal necessary?

Three experiments investigated the effect of word length on a serial recognition task when rehearsal was prevented by a high presentation rate with no delay between study and test lists. Results showed that lists of short four-phoneme words were better recognized than lists of long six-phoneme words. Moreover, this effect was equivalent to that observed in conditions in which there was a delay between lists, thereby making rehearsal possible in the interval. These findings imply that rehearsal does not play a central role in the origin of the word length effect. An alternative explanation based on differences in the degree of retroactive interference generated by long and short words is proposed.     

The effect of word length in short-term memory: Is rehearsal necessary?

Three experiments investigated the effect of word length on a serial recognition task when rehearsal was prevented by a high presentation rate with no delay between study and test lists. Results showed that lists of short four-phoneme words were better recognized than lists of long six-phoneme words. Moreover, this effect was equivalent to that observed in conditions in which there was a delay between lists, thereby making rehearsal possible in the interval. These findings imply that rehearsal does not play a central role in the origin of the word length effect. An alternative explanation based on differences in the degree of retroactive interference generated by long and short words is proposed.     

Short-term retention of tactile stimulation

In three experiments subjects were required to reproduce after varying delays the locus of a tactile stimulation delivered to the upper-side of the arm. During the retention periods subjects either performed a subsidiary, arithmetic task or rested. Recall, as measured by accuracy in reproducing the locus of stimulation, decreased as a function of retention interval, asymptoting after approximately 5 s. Performance was poorer in the subsidiary task condition than in the rest condition; however, the effect of the subsidiary task appeared to be more on subject recall strategies than on rehearsal capacity. No evidence of proactive interference effects was found, and a decay interpretation of forgetting of discrete tactile stimuli in the short-term memory distractor paradigm was favoured.     

Encoding strategy and retroactive interference in short-term memory

Abstract.— The effect of encoding strategy upon retroactive interference in STM was studied. The subjects were presented two trigrams for retention with the Brown-Peterson method. In half the cases they were to recall both trigrams, in half to recall only the first. The results showed higher recall with the associative than with the rehearsal strategy. An increase in level of retroactive interference was found to increase number of retroactive interference errors in the rehearsal strategy condition and number of omissions in the associative strategy condition. The results were interpreted in terms of the memory trace integration hypothesis.     

Item Interference and Time Delays in Working Memory: Immediate Serial Recall

Limitations on immediate recall span have been related by some to temporal limitations of an articulatory rehearsal loop (Baddeley, 1986), and by others to retroactive interference from subsequent items (Lewandowsky & Murdock, 1989; Neath & Nairne, 1995). In the current study, the number of intervening items and retention delays were partially decoupled by varying presentation rate and materials sets. Recently, memory span effects often attributed to temporal limits in rehearsal were shown to be directly related to the output delays during the act of recall (Dosher & Ma, 1998). A functional model of working memory provides a framework within which to evaluate the relative contributions of item interference and retention delays in the accuracy of recall at each serial position. Output delays during recall and interference from items during study were the primary factors in limiting recall, with small additional effects of time delays during study.     

Dissociation of short-term forgetting from the passage of time

In many theories, forgetting is closely linked to the passage of time. In the present experiments, recall in a short-term memory task was less accurate when the retention interval included a difficult arithmetic addition task, compared with an easy task. In a novel condition, the interfering task was switched from hard to easy partway through the retention interval. Recall accuracy at long retention intervals recovered from the level consistent with the hard interfering task to a more accurate level consistent with an easy interfering task. Such recovery is not in agreement with theories that link forgetting to the passage of time, such as trace decay. The reversed forgetting functions are more consistent with an account in which different levels of nonspecific retroactive interference in the retention interval just before the time of retrieval influence different levels of performance accuracy. With the uncoupling of interference levels from time, forgetting is dissociated from the passage of time.     

Auditory and visual serial position functions obey different laws

Rhesus monkeys were tested in serial probe recognition tasks with either travel slide pictures or natural sounds. Tests with four-item lists produced serial position functions that were essentially opposite in shape for the two modalities and changed in opposite ways with retention interval. For visual memory, the primacy effect grew and the recency effect dissipated with retention interval. Capuchin monkeys, humans, and pigeons showed similar results. For auditory memory with rhesus monkeys, the recency effect grew and the primacy effect dissipated with retention interval. These results taken together, along with results from rehearsal tests of monkeys and humans, implicate two passive memory processes with different time courses. Interference among items within auditory lists was manipulated by varying the time between items and categories of items. Interference across lists was manipulated by varying the item pool size and, hence, item repetitions. Changes in the auditory serial position functions indicated that proactive and retroactive interference may have been instrumental in these dynamically changing serial position functions. Implications for theories and models of memory are discussed.     

Age Differences in Performance on Two Versions of the Brown-Peterson Task

The reports regarding whether normal aging is associated with faster forgetting in the Brown-Peterson task have been conflicting. We hypothesized that, in light of documented age differences on other tasks involving secondary memory, older adults would show disproportionate forgetting on the Brown-Peterson task as retention interval lengthens. Previous negative results might be a function of the specific experimental procedure used. Experiment 1, using a commonly employed procedure, did not indicate an age-related increase in rate of forgetting. This procedure allowed for differences in rehearsal opportunity, task difficulty, and amount of information to be processed. Experiment 2 controlled for these factors and did reveal significant age differences in the forgetting function. This age difference occurred only at the point where recall became dependent upon secondary memory. There was, however, no evidence of an age-related increase in rate of forgetting from primary memory in either experiment. These findings have implications for theories of cognitive aging as well as for the use and interpretation of a commonly used version of the Brown-Peterson task.     

Memory Without Consolidation: Temporal Distinctiveness Explains Retroactive Interference

Is consolidation needed to account for retroactive interference in free recall? Interfering mental activity during the retention interval of a memory task impairs performance, in particular if the interference occurs in temporal proximity to the encoding of the to‐be‐remembered (TBR) information. There are at least two rival theoretical accounts of this temporal gradient of retroactive interference. The cognitive neuroscience literature has suggested neural consolidation is a pivotal factor determining item recall. According to this account, interfering activity interrupts consolidation processes that would otherwise stabilize the memory representations of TBR items post‐encoding. Temporal distinctiveness theory, by contrast, proposes that the retrievability of items depends on their isolation in psychological time. According to this theory, information processed after the encoding of TBR material will reduce the temporal distinctiveness of the TBR information. To test between these accounts, implementations of consolidation were added to the SIMPLE model of memory and learning. We report data from two experiments utilizing a two‐list free recall paradigm. Modeling results imply that SIMPLE was able to model the data and did not benefit from the addition of consolidation. It is concluded that the temporal gradient of retroactive interference cannot be taken as evidence for memory consolidation.     

Short-term temporal changes in free recall

An experimental study of short-term memory for lists of familiar English words is reported. Lists of 10, 20, and 30 unrelated words were presented at a 1-sec. rate. Retention was measured by free recall after intervals of 0, 15 and 30 sec. A counting task was used to prevent rehearsal during the retention interval. The absolute level of recall increased with length of list whereas the percentages retained showed the reverse trend. The recall scores decreased steadily as a function of retention interval, with the rates of forgetting comparable for the three lengths of list. The decline in the amount recalled was due in large measure to the loss of the terminal items in the list. Consequently, the pronounced recency effect present on the immediate test of recall was progressively reduced as a function of time. By contrast retention of the initial part of the list was relatively stable. These variations in rate of forgetting are attributed to differences among serial positions in susceptibility to proactive inhibition.     

Retroactive and proactive interference effects in dual learning of blissymbolics and manual sign

Nonspeech systems can be either aided or unaided. Each system possesses its unique learning and memory characteristics. One instructional strategy designed to give learners the advantages of both systems is dual instruction in aided and unaided communication. One problem with this approach, however, might be that of retroactive and proactive interference in learning and memory. The current experiment investigated whether dual instruction in Blissymbolics and manual (ASL) sign would lead to retroactive and proactive interference. Lists of sign/symbol referents in the two systems were taught, to nonhandicapped adults in a controlled setting. No effects of retroactive or proactive interference were found. Additionally, a proactive facilitation effect was found for immediate retention. Results are discussed in terms of the nature of the task, the learning memory attributes of the nonspeech systems, and the effects of sign/symbol translucency.     

The Socioeconomic Status,Intelligence, and Psychometric Pattern of Native-Born White Homeless Men

Build-up of proactive interference (PI) with visual-picture and auditory-verbal input modalities and the subsequent release from PI following a change in modality was investigated in three experiments with boys and girls, as follows: Experiment I (n = 64) at two mean age levels, 7–6 and 10–5; Experiment II (n = 64) at mean age 7–6; and Experiment III (n = 48) at age 11–4. PI build-up occurred in both modalities for all ages tested. Release from PI occurred following a change from auditory to visual input but not following a visual to auditory shift. In the final experiment, this asymmetrical improvement in performance was dependent upon an interaction between the modality of the input and distractor task on the final or release trial; changing to visual input produced a release effect regardless of the distractor task modality, while auditory input was associated with improvement in recall if a visual distractor task was employed whether or not a shift in input modality had occurred. This improvement was hypothesized to represent a decrease in retroactive interference rather than a release from proactive interference.     

The development of organized rehearsal

The purpose of this research was to evaluate the development or organization strategies in rehearsal processes. First-grade (age 7 years), third-grade (age 9 years), and fifth-grade (age 11 years) children were exposed to a memory task which involved multiple overt rehearsal and recall phases. The children were either free to rehearse any words from a taxonomically structured list or they were taught to rehearse in categories. The recall phase was either free or categorically cued. The number of repetitions in rehearsal increased only as a function of age. All of the independent variables facilitated the amount of organized rehearsal and the amount of retention. Children at all ages were able to maximize the relative amount of organized rehearsal when rehearsal was cued. The correlational analysis of the dependent variables indicated that for young children the quantity of rehearsal was linked to retention, but for older children the quality of rehearsal was related to retention. The results were interpreted as demonstrating the bases for production inefficiencies.     

Long-term memory of color stimuli in the jungle crow (Corvus macrorhynchos)

Wild-caught jungle crows (n = 20) were trained to discriminate between color stimuli in a two-alternative discrimination task. Next, crows were tested for long-term memory after 1-, 2-, 3-, 6-, and 10-month retention intervals. This preliminary study showed that jungle crows learn the task and reach a discrimination criterion (80% or more correct choices in two consecutive sessions of ten trials) in a few trials, and some even in a single session. Most, if not all, crows successfully remembered the constantly reinforced visual stimulus during training after all retention intervals. These results suggest that jungle crows have a high retention capacity for learned information, at least after a 10-month retention interval and make no or very few errors. This study is the first to show long-term memory capacity of color stimuli in corvids following a brief training that memory rather than rehearsal was apparent. Memory of visual color information is vital for exploitation of biological resources in crows. We suspect that jungle crows could remember the learned color discrimination task even after a much longer retention interval.     

Combined effect of context change and retention interval on interference in causality judgments

Four experiments studied the effects of context change and retention interval on retroactive interference in human causal learning. Experiment 1 found evidence of retroactive interference. Experiment 2 found that either a 48-hr retention interval or a change in the context after the interference treatment decreased retroactive interference. An interaction between context change and retention interval effects was also found, eclipsing the context change effect after the 48-hr retention interval. Experiments 3 and 4 found additivity between context change and retention interval effects when participants were remained of the difference between physical contexts before the test, independently of whether the context change involved a return to the original acquisition context. These results add to the evidence suggesting that spontaneous forgetting is caused by a change in either the physical or the temporal contexts where information is acquired.     

Direct and indirect memory tests: What they reveal about age differences in interference

The effects of interference on memory in younger and older adults were examined in a series of three experiments. In the study task, subjects were presented with a series of sentences, each having both a target, to-be-remembered ending, and a nontarget ending. Older adults showed equal priming of targets and nontargets on an indirect memory test (Experiment 1), whereas younger adults showed greater priming of the targets. In contrast, on direct memory tests (Experiments 2 and 3) both age groups were more accurate for targets than nontargets. This pattern of results is interpreted as evidence that age differences in interference involve selective attention mechanisms, but not elaborative rehearsal processes.     

Is the word length effect in STM entirely attributable to output delay? Evidence from serial recognition

Although it is generally accepted that the word length effect in short-term memory operates through output delay or interference, there is less agreement on whether it also influences performance through its impact on rehearsal. We investigated this issue by studying the effect of word length on recall and on a recognition task in which output delay was controlled. Word sequences were repeated exactly, or with one pair of words reversed. Two experiments using auditory presentation showed clear word length effects for both recall and serial recognition, although the magnitude of the effect tended to be less for recognition. A third experiment using visual presentation studied the effect of articulatory suppression during the recognition test; again we found a clear word length effect. It is concluded that the word length effect can influence retention through both rehearsal and output factors, as proposed by the phonological loop hypothesis.     

An analysis of passive memory in normal and mentally retarded persons

The differential short-term retention of normal and mentally retarded persons is often attributed to differences in strategic functioning. There is, however, evidence for memory differences between these groups on tasks which minimize cognitive strategies. Many of the passive memory studies have been plagued with methodological and interpretative difficulties. The present experiment was an attempt to avoid these problems and clarify the possibility of passive memory differences.It was necessary to equate initial learning and control for rehearsal to compare the passive memory of normal and retarded persons across short, rehearsal-free intevals. The retention intervals were filled with a tonal detection task intended to prevent rehearsal.CA matched normal and retarded adolescents were required to recall sequences of consonants after periods of 0,9, and 27 sec. of tonal detection. These subjects also performed the detection task without the recall requirement over the same intervals. Subjects were classified as rehearsers and nonrehearsers, depending upon variations in their tonal detection accuracy, or response times across the two conditions. The main result was that normal and retarded nonrehearsers showed equal forgetting over the retention intervals.