Short-term implicit memory for words and nonwords.

A short-term implicit memory effect is reported and interpreted as arising within the word recognition system. In Experiment 1, repetition priming in lexical decision was determined for low-frequency words and pseudowords at lags of 0, 1, 2, 3, 4, 5, 9, and 23 intervening items. For words, a large short-term priming component decayed rapidly but smoothly over the first 3 items (8 s) to a stable long-term value. For nonwords, priming dropped to the long-term value with a single intervening item. This Lag x Lexicality interaction was replicated with a naming task in Experiment 2 and with high-frequency words in Experiment 3. Word frequency affected long-term priming but not the size or decay rate of short-term priming, dissociating the two repetition effects. In Experiment 4, an old-new decision task was used to test explicit memory. Parallel word and nonword decay patterns were found, dissociating short-term priming from explicit working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term visual memory in schizophrenics.

Hypothesized that the deficit of poor premorbid schizophrenics in backward masking is due to interference in short-term visual memory (STVM) because of the tendency to process a pattern mask as if it were a cognitive mask. The hypothesis was tested in a backward-masking picture-recognition paradigm, using data from 32 male psychiatric patients (aged 18–55 yrs) and 14 hospital personnel. The 12 good premorbid schizophrenics, 7 nonschizophrenic psychotics, and normal Ss all showed differential pattern- and cognitive-mask performance. The performances of 13 poor premorbids were equivalent on both mask types. Findings corroborate the hypothesis. It is suggested that integration of stimuli in poor premorbids' sensory storage was intact and that the disruption in processing caused by a pattern mask at 200–300 msec was due to an interference in STVM. It is concluded that the hypothesis of a deficit in perceptual organization best accounts for the apparent disruptions in poor premorbids' STVM. (70 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term memory for the timing of auditory and visual signals.

Short-term memory for the timing of irregular sequences of signals has been said to be more accurate when the signals are auditory than when they are visual. No support for this contention was obtained when the signals were beeps vs flashes (Exps 1 and 3) nor when they were sets of spoken vs typewritten digits (Exps 4 and 5). On the other hand, support was obtained both for beeps vs flashes (Exps 2 and 5) and for repetitions of a single spoken digit vs repetitions of a single typewritten digit (Exp 6) when the Ss silently mouthed a nominally irrelevant item during sequence presentation. Also, the timing of sequences of auditory signals, whether verbal (Exp 7) or nonverbal (Exps 8 and 9), was more accurately remembered when the signals within each sequence were identical. The findings are considered from a functional perspective. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of the hippocampus in sex differences in verbal memory: Memory outcome following left anterior temporal lobectomy.

The authors examined the neural and cognitive bases for sex differences in verbal memory in 57 patients who underwent left anterior temporal lobectomy (ATL) for the treatment of intractable seizures. On the California Verbal Learning Test (D. C. Delis, J. H. Kramer, E. Kaplan, & B. A. Ober, 1987), women recalled more words than men both before and after surgery, regardless of the extent of hippocampal damage. Extent of hippocampal sclerosis was related to memory loss in both men and women. Women's superiority in verbal memory appears to result in part from their use of an efficient encoding strategy. Women were more likely than men to use semantic clustering both before and after ATL, and sex differences in word recall were attenuated after scores were adjusted for semantic clustering. There was no effect of ATL on semantic clustering. Taken together, these results suggest that sex differences in verbal memory are not due to differences in the integrity of the left hippocampus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental increase in the duration of memory for tone pitch.

Examined developmental change in the duration of memory for tone pitch. In Experiment 1, the persistence of memory for pitch was examined with a 2-tone comparison task in children 6–7 and 10–12 years old and in adults. Because pitch perception differences could contaminate the measure of memory, the frequency difference between tones was adjusted for each S until a criterion level of performance was reached. In a subsequent test phase, the resulting frequency difference was maintained but the time between tones was varied. Performance deteriorated across the intertone interval more quickly in younger than in older Ss. Exp 2 demonstrated that the developmental difference in pitch memory persistence is unlikely to be based on the development of strategic processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term memory for serial order: the Start-End Model

Three solutions to the problem of serial order can be identified: chaining, ordinal and positional theories. Error patterns in serial recall from short-term memory fail to support chaining theories, yet provide unequivocal evidence for positional theories. In a new model of short-term memory, the Start-End Model (SEM), the positions of items in a sequence are coded relative to the start and end of that sequence. Simulations confirm SEM's ability to capture the main phenomena in serial recall, such as the effects of primacy, recency, list length, grouping, modality, redundant suffices, proactive interference, retention interval, and phonological similarity. Moreover, SEM is the first model to capture the complete pattern of errors, including transpositions, repetitions, omissions, intrusions, confusions, and, in particular, positional errors between groups and between trials. Unlike other positional models however, SEM predicts that positional errors will maintain relative rather than absolute position, in agreement with recent experiments (Henson, 1977).     

Inferential distance and children's memory for pictorial sequences.

Three-item pictorial sequences were shown to a total of 60 5-, 6-, and 7-yr-old children who were told to remember the events. Ss were tested subsequently on their abilities to recognize old pictures and select new pictures that were consistent with previously viewed sequences. New pictures varied in the inferential distance between them and the original sequence. All Ss judged close inferences as consistent with the sequence more often than distant inferences. In general, there was a progressive developmental improvement in accurate recognition of old items and correct discrimination of new items. This pattern of results was found for judgments based on sequential compatibility and on recognition of exact pictures. The probability of inferring new relationships from old sequences increased across the 3 age groups when correct memory for original sequences was controlled. Results indicate a developmental improvement in inferential skills beyond age-related changes in memory for premise information. Furthermore, distance of inferences is an important dimension of the stimuli that can affect memory and comprehension judgments. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term memory at the turn of the century: Mary Whiton Calkins's memory research.

Mary Whiton Calkins (1863–1930) is often mentioned in accounts of the history of memory research as the inventor of the method of paired associates as well as for her investigations of primacy, recency, frequency, and vividness in association formation. Her experimental studies over the period from 1892 to 1894 not only introduced the paired associates method but were also pioneering investigations of immediate memory that led Calkins to identify modality effects, primacy and recency effects, and a number of other phenomena rediscovered many years later. Calkins's work deserves more recognition in historical accounts of early years of experimental psychology and memory research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rat hippocampus and memory for places of changing significance.

In 3 experiments, a total of 32 inbred DA Agouti and 14 outbred Sprague-Dawley rats were tested once daily on a four-choice delayed matching-to-sample task with a water reward. Each day the correct place changed, and a single exposure to it was provided on information trials. Lesions of the hippocampal formation that involved the fornix or dorsal hippocampus bilaterally produced a severe impairment in the performance of previously trained Ss. By contrast, lesions of the ventral hippocampus did not preclude reacquisition of the place-memory task. Some otherwise impaired Ss with fornical lesions were able to find the water when aided by nonplace cues that consistently signaled reward. Reducing the number of choices from 4 to 2 did not aid the impaired Ss. Certain lesions of the hippocampal formation in the rat produce a deficit appropriately described as amnesia. The memory deficit is consistent with a role for the hippocampus in processing of place information and shows some parallels to the amnesia seen in persons with temporal lobe lesions. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term memory impairment in chronic schizophrenics.

Assessed the short-term memory capacities of 4 chronic, schizophrenic and 4 nonschizophrenic psychiatric patients who served as controls. The information to be remembered was presented both visually and verbally and was later probed for after a variable interval by either visual or verbal cues. Schizophrenics and controls did not differ with respect to which type of cue retrieved more of the information, suggesting that the modality in which the information was stored was the same for both groups. However, schizophrenics were markedly inferior to controls regarding both the initial acquisition of information and the maintenance of it in storage. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term memory in autism spectrum disorder.

Three experiments examined verbal short-term memory in comparison and autism spectrum disorder (ASD) participants. Experiment 1 involved forward and backward digit recall. Experiment 2 used a standard immediate serial recall task where, contrary to the digit-span task, items (words) were not repeated from list to list. Hence, this task called more heavily on item memory. Experiment 3 tested short-term order memory with an order recognition test: Each word list was repeated with or without the position of 2 adjacent items swapped. The ASD group showed poorer performance in all 3 experiments. Experiments 1 and 2 showed that group differences were due to memory for the order of the items, not to memory for the items themselves. Confirming these findings, the results of Experiment 3 showed that the ASD group had more difficulty detecting a change in the temporal sequence of the items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for duration: role of hippocampus and medial prefrontal cortex

In this task rats had to learn that a three-dimensional object stimulus (a rectangle) that was visible for 2 s would result in a positive (go) reinforcement for one object (a ball) and no reinforcement (no go) for a different object (a bottle). However, if the rectangle stimulus was visible for 8 s then there would be no reinforcement for the ball (no go), but a reinforcement for the bottle (go). After rats learned this conditional discrimination by responding differentially in terms of latency to approach the object, they received large (dorsal and ventral) lesions of the hippocampus, lesions of the medial prefrontal cortex (anterior cingulate and precentral cortex), lesions of the cortex dorsal to the dorsal hippocampus, or served as sham-operated controls. Following recovery from surgery they were retested. The results indicate that there were major impairments following hippocampal lesions, in contrast to cortical control and medial prefrontal cortex lesions, as indicated by smaller latency differences between positive and negative trials on postsurgery tests. In order to ensure that the deficits observed with hippocampal lesions were not due to a discrimination problem, new rats were trained in an object (gray cylinder) duration discrimination task. In this go/no go procedure, the rats were reinforced for a 2-s exposure (duration) of the gray cylinder, but not a 10-s duration, or vice versa. The results indicate that after hippocampal lesions, there was an initial deficit followed by complete recovery. There were no significant changes for the medial prefrontal, cortical control, or sham-operated animals. It appears that the hippocampus, but not the medial prefrontal cortex, is actively involved in representing in short-term memory temporal attribute information based on the use of markers for the beginning and end of the presence (duration) of a stimulus (object).     

Short-term memory for simultaneously presented visual and auditory signals in the pigeon.

Conducted 3 divided-attention experiments with 8 adult Silver King pigeons, in which matching to the visual or auditory component of a tone–light compound was compared with matching to visual or auditory elements as sample stimuli, to investigate Ss' short-term memory for simultaneously presented visual and auditory signals. In 0-sec delayed and simultaneous matching procedures, Ss were able to match visual signals equally well when presented alone or with a tone. Tones were matched at a substantially lower level of accuracy when presented with light signals than when presented as elements. The interfering effect of a signal light on tone matching was not related to the signaling value of the light, and the prior presentation of light proactively interfered with auditory delayed matching. Findings indicate a divided-attention process in which auditory processing is strongly inhibited in the presence of visual signals. (32 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Subjective shortening: A model of pigeons' memory for event duration.

Investigated memory for event duration using a delayed matching-to-sample procedure in 4 experiments with 10 Silver King pigeons. When a retention interval of variable length intervened between sample and comparison stimuli, Ss responded as though long samples had been short after retention intervals of 10 sec or more. This "choose-short" effect occurred whether S was naive or experienced, whether sample durations were represented by food access or light, or whether a 2- or 3-choice procedure was used. A subjective-shortening model is proposed in which it is assumed that working memory of the sample duration shortens over the retention interval. Comparison of this memory with a stable reference memory produces the tendency to respond as though a long sample were short. The subjective-shortening model accounts for the following results: After a long-retention interval, psychophysical functions relating probability of choosing long to sample duration were shifted toward longer durations. Stepwise increases in the retention interval produced a temporary choose-short effect, whereas stepwise decreases produced a temporary choose-long effect. With extended training at given retention interval, the choose-short and choose-long effects diminished. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Proactive effects in pigeons' memory for event duration: Evidence for analogical retention.

An intratrial proactive interference design was used to examine the nature of pigeons' memory for duration in a delayed matching task. Short (2 s) or long (10 s) target samples were preceded on test trials by a short or long presample. The durations were consistent on some trials (short-short or long-long) and inconsistent on others (short-long or long-short). Contrary to predictions based on prospective or categorical coding, accuracy was not related to duration consistency. Instead, accuracy was reduced on short-short and long-short trials and somewhat enhanced on short-long and long-long trials, suggesting that the Ss "summed across" the durations. This occurred even with a 10-s interstimulus interval (Experiment 1) and even when the presample and target sample were physically distinct (Experiment 2). Results suggest that pigeons remember event durations in an analogical and retrospective fashion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Double dissociation of function within the hippocampus: Spatial memory and hyponeophagia.

Complete and dorsal hippocampal lesions impaired spatial performance on 2 working memory tasks: rewarded alternation on the T maze and matching to position in the water maze. In contrast, ventral hippocampal lesions had no effect on these tasks, even when task difficulty was increased by the introduction of delays. Ventral lesions did resemble complete lesions in reducing anxiety in 3 commonly used tests of anxiety (social interaction, plus-maze, and hyponeophagia). Dorsal lesions also appeared to be anxiolytic in the social interaction and plus-maze tests, but they did not affect hyponeophagia. Complete- and dorsal-lesioned rats displayed hyperactivity, whereas ventral-lesioned rats did not. These results show a double dissociation between dorsal and ventral hippocampal lesions (hyponeophagia vs. spatial memory), suggesting differentiation of function along the septotemporal axis of this structure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Growth points in research on memory and hippocampus.

We present an overview of two of our ongoing projects relating processes in the hippocampus to memory. We are trying to understand why retrograde amnesia occurs after damage to the hippocampus. Our experiments establish the generality of several new retrograde amnesia phenomena that are at odds with the consensus view of the role of the hippocampus in memory. We show in many memory tasks that complete damage to the hippocampus produces retrograde amnesia that is equivalent for recent and remote memories. Retrograde amnesia affects a much wider range of memory tasks than anterograde amnesia. Normal hippocampal processes can interfere with retention of a long-term memory stored outside the hippocampus. We conclude that the hippocampus competes with nonhippocampal systems during memory encoding and retrieval. Finally, we outline a project to understand and manipulate adult hippocampal neurogenesis in order to repair damaged hippocampal circuitry to recover lost cognitive functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term memory factor in the design of data-entry keyboards: An interface between short-term memory and S-R compatibility.

An experiment on immediate recall of an 8-digit sequence was carried out. Mode of recall was via a data-entry keyboard. 2 keyboard layouts were used, 1 of high and 1 of low compatibility. The low-compatibility keyboard required more time for entry and gave more errors. These extra errors were identified as being primarily memory rather than aiming errors. The results are discussed in terms of an interface between short-term memory and S-R compatibility; they are held to support a memory model involving a limited-capacity channel, and a practical design conclusion is suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term memory scanning in schizophrenic young adults.

Used the Sternberg item-recognition procedure to investigate the process of short-term memory scanning and recognition of common English words in 16 schizophrenics, 16 nonschizophrenic psychiatric patients, and 16 normals (college students). The S was required to respond as quickly and accurately as possible to whether a probe word matched the word or words shown a few seconds earlier. Results show that the 3 groups' response latencies increased at approximately equal rates as the memory set size increased, but the overall response latencies of both patient groups were profoundly slower than normals. All 3 groups revealed a significant serial position effect and a logarithmic reaction time function for the positive probe. No single model of the scanning strategy appears to fit straight-forwardly to the present data. It is concluded that the schizophrenics' short-term memory scanning was intact, and their slowness in response is, therefore, to be understood in terms of some dysfunction in their stimulus encoding, response selection, and/or response execution. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Activity duration and adult age differences in memory for activity performance.

30 undergraduates and 30 elderly adults (mean age 69.86 yrs) performed a series of activities that varied in the duration of their performances (45, 90, and 180 sec). Duration had a negligible effect on the subsequent recall of the activities and on the magnitude of the age deficit in recall. Operationalization of the program for performing an activity seems essential for establishing a memory trace of that activity's performance, but the duration of performing that activity seems to yield no further enhancement of that trace. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)