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).     

Oscillator-based memory for serial order.

A computational model of human memory for serial order is described (OSCillator-based Associative Recall [OSCAR]). In the model, successive list items become associated to successive states of a dynamic learning-context signal. Retrieval involves reinstatement of the learning context, successive states of which cue successive recalls. The model provides an integrated account of both item memory and order memory and allows the hierarchical representation of temporal order information. The model accounts for a wide range of serial order memory data, including differential item and order memory, transposition gradients, item similarity effects, the effects of item lag and separation in judgments of relative and absolute recency, probed serial recall data, distinctiveness effects, grouping effects at various temporal resolutions, longer term memory for serial order, list length effects, and the effects of vocabulary size on serial recall. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response bias in visual serial order memory

The recency-to-primacy shift represents a major challenge for all theories that attempt to explain the effects of serial order on memory. At short retention intervals, strong recency and no primacy effects occur, but as the retention interval increases, recency is attenuated and primacy increases. In 2 experiments, 24 participants were presented with sets of 4 unfamiliar faces and were asked to state the serial position of a probe face after 0 or 10 s. The predicted recency-to-primacy shift was obtained with accuracy responses. However, the distribution of responses also showed that there was a change in response bias with retention interval. When this was corrected for, the recency-to-primacy shift was eliminated. Response bias is suggested as the underlying cause of the recency-to-primacy shift in this task.     

Adult age differences in short-term memory for serial order: Data and a model.

Age-related deficits in short-term memory have been widely reported, but reduced overall scores could reflect increased order errors, increased omissions, or increased intrusions. Different explanations for reduced short-term memory with aging lead to different predictions. In this study, young (n?=?68; M age?=?20 years) and older (n?=?99; M age?=?65 years) adults were presented with lists of letters and were asked to recall each list immediately in the correct order. Age differences in error patterns were similar for auditory and visual presentation. For example, older adults made more errors of every type, and a greater proportion of the older adults' errors were omissions. An additional condition, in which older adults were encouraged to guess, ruled out an age increase in response threshold as a full explanation for the results. The data were modeled by an oscillator-based computational model of memory for serial order. A good fit to the aging data was achieved by simultaneously altering two parameters that were interpreted as corresponding to frontal decline and response slowing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intralist distractors and recall direction: Constraints on models of memory for serial order.

The serial-order version of the theory of distributed associative memory (TODAM; S. Lewandowsky and B. B. Murdock [see PA, Vol 76:14457]) predicts that disuption of forward serial recall should leave backward recall largely unaffected. This article reports 4 experiments in which the effects of an intralist distractor task were compared for forward and backward serial recall. Regardless of whether Ss could anticipate recall direction at study, the distractor task was found to disrupt forward but not backward recall. Although the existence of that dissociation had been predicted by TODAM, the theory was unable to provide a quantitative account of the data. Instead the authors provide a retrieval-based account within the framework of temporal distinctiveness theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Autobiographical memory in schizophrenia: An examination of the distribution of memories.

Patients with schizophrenia display numerous memory impairments. Examination of autobiographical memory distribution across the life span can constrain theories of how schizophrenia affects memory. Previously, schizophrenic patients were shown to produce fewer memories from early adulthood than from childhood or the recent past (A. Feinstein, T. E. Goldberg, B. Nowlin, & D. R. Weinberger, 1998), this temporal paucity corresponding with illness onset. The current study examined this issue further using a different (noncued) method. Age-matched schizophrenic patients (n = 21) and controls (n = 21) were to freely generate 50 episodes, after which they dated these memories. Patients generated fewer memories than did controls, especially from the recent decade. When the overall lower production of memories was controlled for, the groups displayed equivalent recency effects. It was concluded that patients' paucity of memories generated from the recent decade reflects encoding or acquisition problems, which may be associated with the illness period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiple roles for time in short-term memory: Evidence from serial recall of order and timing.

Three experiments are reported that examine the relationship between short-term memory for time and order information, and the more specific claim that order memory is driven by a timing signal. Participants were presented with digits spaced irregularly in time and postcued (Experiments 1 and 2) or precued (Experiment 3) to recall the order or timing of the digits. The primary results of interest were as follows: (a) Instructing participants to group lists had similar effects on serial and timing recall in inducing a pause in recall between suggested groups; (b) the timing of recall was predicted by the timing of the input lists in both serial recall and timing recall; and (c) when the recall task was precued, there was a tendency for temporally isolated items to be more accurately recalled than temporally crowded items. The results place constraints on models of serial recall that assume a timing signal generates positional representations and suggest an additional role for information about individual durations in short-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for serial order revisited.

The critiques by D. J. Mewhort et al (see record 1994-36081-001) and J. S. Nairne and I. Neath (see record 1994-36082-001) identified at least 6 potentially serious problems with S. Lewandowsky and B. B. Murdock's (see record 1989-14457-001) Theory of Distributed Associative Memory (TODAM) model of memory for serial order. It is shown that the flaws attributed to the memory component of TODAM are less serious than claimed, whereas the problems attributed to the response selection stage necessitated a process implementation of the previously unspecified deblurring mechanism. The deblurring process, implemented by a dynamic autoassociative network, is shown to handle most of the problems identified by the critics without imperiling TODAM's ability to handle basic serial position data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A spatial modality effect in serial memory.

In 2 experiments, the authors tested whether the classical modality effect--that is, the stronger recency effect for auditory items relative to visual items--can be extended to the spatial domain. An order reconstruction task was undertaken with four types of material: visual-spatial, auditory-spatial, visual-verbal, and auditory-verbal. Similar serial position curves were obtained regardless of the nature of the to-be-remembered sequences, with the exception that a modality effect was found with spatial as well as with verbal materials. The results are discussed with regard to a number of models of short-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A production system theory of serial memory.

A theory is described that provides a detailed model of how people recall serial lists of items. This theory is based on the Adaptive Character of Thought-Rational (ACT-R) production system (J. R. Anderson, 1993). It assumes that serial lists are represented as hierarchical structures consisting of groups and items within groups. Declarative knowledge units encode the position of items and of groups within larger groups. Production rules use this positional information to organize the serial recall of a list of items. In ACT-R, memory access depends on a limited-capacity activation process, and errors can occur in the contents of recall because of a partial matching process. These limitations conspire in a number of ways to produce the limitations in immediate memory span. As the span increases, activation must be divided among more elements, activation decays more with longer recall times, and there are more opportunities for positional and acoustic confusions. The theory is shown to be capable of predicting both latency and error patterns in serial recall. It addresses effects of serial position, list length, delay, word length, positional confusion, acoustic confusion, and articulatory suppression. (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)     

Birth order and hospitalization for schizophrenia.

Among female schizophrenics admitted to Spring Grove State Hospital, Catonsville, Maryland, between 1942 and 1949 there were significantly more last-born than 1st-born individuals. Compared to 1st-born, last-born females also showed a lower degree of social competence and a higher incidence of bizarre and self-destructive behavior, raising the question of whether the differences found between the birth ranks are the result of differences in incidence of the disease process or in the prevalence of forms of symptomatology likely to lead to hospitalization. Male patients showed no overall differences in birth rank. However, when the effects of social class of origin were examined, significantly more of the 1st-born and 1st-half male patients came from working-class and last-born and last-half patients from middle-class families. The study was seen as providing firm support for the previously reported relationship between birth order and schizophrenia, especially among women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for serial order: A network model of the phonological loop and its timing.

A connectionist model of human short-term memory is presented that extends the "phonological loop" (A. D. Baddeley, see record 1986-98526-000) to encompass serial order and learning. Psychological and neuropsychological data motivate separate layers of lexical, timing, and input and output phonemic information. Connection weights between layers show Hebbian learning and decay over short and long time scales. At recall, the timing signal is rerun, phonemic information feeds back from output to input, and lexical nodes compete to be selected. The selected node then receives decaying inhibition. The model provides an explanatory mechanism for the phonological loop and for the effects of serial position, presentation modality, lexicality, grouping, and Hebb repetition. It makes new psychological and neuropsychological predictions and is a starting point for understanding the role of the phonological loop in vocabulary acquisition and for interpreting data from functional neuroimaging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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)     

Impairment of memory for spatial context in schizophrenia.

A group of 33 patients with schizophrenia were compared with control participants using a spatial memory task in which words were presented on locations of a grid. In the first part of the experiment, recognition of target information (words) was tested. In the second, 2 tasks of spatial location (contextual information) were given involving different sets of words placed in different locations: A location memory task (determining which word was in a particular spatial location) explored an associative form of spatial memory, and a relocation task (determining where a particular word was located) explored an associative and a nonassociative form of spatial memory. Patients were more impaired with regard to the location memory task than to the target recognition and relocation tasks. The impairment was negatively correlated with Stroop task performance. The results suggest that schizophrenia is associated with a spatial context memory deficit, which could be due to defective associations between target and spatial information. This deficit seemed to be related to frontal dysfunction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Language production and serial order: A functional analysis and a model.

In speech production, previously spoken and upcoming words can impinge on the word currently being said, resulting in perseverations (e.g., "beef needle soup") and anticipations (e.g., "cuff of coffee"). These errors reveal the extent to which the language-production system is focused on the past, the present, and the future and therefore are informative about how the system deals with serial order. This article offers a functional analysis of serial order in language and develops a general formal model. The centerpiece of the model is a prediction that the fraction of serial-order errors that are anticipatory, as opposed to perseveratory, can be closely predicted by overall error rate. The lower the error rate, the more anticipatory the errors are, regardless of the factors influencing error rate. The model is successfully applied to experimental and natural error data dealing with the effects of practice, speech rate, individual differences, age, and brain damage. (PsycINFO Database Record (c) 2011 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)