Modality effects in short-term verbal memory.

Argues that for short-term memory, auditory presentation is consistently superior to visual presentation, with the difference restricted to recently presented items. A review of the literature indicates that recall increases with fast presentation rates when auditory presentation is used in a serial recall task; otherwise, recall decreases as presentation rate increases. Some puzzling findings on dichotic and bisensory split-span memory are shown to be related to aspects of the modality difference, notably the strong sequential associations in auditory memory. (116 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Word-frequency and phonological-neighborhood effects on verbal short-term memory.

Immediate memory span and maximal articulation rate were assessed for word sets differing in frequency, word-neighborhood size, and average word-neighborhood frequency. Memory span was greater for high- than low-frequency words, greater for words from large than small phonological neighborhoods, and greater for words from high- than low-frequency phonological neighborhoods. Maximal articulation rate was also facilitated by word frequency, phonological-neighborhood size, and neighborhood frequency. In a final study all 3 lexical variables were found to influence the recall outcome for individual words. These effects of phonological-word neighborhood on memory performance suggest that phonological information in long-term memory plays an active role in recall in short-term-memory tasks, and they present a challenge to current theories of short-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age of acquisition: Its neural and computational mechanisms.

The acquisition of new skills over a life span is a remarkable human ability. This ability, however, is constrained by age of acquisition (AoA); that is, the age at which learning occurs significantly affects the outcome. This is most clearly reflected in domains such as language, music, and athletics. This article provides a perspective on the neural and computational mechanisms underlying AoA in language acquisition. The authors show how AoA modulates both monolingual lexical processing and bilingual language acquisition. They consider the conditions under which syntactic processing and semantic processing may be differentially sensitive to AoA effects in second-language acquisition. The authors conclude that AoA effects are pervasive and that the neural and computational mechanisms underlying learning and sensorimotor integration provide a general account of these effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In search of decay in verbal short-term memory.

Is forgetting in the short term due to decay with the mere passage of time, interference from other memoranda, or both? Past research on short-term memory has revealed some evidence for decay and a plethora of evidence showing that short-term memory is worsened by interference. However, none of these studies has directly contrasted decay and interference in short-term memory in a task that rules out the use of rehearsal processes. In this article the authors present a series of studies using a novel paradigm to address this problem directly, by interrogating the operation of decay and interference in short-term memory without rehearsal confounds. The results of these studies indicate that short-term memories are subject to very small decay effects with the mere passage of time but that interference plays a much larger role in their degradation. The authors discuss the implications of these results for existing models of memory decay and interference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two separate verbal processing rates contributing to short-term memory span

Previous research indicates that verbal memory span, the number of words people can remember and immediately repeat, is related to the fastest rate at which they can pronounce the words. This relation, in turn, has been attributed to a general or global rate of information processing that differs among individuals and changes with age. However, the experiments described in this article showed that the rates of 2 processes (rapid articulation and the retrieval of words from short-term memory) are related to memory span but not to each other. Memory span depends on a profile of processing rates in the brain, not only a global rate. Moreover, there appears to be only a partial overlap between the rate variables that change with age and those that differ among individuals.     

Functional equivalence of verbal and spatial information in serial short-term memory.

Performance on a test of serial memory for the spatial position of a sequence of dots showed similarities to typical results from the serial recall of verbal material: a marked increase in error with increasing list length, a modest rise in error as retention interval increased, and bow-shaped serial position curves. This task was susceptible to interference from both a spatial task (rote tapping) and a verbal task (mouthed articulatory suppression) and also from the presence of irrelevant speech. Effects were comparable to those found with a serial verbal task that was generally similar in demand characteristics to the spatial task. As a generalization, disruption of the serial recall of visuospatial material was more marked if the interference conditions involved a changing sequence of actions or materials, but not if a single event (tap, mouthed utterance, or sound) was repeated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual and verbal short-term memory deficits in childhood leukemia survivors after intrathecal chemotherapy

Assessed survivors of childhood lymphoblastic leukemia (ALL) treated with intrathecal chemotherapy, using the Wide Range Assessment of Memory and Learning (WRAML), compared to controls without cancer, matched as closely as possible in age, SES, and gender. Mild, but consistent, deficits were found in both visual-spatial and verbal single-trial memory tasks. In multitrial learning, only visual-spatial tasks resulted in deficient scores, while verbal learning was within the normal range. IQ results indicated scores 10-20 points lower in the ALL group. Memory results are related to deficits in strategic planning and attentional distractiveness. The WRAML may be a useful clinical tool to evaluate differential memory deficits in children with ALL.     

Do two separate speech measures contrain verbal short-term memory in children?

Previous research has indicated that 2 processing rates may constrain verbal short-term memory performance. These have been linked to individual differences in (a) the time taken to articulate spoken words and (b) the duration of pauses that occur between words in the output responses to memory tasks. Two experiments examined whether evidence for these effects on memory can be obtained for measures taken from a single speech sample. Children articulated pairs of words as rapidly as possible. In both experiments, the spoken duration of words and the length of the pauses between them predicted significant variance in verbal short-term memory performance. It is argued that the duration of words is linked to memory performance through the processes underlying time-based forgetting in short-term memory. In contrast, the duration of pauses in speeded articulation may index individual differences in speech planning processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling the neural substrates of associative learning and memory: A computational approach.

We develop a computational model of the neural substrates of elementary associative learning, using the neural circuits known to govern classical conditioning of the gill-withdrawal response of Aplysia. Building upon the theoretical efforts of Hawkins and Kadell (1984), we use this model to demonstrate that several higher order features of classical conditioning could be elaborations of the known cellular mechanisms for simple associative learning. Indeed, the current circuit model robustly exhibits many of the basic phenomena of classical conditioning. The model, however, requires a further assumption (regarding the form of the acquisition function) to predict asymptotic blocking and contingency learning. In addition, if extinction is mediated by the nonassociative mechanism of habituation—rather than the associative process postulated by Rescorla and Wagner (1972)—then we argue that additional mechanisms must be specified to resolve a conflict between acquisition and maintenance of learned associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Motor skills have diverse neural bases: Spared and impaired skill acquisition in Huntington's disease.

The striatum contributes to the learning of some, but not all, motor skills. The researchers suggest that the striatum plays a role when participants learn a repeating sequence of movements, but it does not contribute when they learn a new mapping between perceptual cues and the appropriate motor response. The researchers tested patients with striatal damage due to Huntington's disease (HD) on 2 versions of a tracking task. In 1 task, the target moved randomly, allowing participants to learn the relationship between the joystick and cursor. Patients showed normal learning. In the other task, the target moved in a repeating pattern, and participants could improve performance by learning the repeating sequence of movements necessary to track the pattern. Patients were impaired on this task. Learning sequences is impaired in HD, whereas learning new mappings between perceptual cues and responses is not. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Syntactic form, semantic complexity, and short-term memory: Influences on children's acquisition of new linguistic structures.

30 children at 5 age levels (2–6 yrs) were exposed to novel actions involving 1, 2, or 3 semantic features. Simultaneously, they were taught novel labels for these actions. The labels marked the semantic features syntactically, with either a suffix, a prefix, or both a suffix and a prefix. In posttests Ss had to either supply the appropriate label for an action or produce an appropriate action for a label. Results show that (a) semantic complexity affected the difficulty of producing actions but not labels, (b) syntactic complexity affected the difficulty of producing labels but not actions, (c) there was an age below which little learning was evident on either test, (d) short-term memory (STM) was a better predictor of performance than was age, and (e) the STM value associated with each item corresponded approximately to the number of features, syntactic or semantic, that had to be processed to produce the form in question. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vocabulary performance of short-term and long-term schizophrenics.

"The following three measures of vocabulary performance varying in sensitivity were obtained from groups of short-term schizophrenics, long-term schizophrenics, and normals equated for art and education: gesticulation (nonverbal), conventional vocabulary achievement, and level of verbal communication. No differences were found between the short-term schizophrenics and the normals of any of the measures. The long-term schizophrenics were significantly lower than normals and short-term schizophrenics on all of the measures. The decrement on gesticulation for the long-term schizophrenics was significantly less than that for the other measures." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of word co-occurance on short-term memory: Associative links in long-term memory affect short-term memory performance.

In immediate serial recall tasks, high-frequency words are recalled better than low-frequency words. This has been attributed to high-frequency words' being better represented and providing more effective support to a redintegration process at retrieval (C. Hulme et al., 1997). In studies of free recall, there is evidence that frequency of word co-occurrence, rather than word frequency per se, may explain the recall advantage enjoyed by high-frequency words (J. Deese, 1960). The authors present evidence that preexposing pairs of low-frequency words, so as to create associative links between them, has substantial beneficial effects on immediate serial recall performance. These benefits, which are not attributable to simple familiarization with the words per se, do not occur for high-frequency words. These findings indicate that associative links between items in long-term memory have important effects on short-term memory performance and suggest that the effects of word frequency in short-term memory tasks are related to differences in interitern associations in long-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Separate neural bases of two fundamental memory processes in the human medial temporal lobe

The participation of medial temporal-lobe structures in memory performance was examined by functional magnetic resonance imaging of local blood oxygenation level-dependent signals. Signals were measured during encoding into memory complex scenes or line drawings and during retrieval from memory of previously studied line drawings or words. Encoding tasks yielded increased signals for unfamiliar information in a posterior medial-temporal region that were focused in the parahippocampal cortex. Retrieval tasks yielded increased signals for successfully remembered information in an anterior medial-temporal region that were focused in the subiculum. These results indicate that separate components of the human medial temporal-lobe memory system are active during distinct memory processes.     

Components of verbal working memory: evidence from neuroimaging

We review research on the neural bases of verbal working memory, focusing on human neuroimaging studies. We first consider experiments that indicate that verbal working memory is composed of multiple components. One component involves the subvocal rehearsal of phonological information and is neurally implemented by left-hemisphere speech areas, including Broca's area, the premotor area, and the supplementary motor area. Other components of verbal working memory may be devoted to pure storage and to executive processing of the contents of memory. These studies rest on a subtraction logic, in which two tasks are imaged, differing only in that one task presumably has an extra process, and the difference image is taken to reflect that process. We then review studies that show that the previous results can be obtained with experimental methods other than subtraction. We focus on the method of parametric variation, in which a parameter that presumably reflects a single process is varied. In the last section, we consider the distinction between working memory tasks that require only storage of information vs. those that require that the stored items be processed in some way. These experiments provide some support for the hypothesis that, when a task requires processing the contents of working memory, the dorsolateral prefrontal cortex is disproportionately activated.     

Auditory–verbal short-term memory effects of retention interval on proactive inhibition when interpolated interference is eliminated.

Three experiments examined auditory-verbal short-term memory using a visual nonverbal, high demand interpolated task, which successfully isolated modalities so as not to interfere with processing of the auditory-verbal items. Rehearsal was minimized, and errors were analyzed for evidence of proactive intrusions and intraunit interference. For 3-digit memory items, recall was excellent even after 60 sec (82%), and only 3% of all 3-digit items were forgotten for reasons other than measured interference. For 5-digit items, recall declined from 76% at 5 sec to approximately 65% at 9 sec. The only significant drop in recall after 9 sec was between 21 and 30 sec and was directly attributable to corresponding increases in proactive interference. Of all 5-digit items, only 5% were forgotten that were not accounted for by proactive intrusion or intraunit interference. The increase in proactive inhibition effects with increased retention interval is best fit by a model of short-term forgetting based on discriminability of temporal cues. (French summary) (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term and long-term verbal memory: a positron emission tomography study

Short-term and long-term retention of experimentally presented words were compared in a sample of 33 healthy normal volunteers by the [15O]H2O method with positron emission tomography (PET). The design included three conditions. For the long-term condition, subjects thoroughly studied 18 words 1 week before the PET study. For the short-term condition, subjects were shown another set of 18 words 60 sec before imaging, with instructions to remember them. For the baseline condition, subtracted from the two memory conditions, subjects read a third set of words that they had not previously seen in the experiment. Similar regions were activated in both short-term and long-term conditions: large right frontal areas, biparietal areas, and the left cerebellum. In addition, the short-term condition also activated a relatively large region in the left prefrontal region. These complex distributed circuits appear to represent the neural substrates for aspects of memory such as encoding, retrieval, and storage. They indicate that circuitry involved in episodic memory has much larger cortical and cerebellar components than has been emphasized in earlier lesion studies.     

Aging and interference in verbal working memory.

According to inhibitory views of working memory, old adults should have particular problems deleting irrelevant information from working memory, leading to greater interference effects compared with young adults. The authors investigated this hypothesis by using variations of an A-B, C-D retroactive interference paradigm in working memory with young and old adults. They used a recognition measure of memory, assessing both accuracy and reaction time. The primary finding was that senior adults consistently exhibited proportionally greater retroactive interference effects compared with young adults when interfering word pairs that had been read aloud had to be rejected. Patterns of recognition and reaction time data suggested that old adults' activation of target material is similar to young adults, but they experience sustained activation of irrelevation material that has entered working memory. Theoretical implications of these findings for inhibitory deficit (R.T. Zacks & L. Hasher, 1998) and source memory deficit accounts of cognitive aging are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extraversion, verbal learning, and memory.

Reviews the literature relating extraversion and human learning and memory. There appear to be several replicable differences in learning and memory between introverts and extraverts. Current theorizing emphasizes the concept of arousal and indicates that most of the obtained results are consistent with the notion that introverts are more chronically aroused than extraverts. While this approach appears to be a valuable one, several difficulties with such theorizing are noted. A major inadequacy in the work in this area is seen as the relative failure to use current advances in our understanding of the processes of storage and retrieval in the design of experiments and the subsequent interpretation of the results. (21/2 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)