Ventromedial prefrontal damage and memory for context: Perceptual versus semantic features.

Memory for context is known to rely on episodic binding and strategic retrieval processes. It is unclear, however, whether memory for different contextual features taps the same cognitive and neural mechanisms. Here, the authors compare memory for a perceptual feature (i.e., the format in which an item had been presented) and for a semantic feature (i.e., the concept with which an item had been paired) in 13 patients with lesions in ventromedial prefrontal cortex, including patients with and without confabulation, and 13 healthy controls. Participants studied picture–word pairs and received an old–new recognition test that included intact pairs, rearranged pairs, format pairs (studied pairs in which the picture–word format of each item was switched), old–new pairs, and new–new pairs. Hit rates for intact pairs were similar for all participant groups. Compared with controls, patients, especially those with confabulation, had higher false-alarm rates for format pairs but comparable false-alarm rates for rearranged pairs. The authors propose that distinct monitoring processes are engaged during retrieval of perceptual and semantic context, with only the former crucially dependent on ventromedial prefrontal cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of memory activation in creating false memories of encoding context.

Using 3 experiments, I examined false memory for encoding context by presenting Deese–Roediger–McDermott themes (Deese, 1959; Roediger & McDermott, 1995) in usual-looking fonts and by testing related, but unstudied, lure items in a font that was shown during encoding. In 2 of the experiments, testing lure items in the font used to study their associated themes increased false recognition relative to testing lure items in a font that was used to study a different lure’s theme. Further, studying a larger number of associates exacerbated the influence of testing lure items in a font used to study their associated themes. Finally, testing lures in a font that was encoded many times, but was not used to present the lures’ studied associates, increased lure errors more than testing lures in a font that was encoded relatively fewer times. These results favor the explanation of false recognition offered by global-matching models of recognition memory over the explanations of activation-monitoring theory and fuzzy-trace theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of context on the immediate interpretation of unambiguous nouns.

Effects of prior sentential context on the interpretation of unambiguous nouns were investigated in 2 cross-modal priming experiments. Exp 1 showed that a prior priming context affects word interpretation during lexical access by facilitating the recovery of contextually relevant aspects of meaning and inhibiting the recovery of irrelevant aspects. Exp 2 showed that lexical decision on a visual word related to an aspect of meaning of an unambiguous noun is facilitated only by a sentential context containing the noun and priming that aspect. Such facilitation occurs neither when the unambiguous noun is replaced by a substitute noun in the same sentential context, nor when the unambiguous noun occurs in a sentence priming an aspect of its meaning unrelated to the visual word. Furthermore, neither of these 2 conditions produced effects on lexical decision reliably different either from each other or from a sentential context completely unrelated to the visual word. Findings argue against the context-independent model of lexical access and support the hypothesis that lexical access may be affected by prior sentential context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An investigation of the role of working memory in procedural skill acquisition.

On the basis of the ACT* production system theory of skill acquisition (Anderson, 1983a, 1987), I generated predictions concerning the role of two proposed classes of working-memory limitations in procedural learning. Individual differences analyses of a laboratory procedural learning task tested these predictions. As hypothesized, measures of controlled attention in working memory predicted initial declarative rule acquisition and proceduralization, and measures of automatic activation in working memory predicted indexes of later production composition and strengthening. Results supported a distinction between two working-memory capacity constructs that impose unique limits on processes of skill acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental differences in episodic retrieval: The role of differences in concept representations in semantic memory.

Developmental differences in the relative salience of features in concept representations in semantic memory and their contributions to differences in cued recall were examined in two experiments. For second graders, fifth graders, and college students, acquisition encoding of cue–target noun pair information was constrained by means of defining-, characteristic-, category-, and incidental-feature orienting questions. At retrieval, the encoding of cue information alone was constrained (Experiment 1) within subjects by means of the same (e.g., defining at acquisition and defining at retrieval) or related (e.g., defining at acquisition and characteristic at retrieval) retrieval questions or was unconstrained (Experiment 2). In both experiments, the acquisition presentation duration was manipulated (1 s or 5 s) in order to examine the spread of feature activation within concepts. The results showed that recall varied with feature salience, with the salience greatest for defining features. In addition, the results suggested that the relative salience of defining features was at least as great for the children as for the adults. The results offer no support for Keil and Batterman's (1984) hypothesis of a shift from characteristic to defining features in the development of word meaning representation in memory. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The deterioration of semantic memory in Alzheimer's disease.

Semantic memory impairment is a common feature of dementia of the Alzheimer type (DAT). Recent research has shown that patients with DAT are more impaired (relative to non-demented controls) in generating exemplars from a particular semantic category (e.g., animals) than words beginning with a particular letter, exhibit an altered temporal dynamic during the production of category exemplars, are impaired on confrontation naming tasks and make predominantly superordinate or semantically related errors, consistently misidentify the same objects across a variety of semantic tasks, and have alterations in multidimensional scaling models of their semantic network that are indicative of a loss of concepts and associations. These results are consistent with the view that Alzheimer's disease results in a breakdown in the organization and structure of semantic knowledge as neurodegeneration spreads to the association cortices that presumably store semantic representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of context on semantic differential ratings.

Presents 3 studies testing the effect of context on semantic differential ratings. 1 view (absolutistic) considers each rating an independent judgment, which should not be affected by context. From a relativistic viewpoint, context establishes a frame of reference which should affect the ratings. This latter view would predict a decrease in the variability in rating concepts as the context shifts from homogeneous to heterogeneous to contrast conditions. Results of all 3 studies support the absolutistic position. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of psychosocial context, age, and intelligence in memory performance of older men.

Examined the hypothesis that psychosocial contextual factors contribute to developmental changes in memory using 326 World War II veterans. Availability of young adult intelligence scores made it possible to separate the contributions of contextual variables and age to maintenance of general intelligence from their direct contributions to performance on 4 memory tasks. Being younger, healthier, more educated, more introverted, more intellectually active, and more satisfied with social support predicted less intellectual decline and, indirectly, better memory performance. Age, personality, locus of control, and extent of social support directly contributed to performance on 1 or more memory tasks. Age contributions were consistent with F. I. Craik's (1986) proposed continuum of task demands for self-initiated effort. Possible elaborations of Craik's hypothesis to accommodate contextual variables are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of dorsal hippocampus and basolateral amygdala NMDA receptors in the acquisition and retrieval of context and contextual fear memories.

The authors used 3-phase context preexposure facilitation methodology to study the contribution of N-methyl-D-aspartate (NMDA) receptors in dorsal hippocampus (DH) and the basal lateral region of the amygdala (BLA) to (a) acquisition of the context memory, (b) retrieval of the context memory, (c) acquisition of context-shock association, and (d) retrieval of the context-shock association. The NMDA receptor antagonist D-2-amino-5 phosphonopentanoic acid (D-AP5) was injected into either the DH or BLA prior to (a) the context preexposure phase, (b) the immediate shock phase, or (c) the test for contextual fear. Antagonizing NMDA receptors in the DH impaired the acquisition of the context memory but did not affect its retrieval or retrieval of the fear memory. Antagonizing NMDA receptors with D-AP5 in the BLA impaired acquisition of the context-shock association but had no effect on the expression of fear. However, both DL-AP5 and L-AP5 reduced the expression of fear when they were injected into the amygdala prior to testing for contextual fear. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The salience of the centrality/peripherality dimension in semantic memory.

Tested the salience of the central/peripheral distinction in natural categories for 72 undergraduates and graduate students using a release-from-proactive-inhibition task. It was hypothesized that if the central/peripheral distinction is a meaningful one, then switching from central to peripheral items or from peripheral to central items within the same category would produce a significant release effect. This hypothesis was tested with 2 semantic categories selected from E. Rosch's (see record 1976-00172-001) centrality/peripherality norms (clothing and furniture). When Ss' performance was analyzed, no significant difference was found between switching from central to peripheral items or switching from peripheral to central items. There was also no significant difference between the 2 categories of clothing and furniture. There was, however, a significant release effect on the release trial. It appears that the central/peripheral distinction is a meaningful one for adults, as Rosch has suggested. (French abstract) (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Process complexity in semantic memory.

Are sentences verified by a lone computational mechanism, or does this mechanism race in parallel with a generally faster search of semantic memory? Rejecting either the single- or dual-process account would clarify whether semantic memory is structured or is a relatively unstructured (computational) system. This study examined verification reaction time (RT) distributions for a dissociation between fast and slow RTs due to the manipulation of semantic variables. A race between a search and a generally slower computational process should yield an RT distribution whose fastest RTs are usually determined by the search and whose slowest RTs are usually determined by computation. If a manipulation affects these 2 processes differently, the fast and slow RTs will be differentially affected. Results from 3 verification experiments support this view. Other results suggest even greater process complexity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Meaning and modality: Influences of context, semantic memory organization, and perceptual predictability on picture processing.

Using event-related potentials (ERPs), the authors investigated the influences of sentence context, semantic memory organization, and perceptual predictability on picture processing. Participants read pairs of highly or weakly constraining sentences that ended with (a) the expected item, (b) an unexpected item from the expected semantic category, or (c) an unexpected item from an unexpected category. Pictures were unfamiliar in Exp 1 but preexposed in Exp 2. ERPs to pictures reflected both contextual fit and memory organization, as do ERPs to words in the same contexts (K. D. Federmeier and M. Kutas, see record 1999-15076-002). However, different response patterns were observed to pictures than to words. Some of these arose from perceptual predictability differences, whereas others seem to reflect true modality-based differences in semantic feature activation. Although words and pictures may share semantic memory, the authors' results show that semantic processing is not amodal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conjoint and dissociable effects of syntactic and semantic context

Manipulating the semantic relatedness of noun and verb targets in contexts where they are grammatically appropriate or inappropriate allows for simultaneous examination of syntactic and semantic context effects. A lexical-decision experiment showed both a syntactic context effect and a semantic relatedness effect that was stronger in syntactically appropriate conditions. Thus, latencies appeared to be conjointly determined by syntactic and semantic context. In contrast, naming experiments also showed both semantic and syntactic effects, but the syntactic context effect was independent of semantic relatedness and was observed in the virtual absence of sensitivity to semantic anomaly. Thus, syntactic and semantic processing are largely dissociable in the naming task. In conjunction with other findings in the literature, this suggests the existence of an isolable level of syntactic assignment that precedes semantic integration of content words in sentence comprehension.     

Generation and context memory.

Generation enhances memory for occurrence but may not enhance other aspects of memory. The present study further delineates the negative generation effect in context memory reported in N. W. Mulligan (2004). First, the negative generation effect occurred for perceptual attributes of the target item (its color and font) but not for extratarget aspects of context (location and background color). Second, nonvisual generation tasks with either semantic or nonsemantic generation rules (antonym and rhyme generation, respectively) produced the same pattern of results. In contrast, a visual (or data-driven) generation task (letter transposition) did not disrupt context memory for color. Third, generating nonwords produced no effect on item memory but persisted in producing a negative effect on context memory for target attributes, implying that (a) the negative generation effect in context memory is not mediated by semantic encoding, and (b) the negative effect on context memory can be dissociated from the positive effect on item memory. The results are interpreted in terms of the processing account of generation. The original, perceptual-conceptual version of this account is too narrow, but a modified processing account, based on a more generic visual versus nonvisual processing distinction, accommodates the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult age differences in semantic and episodic memory

Cleft lip and palate occurs in approximately 1 in every 750 live human births, making it one of the most common congenital malformations. Surgical closure of the palatal cleft does not always result in a velopharyngeal port capable of supporting normal speech. The University of Florida (UF), in collaboration with the University of S?o Paulo (USP), is engaging in a 5-year prospective, randomized controlled study to compare velopharyngeal function for speech outcomes between patients undergoing palatoplasty for complete unilateral cleft lip and palate performed using the von Langenbeck procedure with intravelar velarplasty and those receiving the Furlow double-reversing Z-plasty palatoplasty. The von Langenbeck procedure was selected as the time-tested standard against which the Furlow procedure could be judged. The Furlow procedure, a relatively new operation, has been reported to yield substantially higher rates of velopharyngeal competency for speech than have most other reported series and theoretically should result in less disturbance to midfacial growth. A total of 608 patients will be entered into one of two age categories. Inclusion of two age groups will allow a comparison of results between patients having surgery before 1 year of age (9-12 months) and patients undergoing surgery at approximately 1.5 years of age (15-18 months). Speech data will be collected and will be available for definitive analysis throughout the last 3 years of the study. Collection of preliminary growth data will require more than 5 years; growth analysis is anticipated to continue until all patients have reached maturity. The Hospital for Research and Rehabilitation of Patients with Cleft Lip and Palate at the University of S?o Paulo (USP-HPRLLP) in Bauru, Brazil, is uniquely situated for conducting this study. The well-equipped and modern facilities are staffed by well-trained specialists representing all disciplines in cleft-palate management. In addition, an already existing social services network throughout Brazil will ensure excellent follow-up of study cases. The clinical caseload at this institution currently exceeds 22,000, and more than 1200 new cases are added annually. This project represents a unique opportunity to obtain prospective data from a large number of subjects while controlling the variables that have traditionally plagued cleft-palate studies. This study is designed to determine which of the two proposed surgical procedures is superior in constructing a velum capable of affecting velopharyngeal competency for the development of normal speech.     

Retrieval blocks in episodic and semantic memory.

A retrieval block (RB) refers to impaired accessibility in retrieving target information when semantically related information is presented or retrieved prior to target retrieval. A research review reveals that RBs occur in a variety of situations, including both episodic and semantic memory tasks. RBs have been most thoroughly studied in the part-list cuing paradigm in episodic recall, but similar principles seem to operate in other situations, including the A–B, A–D interference paradigm, episodic recognition, and the tip-of-the-tongue situation. Evidence for such RBs is problematic for theories postulating automatic spreading activation among associated nodes in memory. Difficulties with theories that account for such RBs are discussed. Further research on RBs may help illuminate similar phenomena, such as the effects of Einstellung in thinking and problem solving. (French abstract) (76 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of semantic encoding on recognition memory in Alzheimer's disease

Within the framework of the distinction between episodic and semantic memory, it has been argued that these two memory systems are organised in a hierarchical way. The hierarchical hypothesis assumes that episodic memory is a specific subsystem of semantic memory and therefore implies that episodic memory cannot exist without semantic memory. If this hypothesis is correct, it should be expected that patients with impaired semantic memory also have impaired episodic memory. In the present study, two experiments investigated the influence of semantic encoding on recognition memory performance in a population of 20 patients with Alzheimer's disease and 18 normal controls. Both experiments assessed recognition memory for semantically-related items. In Experiment 2, but not in Experiment 1, subjects were explicitly instructed to make a semantic association between the items. Alzheimer's disease patients were impaired, compared to the normal controls, on the recognition memory performance of both experiments. The ability to make a semantic association between two items was significantly and positively correlated with the subjects' performance on the recognition tasks. A further analysis showed that patients who were impaired on the semantic association task did significantly worse on the recognition task of Experiment 2 than normal controls and patients who were unimpaired on the semantic association task. These findings are discussed in the context of memory deficits in Alzheimer's disease, and are interpreted as supporting the view that episodic memory for an item is affected by the level of semantic awareness of that same item.     

Dynamics of activation in semantic and episodic memory.

Two experiments with the adaptive priming procedure are reported to test discrete and continuous activation models for the structure of semantic and episodic memory. In Experiment 1, the prime and test stimuli were semantically associated words (e.g., bread–butter). In Experiment 2, episodic associations between the prime and test stimuli were established through paired associate learning. For both cases, the mixture prediction failed, and 2-state activation models were rejected. We conclude that models with only 2 discrete states of activation, that is, all-or-none models, do not accurately characterize the dynamics of activation in semantic and episodic memory. Higher order discrete or continuous models may better account for the results. Our findings are consistent with several current continuous models of spreading activation. They contrast, however, with those from previous work in which response-preparation processes appeared to proceed in a discrete, all-or-none fashion (Meyer, Yantis, Osman, & Smith, 1985). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age and rate of activation in semantic memory.

Two word-primed picture-naming experiments were carried out to test the hypothesis that rate of activation in semantic memory is slower for older adults than for young adults. The presence of priming effects, both positive and negative, was taken as evidence of activation. In Exp 1 there was no age difference in the time of onset of either facilitation or inhibition by primes. A computer simulation, based on a simple connectionist model, showed that slower processing would have only a minimal effect on the time of onset of priming effects under the assumptions of the model; however, offset of inhibition by primes would be delayed if processing rate were reduced. In Exp 2 older adults showed inhibition by primes over a longer interval than did young adults, which was taken as evidence that the general slowing associated with aging extends to the transmission of activation at the earliest levels of cognitive processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)