Mixed-handedness advantages in episodic memory obtained under conditions of intentional learning extend to incidental learning

The existence of handedness differences in the retrieval of episodic memories is well-documented, but virtually all have been obtained under conditions of intentional learning. Two experiments are reported that extend the presence of such handedness differences to memory retrieval under conditions of incidental learning. Experiment 1 used Craik and Tulving's (1975) classic levels-of-processing paradigm and obtained handedness differences under incidental and intentional conditions of deep processing, but not under conditions of shallow incidental processing. Experiment 2 looked at incidental memory for distracter items from a recognition memory task and again found a mixed-handed advantage. Results are discussed in terms of the relation between interhemispheric interaction, levels of processing, and episodic memory retrieval.

Are numbers special? Comparing the generation of verbal materials from ordered categories (months) to numbers and other categories (animals) in an fMRI study

Months, days of the week, and numbers differ from other verbal concepts because they are ordered in a sequence, whereas no order is imposed on members of other categories, such as animals or tools. Recent studies suggest that numbers activate a representation of their quantity within the intraparietal sulcus (IPS) automatically, that is, in tasks that do not require the processing of quantity. It is unclear, however, whether ordered verbal materials in general and not only numbers activate the IPS in such tasks. In the present functional magnetic resonance imaging study word generation of months, numbers, and animals were compared. Word generation of numbers and nonnumerical materials from an ordered category (months) activated the IPS more strongly than generating items from a not-ordered category such as animals or the verbal control conditions. An ROI analysis of three subregions within the anterior IPS revealed that the most anterior and lateral of these regions, human intraparietal area hIP2, shows a greater sensitivity to ordered materials than the other two areas, hIP1 and hIP3. Interestingly, no difference in activation was observed within the IPS between numbers and months suggesting that the activation of the IPS might not be modulated by the additional quantity information carried by numbers.

Executive Control and Learning Pattern on the CVLT

We evaluated a 23 year-old man after recovery from encephalitis. In contrast to the expected pattern of increasingly better acquisition across the 5 learning trials of the California Verbal Learning Test (CVLT-2), he produced a "J-shaped" curve (Trials 1-5: 8,6,6,9,11). Because he also demonstrated excessive levels of proactive interference as well as poor divided attention, we hypothesized that his atypical learning pattern was due to a build-up of proactive interference secondary to executive dyscontrol. Using a large sample of 4462 healthy adult men, we identified four groups exhibiting various learning patterns. We found that a learning pattern similar to this patient (i.e., a drop after trial 1 followed by recovery) was rare (1.1% of the sample). Individuals with this learning pattern demonstrated increased perseverative responses, as well as greater difficulty maintaining cognitive set on the Wisconsin Card Sorting Test, decreased attentional control on the Paced Auditory Serial Addition Test, and greater levels of proactive interference on the CVLT. Taken together, the results of the study suggest that an early drop, followed by a recovery in learning trial performance, is associated with executive dyscontrol.

Intersentential syntactic context effects on comprehension: the role of working memory

The study investigated the influence of a syntactically biasing context sentence on the processing of syntactically complex object-first relative clauses and even more complex object-first complement clauses in readers with individual differences in working memory. Behavioral as well as brain responses (event-related potentials, ERPs) were recorded from two groups of participants with either a high or a low working memory span. The behavioral data taken from a post-sentence comprehension question task indicate an intersentential syntactic contextual influence on the comprehension of object-first relative clauses for low span readers, but not for high span readers. The on-line ERP measures taken at the disambiguating item revealed for the high span readers a main effect of structure (subject- versus object-first) i.e., a P600, independent of context. Low span readers, in contrast, did not show any P600 structure effect. Thus, the combined data indicate a differential context effect on sentence comprehension in low and high span readers. High span readers parse the incoming information independent of intersentential context, whereas low span readers use the intersentential context off-line.

Contextual influence on the language production of children with speech/language impairment

To investigate the possible contextual variability of language and interaction, data from 10 children with speech/language impairment and three different types of conversational partners (a parent, a peer and a clinician) were collected. The dialogues were analyzed with respect to the characteristics of the dialogues as whole, to the dominance and the productivity of the three types of conversational partners, and to the productivity, fluency and grammatical structure of the language production of the children with speech/language impairment. Productivity was measured as mean length of utterance (MLU) in words, number of utterances, number of different words and proportion of complete and intelligible utterances. Fluency was measured as the proportion of utterances containing a maze. Grammatical structure was analysed with respect to the use of grammatical morphemes, word order patterns, the occurrence of expansions and the complexity of verb forms. Significant differences, in particular between child-child and adult-child dialogues were found. The adult-child dialogues were asymmetrical, where the adults dominated through asking many questions and talking much. The peer dialogues were more dynamic and equal. In these dialogues the children with speech/language impairment took a more active role as a conversational partner. The children produced more utterances and different words with the adult partners, but variables related to fluency and grammatical structure did not vary as a function of the conversational partner. The results imply that children with speech/language impairment practise different aspects of their communicative ability with different types of conversational partners. In particular, it is important to provide them with opportunities to interact with peers, in order for them to develop their skills as independent conversational partners.

On the discovery of novel wordlike units from utterances: an artificial-language study with implications for native-language acquisition

In 4 experiments, adults were familiarized with utterances from an artificial language. Short utterances occurred both in isolation and as part of a longer utterance, either at the edge or in the middle of the longer utterance. After familiarization, participants' recognition memory for fragments of the long utterance was tested. Recognition was greatest for the remainder of the longer utterance after extraction of the short utterance, but only when the short utterance was located at the edge of the long utterance. These results support the incremental distributional regularity optimization (INCDROP) model of speech segmentation and word discovery, which asserts that people segment utterances into familiar and new wordlike units in such a way as to minimize the burden of processing new units. INCDROP suggests that segmentation and word discovery during native-language acquisition may be driven by recognition of familiar units from the start, with no need for transient bootstrapping mechanisms.

Context effects in lexical access: a meta-analysis

The modularity hypothesis was evaluated in this review of 25 studies that investigated context effects in early lexical processing. Selection criteria restricted the review to priming studies and to studies that presented the target word before or at the end of the prime word. Meta-analysis was used to provide summary information about the 17 studies in the review for which effect sizes could be calculated. Overall, the analysis revealed a small effect of context on lexical access. Results provide a disconfirmation of the modularity hypothesis; although multiple interpretations of a word were sometimes accessed, the contextually appropriate interpretation was consistently more strongly activated. The lack of significant heterogeneity of variance suggests that the variability observed across studies was due to sampling error; however, task, timing of target presentation, meaning frequency, type of target, and type of context were identified as potential moderator variables.

Verbal working memory and sentence comprehension

This target article discusses the verbal working memory system used in sentence comprehension. We review the concept of working memory as a short-duration system in which small amounts of information are simultaneously stored and manipulated in the service of accomplishing a task. We summarize the argument that syntactic processing in sentence comprehension requires such a storage and computational system. We then ask whether the working memory system used in syntactic processing is the same as that used in verbally mediated tasks that involve conscious controlled processing. Evidence is brought to bear from various sources: the relationship between individual differences in working memory and individual differences in the efficiency of syntactic processing; the effect of concurrent verbal memory load on syntactic processing; and syntactic processing in patients with poor short-term memory, patients with poor working memory, and patients with aphasia. Experimental results from these normal subjects and patients with various brain lesions converge on the conclusion that there is a specialization in the verbal working memory system for assigning the syntactic structure of a sentence and using that structure in determining sentence meaning that is separate from the working memory system underlying the use of sentence meaning to accomplish other functions. We present a theory of the divisions of the verbal working memory system and suggestions regarding its neural basis.

[Selective use of the Eight-Word subtest in psychogeriatrics]

Performance on the Amsterdam Dementia Screening Test (ADS) and the Expanded Mental Control Test (EMCT) was examined in a consecutive sample of 204 attendants of a psychogeriatric day care department. The ADS has six subtests: picture recognition, orientation, drawing alternating sequences, category fluency, copying geometric figures, and free recall with immediate yes-no recognition of eight words. As was determined by logistic regression analysis, attentional control (EMCT), category fluency and picture recognition scores were significant predictors of verbal free recall. Recognition memory for pictures and a short orientation questionnaire (month, year, place) predicted word recognition performance. In 97% of the subjects with poor scores on EMCT and category fluency, an equally poor free recall performance was found. In those cases the incremental diagnostic value of the free recall test is doubtful. Since word recall and word recognition were conceptually related to working memory and episodic memory respectively, the two components of the verbal learning test allow detection of differential impairments of these memory systems.