Consolidation of multifeature items in visual working memory: Central capacity requirements for visual consolidation

In the present study, we examined whether greater attentional resources are required for consolidating two features (e.g., color and orientation) than for consolidating one feature (e.g., color) in visual working memory (WM). We used a dual-task procedure: Subjects performed a WM task and a secondary probe task, sometimes concurrently. In the WM task, subjects decided whether two displays (containing one to four objects composed of one or two features) were the same or different. In the probe task, subjects made a speeded discrimination response to a tone. Performance in both tasks was impaired when they were performed concurrently; however, performance costs in the tone task were not greater for multi- than for single-feature conditions (when the orientation and conjunction conditions were considered). Results suggested that equivalent attentional resources were necessary for consolidation of single-orientation or multifeature items.     

Effects of sleep deprivation on Color-Word, Emotional, and Specific Stroop interference and on self-reported anxiety

The aim of this study was principally to assess the impact of sleep deprivation on interference performance in short Stroop tasks (Color-Word, Emotional, and Specific) and on subjective anxiety. Subjective sleepiness and performance on a psychomotor sustained attention task were also investigated to validate our protocol of sleep deprivation. Twelve healthy young subjects were tested at four-hourly intervals through a 36-h period of wakefulness under a constant routine protocol. Analyses of variance for repeated measurements revealed that self-assessment of sleepiness on a visual analogue scale as well as mean reaction time performance on the sustained attention task, both for the first minute and for 10 min of testing, were worsened by sleep deprivation. Analyses revealed an increase in self-reported anxiety scores on the STAI questionnaire but did not reveal any significant effect after sleep deprivation either on indexes of interference or on accuracy in Stroop tasks. However, analyses showed sensitivity to circadian effect on verbal reaction times in the threat-related (Emotional) and sleep-related (Specific) Stroop tasks. We concluded that 36 h of prolonged wakefulness affect self-reported anxiety and Emotional Stroop task resulting in a cognitive slowing. Moreover, total sleep deprivation does not affect interference control in any of the three short Stroop tasks.     

Effect of bilateral stimulation of the subthalamic nucleus on parkinsonian dysarthria

Never was the effect of bilateral stimulation of the subthalamic nucleus (STN) evaluated quantitatively on all the components of speech production, that is articulation, respiration and phonation, at the same time. It is the purpose of this study which uses force measurements of the articulatory organs and acoustic analysis in 16 parkinsonian patients. With STN stimulation, reaction and movement time of the articulatory organs decreased and their maximal strength, as well as their precision increased. We also noted a large beneficial effect on voice with a significant improvement in respiratory and phonatory functions.     

Correlational analyses of explicit and implicit memory performance

Sixty-four subjects were administered two tests of explicit memory (selective recall and recognition) and four tests of implicit memory (identification in a perceptual clarification procedure, word-fragment completion, tachistoscopic identification, and anagram solution). Each test drew on a different subset of a long list of previously displayed words. Although the four implicit memory tests showed sizable priming effects, correlational and factor analyses showed striking dissociations. On the one hand, performance on the perceptual clarification procedure and word-completion tests were related to one another, as well as to recall and recognition. On the other hand, performance on tachistoscopic identification and anagram solution were related to one another, but not to the measures for the other tasks. A framework is proposed to reconcile these new results with current knowledge on the explicit/implicit memory distinction, based in particular on studies of amnesic subjects. It is argued that a small number of tasks, especially tachistoscopic identification, may serve as relatively uncontaminated and ubiquitous indicators of implicit memory. However, explicit remembering could affect performance in so-called implicit memory tasks that allow for a strategy of controlled selection of candidate responses from accumulating cues, in experimental conditions that make the explicit remembering of relevant events possible.     

Age trends in early behavioral predictors of serious antisocial behaviors

A risk group of disruptive boys (N=65) identified in kindergarten was assessed using the same procedures at ages 6–7, 8–9, and 10–11. Criteria used to define the predictors and criterion variable were the same at all assessment times. Severity was addressed by comparing different forms of behaviors, considering the extent of harmful consequences to others (aggressiveness was considered as most harmful, whereas inattention was considered as least harmful), manifestation in multiple settings, and extreme scores (manipulation of cutoff scores). Different assessment strategies (direct observations, ratings) and different informants (trained observers, mothers and teachers) were used. Aggressiveness as rated by mothers was highly stable from age 6 to age 11. Inattention as rated by teachers was stable only from age 6 to age 9, whereas no stability was found for observations of task inappropriate behaviors. Taskinappropriate behaviors observed in mother-child interactions and in multiple settings at age 6–7 were significant predictors of self-reported antisocial behaviors at age 12, but this prediction was not repeated at ages 8–9 and 10–11. Teacher ratings of inattention at ages 6–7 and 8–9 were also significant predictors of self-reported antisocial behaviors at age 12. The predictive power was much lower when mothers' ratings of aggressiveness were used. Findings from the present study support the hypothesis that some antisocial behavior precursors are age dependent, in that they are more characteristic of certain age groups than of others. Implications for the selection of assessment screening procedures are discussed.     

Cognitive discernible factors between schizophrenia and schizoaffective disorder

BACKGROUND: Schizophrenia (SZ) and schizoaffective disorders (SA) are associated with cognitive deficits. Generally, a schizoaffective diagnosis is associated with better prognosis on the level of social integration. It is also well established that cognition is an important factor for good social outcome in schizophrenia. We hypothesized that, although patients suffering from SA share symptoms with SZ, they can be differentiated on the basis of neurocognitive function and that SA perform better in several domains. METHOD: Performances of two groups SA (N = 13) and SZ (N = 44) were compared on several visual-motor tasks using CANTAB [Motor Screening (MOT), Reaction Time (RTI), Paired Associates Learning Task (PAL), and Stockings of Cambridge items (SOC)]. The two groups were matched for symptom severity. ANOVA with repeated measures was employed to determine whether any difference in cognitive scores during a 2-year period was significantly related to the diagnostic status. RESULTS: A significant and durable difference was observed between SZ and SA on motor screening and explicit memory tests where SA performed better. CONCLUSION: Neurocognitive tests may be relevant for distinguishing schizoaffective from schizophrenia, chiefly via tests tapping into visuo-spatial and visuo-motor coordination abilities (e.g., paired associated learning and motor screening).     

Does the mastery of center-embedded linguistic structures distinguish humans from nonhuman primates?

In a recentScience article, Fitch and Hauser (2004; hereafter, F&H) claimed to have demonstrated that cotton-top tamarins fail to learn an artificial language produced by a phrase structure grammar (Chomsky, 1957) generating center-embedded sentences, whereas adult humans easily learn such a language. We report an experiment replicating the results of F&H in humans but also showing that subjects learned the language without exploiting in any way the center-embedded structure. When the procedure was modified to make the processing of this structure mandatory, the subjects no longer showed evidence of learning. We propose a simple interpretation for the difference in performance observed in F&H’s task between humans and tamarins and argue that, beyond the specific drawbacks inherent in F&H’s study, researching the source of the inability of nonhuman primates to master language within a framework built around Chomsky’s hierarchy of grammars is a conceptual dead end.     

What makes working memory spans so predictive of high-level cognition?

Working memory (WM) span tasks involving a complex activity performed concurrently with item retention have proven to be good predictors of high-level cognitive performance. The present study demonstrates that replacing these complex self-paced activities with simpler but computer-paced processes, such as reading successive letters, yields more predictive WM span measures. This finding suggests that strategic factors do not contribute to be relationship between WM spans and high-level cognition.     

Time and cognitive load in working memory

According to the time-based resource-sharing model (P. Barrouillet, S. Bernardin, & V. Camos, 2004), the cognitive load a given task involves is a function of the proportion of time during which it captures attention, thus impeding other attention-demanding processes. Accordingly, the present study demonstrates that the disruptive effect on concurrent maintenance of memory retrievals and response selections increases with their duration. Moreover, the effect on recall performance of concurrent activities does not go beyond their duration insofar as the processes are attention demanding. Finally, these effects are not modality specific, as spatial processing was found to disrupt verbal maintenance. These results suggest a sequential and time-based function of working memory in which processing and storage rely on a single and general purpose attentional resource needed to run executive processes devoted to constructing, maintaining, and modifying ephemeral representations.