90,747 research outputs found
DHA-rich oil modulates the cerebral haemodynamic response to cognitive tasks in healthy young adults: a near IR spectroscopy pilot study
The impact of dietary n-3 PUFA on behavioural outcomes has been widely researched; however, very little attention has been given to their impact on brain functioning in physiological terms. A total of twenty-two healthy adults took part in this double-blind, placebo-controlled study, wherein the cerebral haemodynamic effects of 12 weeks of daily dietary supplementation with either 1Â g DHA-rich or 1Â g EPA-rich fish oil (FO) or placebo (1Â g olive oil) were assessed. Relative changes in the concentration of oxygenated Hb (oxy-Hb) and deoxygenated Hb were assessed in the prefrontal cortex using near IR spectroscopy (NIRS) during the performance of four computerised cognitive tasks. Supplementation with DHA-rich FO, in comparison with placebo, resulted in a significant increase in the concentrations of oxy-Hb and total levels of Hb, indicative of increased cerebral blood flow (CBF), during the cognitive tasks. In comparison, no effect on CBF was observed following supplementation with EPA-rich FO, where concentration changes in the chromophores followed the same pattern as placebo. These encouraging pilot data warrant further application of NIRS in this area
Multi-task learning and transfer: The effect of algorithm representation
Exploring multiple classes of learning algorithms for those algorithms which perform best in multiple tasks is a complex problem of multiple-criteria optimisation. We use a genetic algorithm to locate sets of models which are not outperformed on all of the tasks. The genetic algorithm develops a population of multiple types of learning algorithms, with competition between individuals of different types. We find that inherent differences in the convergence time and performance levels of the different algorithms leads to misleading population effects. We explore the role that the algorithm representation and initial population has on task performance. Our findings suggest that separating the representation of different algorithms is beneficial in enhancing performance. Also, initial seeding is required to avoid premature convergence to non-optimal classes of algorithms
The on-going search for perspective-taking IRAPs : exploring the potential of the natural language-IRAP
Under a Relational Frame Theory (RFT) framework, researchers have investigated the role of deictic relational responding (perspective-taking) in the analysis of self in relation to others, place, and time. The aim of the current research was to develop IRAPs that targeted deictic relational responding with regard to the mental states of self and others. This was pursued in a series of experiments that employed a novel version of the IRAP, known as the Natural Language-IRAP (NL-IRAP). The use of the NL-IRAP allowed for the presentation of relatively complex statements that required participants to infer the thoughts or beliefs of others on a trial-by-trial basis within the IRAP. Across a sequence of six experiments, a self-focused IRAP required participants to respond to both positive and negative statements about themselves, whereas an other-focused IRAP required participants to respond to similar statements about others. Experiments 1 and 2 investigated perspective-taking with regard to an unspecified other. Experiments 3-6 investigated perspective-taking with regard to a specified other, with the specified relationship between self and other manipulated across experiments. The results of Experiments 1 and 2 indicated that the other-focused IRAP produced overall bias scores that were significantly stronger than responding to the self-focused IRAP. It is interesting that nonsignificant differences were recorded across Experiments 3-6 when other was specified. The findings obtained across the six studies highlight potentially important limitations in the use of the NL-IRAP as a measure of perspective-taking
The role of working memory and contextual constraints in children's processing of relative clauses
An auditory sentence comprehension task investigated the extent to which the integration of contextual and structural cues was mediated by verbal memory span with 32 English-speaking 6- to 8-year old children. Spoken relative clause sentences were accompanied by visual context pictures which fully (depicting the actions described within the relative clause) or partially (depicting several referents) met the pragmatic assumptions of relativisation. Comprehension of the main and relative clauses of centre-embedded and right-branching structures was compared for each context. Pragmatically-appropriate contexts exerted a positive effect on relative clause comprehension, but children with higher memory spans demonstrated a further benefit for main clauses. Comprehension for centre-embedded main clauses was found to be very poor, independently of either context or memory span. The results suggest that children have access to adult-like linguistic processing mechanisms, and that sensitivity to extra-linguistic cues is evident in young children and develops as cognitive capacity increases
Retrieval from memory: Vulnerable or inviolable?
We show that retrieval from semantic memory is vulnerable even to the mere presence of speech. Irrelevant speech impairs semantic fluencyânamely, lexical retrieval cued by a semantic category nameâbut only if it is meaningful (forward speech compared to reversed speech or words compared to nonwords). Moreover, speech related semantically to the retrieval category is more disruptive than unrelated speech. That phonemic fluencyâin which participants are cued with the first letter of words they are to reportâwas not disrupted by the mere presence of meaningful speech, only by speech in a related phonemic category, suggests that distraction is not mediated by executive processing load. The pattern of sensitivity to different properties of sound as a function of the type of retrieval cue is in line with an interference-by-process approach to auditory distraction
Further evidence on the effect of symbolic distance on Stroop-like interference
Pavese and UmiltĂ found that, in an enumeration task, Stroop-like interference is larger when the digit identity is symbolically close to the enumeration response than when it is symbolically far. In two experiments testing 49 undergraduates, we further explored this phenomenon using Francolini and Egeth's paradigm. We found that symbolic distance affected interference even when the stimulus was briefly presented and masked. In Exp. 2, which tested numerosities outside the subitizing range, individuals used a different enumeration strategy but showed the same symbolic distance effect. These results support the hypothesis that Stroop interference found in enumeration tasks depends on a rapid and automatic activation of digits' magnitude representation
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