954 resultados para Performance cognitive


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This study examined the extent to which students could fake responses on personality and approaches to studying questionnaires, and the effects of such responding on the validity of non-cognitive measures for predicting academic performance (AP). University students produced a profile of an ‘ideal’ student using the Big-Five personality taxonomy, which yielded a stereotype with low scores for Neuroticism, and high scores for the other four traits. A sub-set of participants were allocated to a condition in which they were instructed to fake their responses as University applicants, portraying themselves as positively as possible. Scores for these participants revealed higher scores than those in a control condition on measures of deep and strategic approaches to studying, but lower scores on the surface approach variable. Conscientiousness was a significant predictor of AP in both groups, but the predictive effect of approaches to studying variables and Openness to Experience identified in the control group was lower in the group who faked their responses. Non-cognitive psychometric measures can be valid predictors of AP, but scores on these measures can be affected by instructional set. Further implications for psychometric measurement in educational settings are discussed.

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A survey is made of the literature relating to a number of dimensions of cognitive style, from which it is concluded that cognitive style has a strong theoretical potential as a predictor of academic performance. It is also noted that there have been few attempts to relate co gnitive style to academic performance, and that these have met with limited success. On the assumption that theories of individual differences should be congruent with theories of general functioning, an examination is made of the model of cognition presupposed by ,dimen sions of cognitive style. A central feature of this model is the distinction between cognitive content and cognitive structure. The origins of this distinction are traced back to the normative and experimental or quasi-experimental characteristics of research in psychology. The validity of the distinction is examined with reference to modern research findings, and the conclusion is drawn that the norma~ive experimental method is an increasingly inappropriate tool of research when applied to higher levels of cognitive functioning, as it cannot handle subject idiosyncracy or patterns of interaction. An examination of the presuppositions of educational research leads to the complementary conclusion that the research methods imply an oversimplified model of the educational situation. Two empirical studies are reported: (1) An experiment using conventional cognitive style dimensions as predictors of performance under two teaching methods (2) An attempt to predict individual differences in overall academic performance by means of a research technique which uses a questionnaire, intra-individual scoring, and an analysis of patterns of responses, and which attempts to take some account of subject idiosyncracy. The implifications of these studies for fUrther research are noted.

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Compulsive checking is known to influence memory, yet there is little consideration of checking as a cognitive style within the typical population. We employed a working memory task where letters had to be remembered in their locations. The key experimental manipulation was to induce repeated checking after encoding by asking about a stimulus that had not been presented. We recorded the effect that such misleading probes had on a subsequent memory test. Participants drawn from the typical population but who scored highly on a checking-scale had poorer memory and less confidence than low scoring individuals. While thoroughness is regarded as a quality, our results indicate that a cognitive style that favours repeated checking does not always lead to the best performance as it can undermine the authenticity of memory traces. This may affect various aspects of everyday life including the work environment and we discuss its implications and possible counter-measures. Copyright © 2010 John Wiley & Sons, Ltd.

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IEEE 802.11 standard is the dominant technology for wireless local area networks (WLANs). In the last two decades, the Distributed coordination function (DCF) of IEEE 802.11 standard has become the one of the most important media access control (MAC) protocols for mobile ad hoc networks (MANETs). The DCF protocol can also be combined with cognitive radio, thus the IEEE 802.11 cognitive radio ad hoc networks (CRAHNs) come into being. There were several literatures which focus on the modeling of IEEE 802.11 CRAHNs, however, there is still no thorough and scalable analytical models for IEEE 802.11 CRAHNs whose cognitive node (i.e., secondary user, SU) has spectrum sensing and possible channel silence process before the MAC contention process. This paper develops a unified analytical model for IEEE 802.11 CRAHNs for comprehensive MAC layer queuing analysis. In the proposed model, the SUs are modeled by a hyper generalized 2D Markov chain model with an M/G/1/K model while the primary users (PUs) are modeled by a generalized 2D Markov chain and an M/G/1/K model. The performance evaluation results show that the quality-of-service (QoS) of both the PUs and SUs can be statistically guaranteed with the suitable settings of duration of channel sensing and silence phase in the case of under loading.

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The Unified Modeling Language (UML) has quickly become the industry standard for object-oriented software development. It is being widely used in organizations and institutions around the world. However, UML is often found to be too complex for novice systems analysts. Although prior research has identified difficulties novice analysts encounter in learning UML, no viable solution has been proposed to address these difficulties. Sequence-diagram modeling, in particular, has largely been overlooked. The sequence diagram models the behavioral aspects of an object-oriented software system in terms of interactions among its building blocks, i.e. objects and classes. It is one of the most commonly-used UML diagrams in practice. However, there has been little research on sequence-diagram modeling. The current literature scarcely provides effective guidelines for developing a sequence diagram. Such guidelines will be greatly beneficial to novice analysts who, unlike experienced systems analysts, do not possess relevant prior experience to easily learn how to develop a sequence diagram. There is the need for an effective sequence-diagram modeling technique for novices. This dissertation reports a research study that identified novice difficulties in modeling a sequence diagram and proposed a technique called CHOP (CHunking, Ordering, Patterning), which was designed to reduce the cognitive load by addressing the cognitive complexity of sequence-diagram modeling. The CHOP technique was evaluated in a controlled experiment against a technique recommended in a well-known textbook, which was found to be representative of approaches provided in many textbooks as well as practitioner literatures. The results indicated that novice analysts were able to perform better using the CHOP technique. This outcome seems have been enabled by pattern-based heuristics provided by the technique. Meanwhile, novice analysts rated the CHOP technique more useful although not significantly easier to use than the control technique. The study established that the CHOP technique is an effective sequence-diagram modeling technique for novice analysts.

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The purpose of this study was to examine the effects of acute active dehydration by exercise in a hot, humid environment on cognitive performance. Our findings were inconclusive compared to previous studies that reported decreased cognitive performance in manual laborers and military personnel working in extreme environmental conditions.

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Objective: To evaluate the impact of alcohol use, which is widespread in human immunodeficiency virus (HIV)+ individuals, on highly active antiretroviral therapy (HAART)-associated immune and cognitive improvements and the relationship between those two responses. Methods: In a case-control longitudinal study, thymic volume, cognition, and immune responses were evaluated at baseline and after 6 months therapy in HIV+ and HIV- controls. Cognitive performance was evaluated using the HIV Dementia Score (HDS) and the California Verbal Learning Test (CVLT). Results: Prior to HAART, thymic volume varied considerably from 2.7 to 29.3 cm3 (11 ± 7.2 cm3). Thymic volume at baseline showed a significantly inverse correlation with the patient’s number of years of drinking (r2 = 0.207; p < 0.01), as well as HDS and the CVLT scores in both HIV-infected (r2 = 0.37, p = 0.03) and noninfected (r2 = 0.8, p = 0.01). HIV-infected individuals with a small thymic volume scored in the demented range, as compared with those with a larger thymus (7 ± 2.7 vs. 12 ± 2.3, p = 0.005). After HAART, light/moderate drinkers exhibited thymus size twice that of heavy drinkers (14.8 ± 10.4 vs. 6.9 ± 3.3 cm3). Conclusions: HAART-associated increases of thymus volume appear to be negatively affected by alcohol consumption and significantly related to their cognitive status. This result could have important clinical implications.

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For years, researchers and human resources specialists have been searching for predictors of performance as well as for relevant performance dimensions (Barrick & Mount, 1991; Borman & Motowidlo, 1993; Campbell, 1990; Viswesvaran et al., 1996). In 1993, Borman and Motowidlo provided a framework by which traditional predictors such as cognitive ability and the Big Five personality factors predicted two different facets of performance: 1) task performance and 2) contextual performance. A meta-analysis was conducted to assess the validity of this model as well as that of other modified models. The relationships between predictors such as cognitive ability and personality variables and the two outcome variables were assessed. It was determined that even though the two facets of performance may be conceptually different, empirically they overlapped substantially (p= .75). Finally, results show that there is some evidence for cognitive ability as a predictor of both task and contextual performance and conscientiousness as a predictor of both task and contextual performance. The possible mediation of predictor-- criterion relationships was also assessed. The relationship between cognitive ability and contextual performance vanished when task performance was controlled.

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The Unified Modeling Language (UML) has quickly become the industry standard for object-oriented software development. It is being widely used in organizations and institutions around the world. However, UML is often found to be too complex for novice systems analysts. Although prior research has identified difficulties novice analysts encounter in learning UML, no viable solution has been proposed to address these difficulties. Sequence-diagram modeling, in particular, has largely been overlooked. The sequence diagram models the behavioral aspects of an object-oriented software system in terms of interactions among its building blocks, i.e. objects and classes. It is one of the most commonly-used UML diagrams in practice. However, there has been little research on sequence-diagram modeling. The current literature scarcely provides effective guidelines for developing a sequence diagram. Such guidelines will be greatly beneficial to novice analysts who, unlike experienced systems analysts, do not possess relevant prior experience to easily learn how to develop a sequence diagram. There is the need for an effective sequence-diagram modeling technique for novices. This dissertation reports a research study that identified novice difficulties in modeling a sequence diagram and proposed a technique called CHOP (CHunking, Ordering, Patterning), which was designed to reduce the cognitive load by addressing the cognitive complexity of sequence-diagram modeling. The CHOP technique was evaluated in a controlled experiment against a technique recommended in a well-known textbook, which was found to be representative of approaches provided in many textbooks as well as practitioner literatures. The results indicated that novice analysts were able to perform better using the CHOP technique. This outcome seems have been enabled by pattern-based heuristics provided by the technique. Meanwhile, novice analysts rated the CHOP technique more useful although not significantly easier to use than the control technique. The study established that the CHOP technique is an effective sequence-diagram modeling technique for novice analysts.

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Recent studies indicate that a single bout of physical exercise can have immediatepositive effects on cognitive performance of children and adolescents. However, thetype of exercise that affects cognitive performance the most in young adolescents isnot fully understood. Therefore, this controlled study examined the acute effects ofthree types of 12-min classroom-based exercise sessions on information processingspeed and selective attention. The three conditions consisted of aerobic, coordination,and strength exercises, respectively. In particular, this study focused on the feasibilityand efficiency of introducing short bouts of exercise in the classroom. One hundredand ninety five students (5th and 6th grade; 10–13 years old) participated in a doublebaseline within-subjects design, with students acting as their own control. Exercise typewas randomly assigned to each class and acted as between-subject factor. Before andimmediately after both the control and the exercise session, students performed twocognitive tests that measured information processing speed (Letter Digit SubstitutionTest) and selective attention (d2 Test of Attention). The results revealed that exercisingat low to moderate intensity does not have an effect on the cognitive parameters testedin young adolescents. Furthermore, there were no differential effects of exercise type.The results of this study are discussed in terms of the caution which should be takenwhen conducting exercise sessions in a classroom setting aimed at improving cognitive performance.

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This study considers a dual-hop cognitive inter-vehicular relay-assisted communication system where all
communication links are non-line of sight ones and their fading is modelled by the double Rayleigh fading distribution.
Road-side relays (or access points) implementing the decode-and-forward relaying protocol are employed and one of
them is selected according to a predetermined policy to enable communication between vehicles. The performance of
the considered cognitive cooperative system is investigated for Kth best partial and full relay selection (RS) as well as
for two distinct fading scenarios. In the first scenario, all channels are double Rayleigh distributed. In the second
scenario, only the secondary source to relay and relay to destination channels are considered to be subject to double
Rayleigh fading whereas, channels between the secondary transmitters and the primary user are modelled by the
Rayleigh distribution. Exact and approximate expressions for the outage probability performance for all considered RS
policies and fading scenarios are presented. In addition to the analytical results, complementary computer simulated
performance evaluation results have been obtained by means of Monte Carlo simulations. The perfect match between
these two sets of results has verified the accuracy of the proposed mathematical analysis.