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Selected AbstractsReorientation by geometric and landmark information in environments of different sizeDEVELOPMENTAL SCIENCE, Issue 5 2005Giorgio Vallortigara It has been found that disoriented children could use geometric information in combination with landmark information to reorient themselves in large but not in small experimental spaces. We tested domestic chicks in the same task and found that they were able to conjoin geometric and nongeometric (landmark) information to reorient themselves in both the large and the small space used. Moreover, chicks reoriented immediately when displaced from a large to a small experimental space and vice versa, suggesting that they used the relative metrics of the environment. However, when tested with a transformation (affine transformation) that alters the geometric relations between the target and the shape of the environment, chicks tended to make more errors based on geometric information when tested in the small than in the large space. These findings suggest that the reliance of the use of geometric information on the spatial scale of the environment is not restricted to the human species. [source] Error patterns in word reading among primary school children: A cross-orthographic studyDYSLEXIA, Issue 1 2004Louise Miller Guron Abstract A comparative investigation of word reading efficiency indicates that different strategies may be used by English and Swedish early readers. In a first study, 328 native English speakers from UK Years 3 and 6 completed a pen-and-paper word recognition task (the Wordchains test). Results were analysed for frequency and type of errors committed. A sample of 123 chronological-age-matched Swedish children carried out the same task on a matched Swedish test. For a sub-sample of 68 English/Swedish pairs matched on word recognition score and sex, significant differences were observed in a comparison of average and low scorers from the two language groups. The English children attempted more task items and committed more errors, while the Swedish group corrected their errors more, suggesting a difference in approach to the task. A second study of a larger Swedish sample (241 participants) found the same pattern of errors as Study 1. The implications of these findings are discussed in relation to the effects of orthographic depth and morphemic complexity. Copyright © 2004 John Wiley & Sons, Ltd. [source] Repetition suppression of induced gamma band responses is eliminated by task switchingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2006Thomas Gruber Abstract The formation of cortical object representations requires the activation of cell assemblies, correlated by induced oscillatory bursts of activity >,20 Hz (induced gamma band responses; iGBRs). One marker of the functional dynamics within such cell assemblies is the suppression of iGBRs elicited by repeated stimuli. This effect is commonly interpreted as a signature of ,sharpening' processes within cell-assemblies, which are behaviourally mirrored in repetition priming effects. The present study investigates whether the sharpening of primed objects is an automatic consequence of repeated stimulus processing, or whether it depends on task demands. Participants performed either a ,living/non-living' or a ,bigger/smaller than a shoebox' classification on repeated pictures of everyday objects. We contrasted repetition-related iGBR effects after the same task was used for initial and repeated presentations (no-switch condition) with repetitions after a task-switch occurred (switch condition). Furthermore, we complemented iGBR analysis by examining other brain responses known to be modulated by repetition-related memory processes (evoked gamma oscillations and event-related potentials; ERPs). The results obtained for the ,no-switch' condition replicated previous findings of repetition suppression of iGBRs at 200,300 ms after stimulus onset. Source modelling showed that this effect was distributed over widespread cortical areas. By contrast, after a task-switch no iGBR suppression was found. We concluded that iGBRs reflect the sharpening of a cell assembly only within the same task. After a task switch the complete object representation is reactivated. The ERP (220,380 ms) revealed suppression effects independent of task demands in bilateral posterior areas and might indicate correlates of repetition priming in perceptual structures. [source] Opposing effects of amygdala and orbital prefrontal cortex lesions on the extinction of instrumental responding in macaque monkeysEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2005Alicia Izquierdo Abstract Extinction is a well-known behavioural phenomenon that allows organisms to respond flexibly to a changing environment. Although recent work implicates the amygdala and orbital prefrontal cortex (PFo) in extinction of Pavlovian conditioned fear and aversion, much less is known about the neural bases of instrumental extinction. To explore the contribution of the macaque amygdala to flexible responding in the face of changing reward contingency, we tested the effects of selective, excitotoxic lesions of the amygdala on extinction of an instrumental response. For comparison, we evaluated the effects of ablation of PFo on the same task. Amygdala lesions facilitated the extinction of instrumental responses, whereas lesions of PFo had the opposite effect. [source] Impairment and recovery on a food foraging task following unilateral vestibular deafferentation in ratsHIPPOCAMPUS, Issue 4 2006Yiwen Zheng Abstract It has been suggested that the vestibular system may contribute to the development of higher cognitive function, especially spatial learning and memory that uses idiothetic cues (e.g., dead reckoning). However, few studies have been done using behavioral tasks that could potentially separate the animals' ability for dead reckoning from piloting. The food foraging task requires the animal to continuously monitor and integrate self-movement cues and generate an accurate return path. It has been shown that bilateral vestibular-lesioned rats were impaired on this task. The present study used the same task to further examine the contribution of vestibular information to spatial navigation by comparing unilateral and bilateral lesions and by testing the animals at different time points following the lesion. The results demonstrated that animals with unilateral vestibular deafferentation were impaired in performing the task in the dark at 3 months after the lesion, and this impairment disappeared at 6 months after the lesion. This supports the notion that vestibular information contributes to dead reckoning and suggests possible recovery of function over time after the lesion. Animals with bilateral vestibular deafferentation were not able to be tested on the foraging task because they exhibited behavior distinct from the unilateral-lesioned animals, with significant hesitation in leaving their home cage for as long as 6 months after the lesion. © 2005 Wiley-Liss, Inc. [source] An efficient gait recognition based on a selective neural network ensembleINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 4 2008Heesung Lee Abstract The neural network ensemble is a learning paradigm where a collection of neural networks is trained for the same task. Generally, the ensemble shows better generalization performance than a single neural network. In this article, a selective neural network ensemble is applied to gait recognition. The proposed method selects some neural network based on the minimization of generalization error. Since the selection rule is directly incorporated into the cost function, we can obtain adequate component networks to constitute an ensemble. Experiments are performed with the NLPR database to show the performance of the proposed algorithm. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 18, 237,241, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). [source] Tibio-femoral loading during human gait and stair climbingJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2004William R. Taylor Abstract Surgical intervention of the knee joint routinely endeavors to recreate a physiologically normal joint loading environment. The loading conditions resulting from osteotomies, fracture treatment, ligament replacements, and arthroplasties of the knee are considered to have an impact on the long term clinical outcome; however, knowledge regarding in vivo loading conditions is limited. Using a previously validated musculoskeletal lower limb model, we predicted the tibio-femoral joint contact forces that occur in the human knee during the common daily activities of walking and stair climbing. The average resultant peak force during walking was 3.1 times body weight (BW) across four total hip arthroplasty patients. Inter-individual variations proved larger than the variation of forces for each patient repeating the same task. Forces through the knee were considerably larger during stair climbing than during walking: the average resultant peak force during stair climbing was 5.4 BW although peaks of up to 6.2 BW were calculated for one particular patient. Average anteroposterior peak shear components of 0.6 BW were determined during walking and 1.3 BW during stair climbing. These results confirm both the joint contact forces reported in the literature and the importance of muscular activity in creating high forces across the joint. The magnitudes of these forces, specifically in shear, have implications for all forms of surgical intervention in the knee. The data demonstrate that high contact and shear forces are generated during weight bearing combined with knee flexion angles greater than approximately 15°. Clinically, the conditions that produce these larger contact forces should be avoided during post-operative rehabilitation. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Increased Activation of the ACC During a Spatial Working Memory Task in Alcohol-Dependence Versus Heavy Social DrinkingALCOHOLISM, Issue 5 2010Sabine Vollstädt-Klein Background:, Activation of the anterior cingulate cortex (ACC) in a spatial working memory task has been associated with risk factors for alcohol use disorders such as low alcohol effects and positive alcohol expectations in adolescents. To transfer these results into adults, we used the same task in adults. Methods:, During functional magnetic resonance imaging, 12 light social, 7 heavy social, and 11 non-abstinent-dependent alcohol drinkers performed a spatial working memory task and completed measures of automatic alcohol-related thoughts and behavior (Obsessive,Compulsive Drinking Scale,OCDS), alcohol use of the last 90 days, and general intelligence. Results:, Behavioral performance in the spatial working memory task was not significantly different in all 3 groups. Controlling for differences in general intelligence alcohol-dependent participants showed a higher task-related activation of the dorsal ACC (dACC) in comparison with light and heavy social drinkers. Measures of the OCDS were positively correlated with the activation in the left hippocampus and right thalamus in all participants. Conclusions:, Our results support the findings of increased dACC activation during a spatial working memory task as a risk factor for alcohol dependence. Increased task-related activation in the dACC was only observed in alcohol-dependent participants and not in heavy social drinkers with comparable alcohol consumption. Furthermore, the absence of behavioral performance differences between groups as well as an association between dACC activation and working memory performance indicates subtle working memory deficits. Low capacity of working memory has been linked to more automatic and less self-regulated behavior in studies on natural reward processing. Therefore, additional neural activation during performance of the non-alcohol-related working memory task in participants with higher OCDS values in the left hippocampus and the right thalamus may be a consequence of decreased neural capacity because of distracting alcohol-related thoughts. [source] Intermanual transfer of a new writing occupation in young adults without disabilityOCCUPATIONAL THERAPY INTERNATIONAL, Issue 1 2002Megan E. Andree Abstract It has been shown that acquisition of a skill by one hand is facilitated by previous learning of the same skill with the other hand. This is called intermanual transfer of learning, or cross-education. The investigators examined intermanual transfer of occupation of writing in a group of 10 right-handed subjects with no known motor disabilities. Subjects learned to perform a novel occupation of writing a foreign alphabet letter with either their right or left hand. Later, subjects reproduced the skill with the practised and unpractised contralateral hand. Pen movements and surface electromyography of the first dorsal interosseus muscle were recorded to assess the transfer of learning. Analysis revealed an almost full transfer of the learned motor task between hands in either left-to-right or right-to-left direction when movement time and movement size were compared. This indicates that transfer did not depend on hand dominance. These findings suggest that a task already learned by one hand can positively influence the learning of the same task by the other hand. The results have important implications for occupational therapy , namely, that activities comprising tasks previously learned by one hand would be more effective in facilitating improved performance by the other hand than activities comprising previously unlearned tasks in the case of retraining skills in patients with amputation or hemiplegia. Because the participants in this study were a small number of college students, research should be carried out with larger participant pools and participants with disabilities to consolidate the findings. Copyright © 2002 Whurr Publishers Ltd. [source] SYMMETRIES OF THE KINGDOM: SUGGESTIONS FROM GIRARD AND BONHOEFFER ON THINKING THE CHURCH,STATE RELATIONTHE HEYTHROP JOURNAL, Issue 4 2010KEVIN LENEHANArticle first published online: 12 MAR 2010 The work of René Girard invites us to re-imagine a ,religious,secular' interactivity within social space in a way released from the violent dualisms of the ,sacred/profane.' Earlier Dietrich Bonhoeffer considered the same task and suggested directions for a positive theology of church-state relations, even as the inherited forms of these institutions were collapsing about him. This paper explores the Girardian scenario for church and state becoming rivalrous ,doubles', whether it be secular utopic projects doubling religious narratives of redemption, or churches doubling the state as parallel yet purer societies , and suggests resources from Bonhoeffer by which a non-rivalrous church-state relationality - both mutually-constituting and mutually-limiting - may be configured. [source] Socially biased learning among adult cottontop tamarins (Saguinus oedipus)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2010Christopher Dillis Abstract We presented adult cottontop tamarins (Saguinus oedipus) with a novel foraging task that had been used previously to examine socially biased learning of juvenile observers [Humle & Snowdon, Animal Behaviour 75:267,277, 2008]. The task could be solved in one of two ways, and thus allowed for an analysis of behavioral matching between an observer and a skilled demonstrator (trained to use one of the two methods exclusively). Because the demonstrator was an adult in both this study and the juvenile study, the influence of the observer's age could be isolated and examined, as well as the behavior of demonstrators toward observers of different ages. Our main goals were to (1) compare adults and juveniles acquiring the same task to identify how the age of the observer affects socially biased learning and (2) examine the relationship between socially biased learning and behavioral matching in adults. Although adults spent less time observing the trained demonstrators than did juveniles, the adults were more proficient at solving the task. Furthermore, even though observers did not overtly match the behavior of the demonstrator, observation remained an important factor in the success of these individuals. The findings suggested that adult observers could extract information needed to solve a novel foraging task without explicitly matching the behavior of the demonstrator. Adult observers begged much less than juveniles and demonstrators did not respond to begging from adult. Skill acquisition and the process of socially biased learning are, therefore, age-dependent and are influenced by the behavioral interactions between observer and demonstrator. To what extent this holds true for other primates or animal species still needs to be more fully investigated and considered when designing experiments and interpreting results. Am. J. Primatol. 72:287,295, 2010. © 2009 Wiley-Liss, Inc. [source] Parenting and the development of conduct disorder and hyperactive symptoms in childhood: a prospective longitudinal study from 2 months to 8 yearsTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 4 2003Julian Morrell Background:, This study investigated the early processes involved in the development of symptoms of conduct disorder and hyperactivity. Method:, The study employed a prospective design, over a period from 2 months to 8 years. Detailed observational data of early and later mother,child interactions were collected, infant prefrontal function (the A not B task) was assessed, and symptoms of child conduct disorder and hyperactivity were rated by maternal report at age 5 and 8 years. Results:, The principal findings of the study were that emotional dysregulation on the A not B task at 9 months predicted symptoms of conduct disorder at 5 and 8 years, and delayed object reaching times on the same task predicted hyperactive symptoms at 5 years. These two developmental trajectories were associated with distinct patterns of early parenting that were strongly influenced by infant gender. Thus, in boys early emotional dysregulation was predicted by rejecting and coercive parenting, and delayed reaching on the A not B task by coercive parenting, whereas in girls only continuity from earlier infant behaviour could be demonstrated. There was strong continuity between these early infant behaviours and later child disturbance that was partially mediated by parenting for conduct disorder symptoms (maternal hostile parenting in boys, and maternal coercive parenting in girls), but not for hyperactive symptoms. Conclusions:, These data would suggest that only in boys was there evidence for the existence of a sensitive period for the development of hyperactive symptoms, and to a lesser extent, conduct disorder symptoms. [source] Phase-dependent and task-dependent modulation of stretch reflexes during rhythmical hand tasks in humansTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Ruiping Xia Phase-dependent and task-dependent modulation of reflexes has been extensively demonstrated in leg muscles during locomotory activity. In contrast, the modulation of reflex responses of hand muscles during rhythmic movement is poorly documented. The objective of this study was to determine whether comparable reflex modulation occurs in muscles controlling finger motions during rhythmic, fine-motor tasks akin to handwriting. Twelve healthy subjects performed two rhythmic tasks while reflexes were evoked by mechanical perturbations applied at various phases of each task. Electromyograms (EMGs) were recorded from four hand muscles, and reflexes were averaged during each task relative to the movement phase. Stretch reflexes in all four muscles were found to be modulated in amplitude with respect to the phase of the rhythmic tasks, and also to vary distinctly with the tasks being conducted. The extent and pattern of reflex modulation differed between muscles in the same task, and between tasks for the same muscle. Muscles with a primary role in each task showed a higher correlation between reflex response and background EMG than other muscles. The results suggest that the modulation patterns observed may reflect optimal strategies of central,peripheral interactions in controlling the performance of fine-motor tasks. As with comparable studies on locomotion, the phase-dependency of the stretch reflexes implies a dynamically fluctuating role of proprioceptive feedback in the control of the hand muscles. The clear task-dependency is also consistent with a dynamic interaction of sensory feedback and central programming, presumably adapted to facilitate the successful performance of the different fine-motor tasks. [source] Seeing the phantom: A functional magnetic resonance imaging study of a supernumerary phantom limb,ANNALS OF NEUROLOGY, Issue 6 2009Asaid Khateb PhD Objective Supernumerary phantom limb (SPL) is a rare neurological manifestation where patients with a severe stroke-induced sensorimotor deficit experience the illusory presence of an extra limb that duplicates a real one. The illusion is most often experienced as a somesthetic phantom, but rarer SPLs may be intentionally triggered or seen. Here, we report the case of a left visual, tactile, and intentional SPL caused by right subcortical damage in a nondeluded woman. Methods Using functional magnetic resonance imaging, we investigated the multimodal nature of this phantom, which the patient claimed to be able see, use, and move intentionally. The patient participated in a series of sensorimotor and motor imagery tasks involving the right, the left plegic, and the SPL's hand. Results Right premotor and motor regions were engaged when she imagined that she was scratching her left cheek with her left plegic hand, whereas when she performed the same task with the SPL, additional left middle occipital areas were recruited. Moreover, comparison of responses induced by left cheek (subjectively feasible) versus right cheek scratching (reportedly unfeasible movement) with the SPL demonstrated significant activation in right somesthetic areas. Interpretation These findings demonstrate that intentional movements of a seen and felt SPL activate premotor and motor areas together with visual and sensory cortex, confirming its multimodal dimension and the reliability of the patient's verbal reports. This observation, interpreted for cortical deafferentation/disconnection caused by subcortical brain damage, constitutes a new but theoretically predictable entity among disorders of bodily awareness. Ann Neurol 2009;65:698,705 [source] The effects of interleaved practiceAPPLIED COGNITIVE PSYCHOLOGY, Issue 6 2010Kelli Taylor Previous research shows that interleaving rather than blocking practice of different skills (e.g. abcbcacab instead of aaabbbccc) usually improves subsequent test performance. Yet interleaving, but not blocking, ensures that practice of any particular skill is distributed, or spaced, because any two opportunities to practice the same task are not consecutive. Hence, because spaced practice typically improves test performance, the previously observed test benefits of interleaving may be due to spacing rather than interleaving per se. In the experiment reported herein, children practiced four kinds of mathematics problems in an order that was interleaved or blocked, and the degree of spacing was fixed. The interleaving of practice impaired practice session performance yet doubled scores on a test given one day later. An analysis of the errors suggested that interleaving boosted test scores by improving participants' ability to pair each problem with the appropriate procedure. Copyright © 2009 John Wiley & Sons, Ltd. [source] Increased realism in eyewitness confidence judgements: the effect of dyadic collaborationAPPLIED COGNITIVE PSYCHOLOGY, Issue 5 2003Carl Martin Allwood This study investigated to what extent, and under what circumstances, pair collaboration influences the realism in eyewitness confidence in event memory. The participants first saw a short film clip and then confidence rated their answers to questions on its content. A condition (the Individual,Pair condition) where individual effort preceded pair collaboration showed better calibration compared with a condition (the Simple Pair condition) where no individual effort took place. Furthermore, within the Individual,Pair condition, better calibration, and lower overconfidence, were found in the pair phase compared with the individual phase. The eyewitnesses in the Individual,Pair condition made more realistic judgements of the total number of questions answered correctly. In a control experiment no effect on realism in confidence was found when individuals performed the same task twice. The improved realism in the Individual,Pair condition may partly be explained in terms of the increased accuracy and lowered confidence found for such items where the pair members' had given different answers in the individual phase, and by a risky shift effect for such items where they had given the same answer. Copyright © 2003 John Wiley & Sons, Ltd. [source] Willingness to communicate: can online chat help?1INTERNATIONAL JOURNAL OF APPLIED LINGUISTICS, Issue 2 2006Mark Freiermuth This study compared the experiences of small groups of female Japanese university students communicating in English to solve tasks using online chat with those who solved the same tasks in face-to-face settings using spoken language. The groups were compared using a counterbalanced research design so that the nine groups consisting of four participants each took part in solving tasks in both the online mode and the traditional face-to-face setting. Data gathered from questionnaires, along with an analysis of the discourse produced by students, led to the conclusion that under the conditions in the study, online chatting provided a more comfortable environment, enhancing students' willingness to communicate. Regarding benefits to the language teacher, online chat provides another fruitful tool to enhance interaction in the target language. [source] An empirical study of the influence of departmentalization and organizational position on software maintenanceJOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 1 2002Dowming Yeh Abstract Differences between software development and maintenance imply that software maintenance work should be measured and managed somewhat differently from software development. On the other hand, maintenance programmers frequently perform the same tasks as development programmers do. How to departmentalize maintenance and development is thus becoming an issue. Departmentalization in software development and maintenance can be classified into two categories, maintenance separated from development and maintenance jointly with development. Departmentalization has its strengths and weaknesses. In this work, quantitative empirical methods are applied to investigate the influence of departmentalization on fulfillment opportunity, time allocations of activities, problem occurrences, and management process in software maintenance. Seven hypotheses are formed and tested by statistical methods. The result shows that separate organizations demonstrate specialization in software maintenance, but managerial attitudes also aggravate the potential status difference for such organizations. Other major pitfalls for departmentalization are also identified. Copyright © 2002 John Wiley & Sons, Ltd. [source] The sensitivity of human event-related potentials and reaction time to mobile phone emitted electromagnetic fieldsBIOELECTROMAGNETICS, Issue 4 2006D.L. Hamblin Abstract There is some evidence to suggest that exposure to mobile phones (MPs) can affect neural activity, particularly in response to auditory stimuli. The current investigation (n,=,120) aimed to test recent findings in this area, namely that N100 amplitude and latency would decrease, and that P300 latency and reaction time (RT) would increase under active relative to sham exposure during an auditory task. Visual measures were also explored. A double blind, counterbalanced, crossover design was employed where subjects attended two sessions 1 week apart. In both sessions participants (1) performed auditory and visual oddball tasks while electroencephalogram (EEG) was recorded with a MP set to sham exposure mounted over the temporal region, and (2) performed the same tasks while the handset was set to active/sham. When active, the MP transmitted for 30 min at 895 MHz (average power 250 mW, pulse modulated at 217 Hz, average SAR 0.11 W/kg). Paired t -tests compared difference scores from the sham/sham session to those from the sham/active condition. The study was designed to detect differences of of a standard deviation with a power of 0.80. There was no significant difference between exposure conditions for any auditory or visual event related potential (ERP) component or RT. As previous positive findings were not replicated, it was concluded that there is currently no evidence that acute MP exposure affects these indices of brain activity. Bioelectromagnetics 27:265,273, 2006. © 2006 Wiley-Liss, Inc. [source] | |||||||||||||||||||