In light of the adult model of a hemispheric asymmetry of global and local processing, we compared children (Mage = 8.4 years) to adults in a global-local reaction time (RT) paradigm. Hierarchical designs (large shapes made of small shapes) were presented randomly to each visual field, and participants were instructed to identify either the global or the local level in each of two blocks. We obtained evidence of a global-local processing asymmetry, with stronger effects for children than for adults. In both children and adults, responses were faster and more accurate for global identification in the right hemisphere and for local identification in the left hemisphere. Similarly, a significant asymmetry of global and local interference was obtained in children but not in adults. Interference reflects the RT cost of conflicting information at the nonattended level. For example, local interference indicates the degree to which inconsistency at the local level slows global identification. Stronger evidence for lateralized processing in children is discussed within the framework of increasing interhemispheric transfer. That is, as interhemispheric transfer increases, cost of presentation to the nonpreferred hemisphere (e.g., local identification in the right hemisphere) is reduced. 相似文献
Limb apraxia is a neurological deficit characterized by an inability to pantomime and/or imitate gestures, which can result from neurodegenerative disorders such as Alzheimer's disease (AD). The major goal of the study was to describe comprehensively the apraxia deficits observed in AD patients and to relate those deficits to general cognitive status, measures of daily activity, and other neuropsychological measures. Limb apraxia was assessed on a variety of conceptual and gesture production tasks in 30 AD patients. As a group, AD patients were impaired across gesture production tasks: of note was the greater impairment in imitation, as opposed to pantomime, which was especially pronounced when patients were imitating with a delay. Imitation performance was best predicted by measures of visuospatial processing, while imitation with delay was best predicted by measures of working memory. In addition, pantomime in response to pictures of tools was less accurate than Pantomime to Verbal Command and holding the tool during performance did not decrease the participants' impairment, while introducing a verbal cue during imitation increased the severity of deficits. Furthermore, investigation into patterns of deficits clearly demonstrated that the nature of limb apraxia deficits observed in AD can be quite heterogeneous and that dissociations between the conceptual and the production system exist. Finally, we also report on significant correlations between general cognitive status and limb apraxia. 相似文献
In order to prevent tunnel vision, and ultimately miscarriages of justice, police, prosecutors, and judges must remain open to alternative scenarios in which the suspect is in fact innocent. However, it is not evident from the literature that people are sufficiently aware of how alternative scenarios should be employed in the decision‐making process. In the present research, participants read a case vignette and formed an impression of the suspect's guilt. Some participants were made familiar with an alternative scenario. Others were not only presented with an alternative scenario but were also instructed to score (with pen and paper) the extent to which every piece of evidence fitted in the primary and the alternative scenario. Findings suggest that this pen‐and‐paper task helped to reduce tunnel vision. 相似文献
In Alzheimer's disease (AD), it is now well established that recollection is impaired from the beginning of the disease, whereas findings are less clear concerning familiarity. One of the most important mechanisms underlying familiarity is the sense of familiarity driven by processing fluency. In this study, we attempted to attenuate recognition memory deficits in AD by maximizing the salience of fluency cues in two conditions of a recognition memory task. In one condition, targets and foils have been created from the same pool of letters (Overlap condition). In a second condition, targets and foils have been derived from two separate pools of letters (No‐Overlap condition), promoting the use of letter‐driven visual and phonetic fluency. Targets and foils were low‐frequency words. The memory tasks were performed by 15 patients with AD and 16 healthy controls. Both groups improved their memory performance in the No‐Overlap condition compared to the Overlap condition. Patients with AD were able to use fluency cues during recognition memory as older adults did, but this did not allow to compensate for dysfunction of recognition memory processes. 相似文献
Visual search is often slow and difficult for complex stimuli such as feature conjunctions. Search efficiency, however, can improve with training. Search for stimuli that can be identified by the spatial configuration of two elements (e.g., the relative position of two colored shapes) improves dramatically within a few hundred trials of practice. Several recent imaging studies have identified neural correlates of this learning, but it remains unclear what stimulus properties participants learn to use to search efficiently. Influential models, such as reverse hierarchy theory, propose two major possibilities: learning to use information contained in low-level image statistics (e.g., single features at particular retinotopic locations) or in high-level characteristics (e.g., feature conjunctions) of the task-relevant stimuli. In a series of experiments, we tested these two hypotheses, which make different predictions about the effect of various stimulus manipulations after training. We find relatively small effects of manipulating low-level properties of the stimuli (e.g., changing their retinotopic location) and some conjunctive properties (e.g., color-position), whereas the effects of manipulating other conjunctive properties (e.g., color-shape) are larger. Overall, the findings suggest conjunction learning involving such stimuli might be an emergent phenomenon that reflects multiple different learning processes, each of which capitalizes on different types of information contained in the stimuli. We also show that both targets and distractors are learned, and that reversing learned target and distractor identities impairs performance. This suggests that participants do not merely learn to discriminate target and distractor stimuli, they also learn stimulus identity mappings that contribute to performance improvements. 相似文献
How do people automatize their dual-task performance through bottleneck bypassing (i.e., accomplish parallel processing of the central stages of two tasks)? In the present work we addressed this question, evaluating the impact of sensory–motor modality compatibility—the similarity in modality between the stimulus and the consequences of the response. We hypothesized that incompatible sensory–motor modalities (e.g., visual–vocal) create conflicts within modality-specific working memory subsystems, and therefore predicted that tasks producing such conflicts would be performed less automatically after practice. To probe for automaticity, we used a transfer psychological refractory period (PRP) procedure: Participants were first trained on a visual task (Exp. 1) or an auditory task (Exp. 2) by itself, which was later presented as Task 2, along with an unpracticed Task 1. The Task 1–Task 2 sensory–motor modality pairings were either compatible (visual–manual and auditory–vocal) or incompatible (visual–vocal and auditory–manual). In both experiments we found converging indicators of bottleneck bypassing (small dual-task interference and a high rate of response reversals) for compatible sensory–motor modalities, but indicators of bottlenecking (large dual-task interference and few response reversals) for incompatible sensory–motor modalities. Relatedly, the proportion of individuals able to bypass the bottleneck was high for compatible modalities but very low for incompatible modalities. We propose that dual-task automatization is within reach when the tasks rely on codes that do not compete within a working memory subsystem.