Search

Background: Even infants can recognize whether patterns of motion are or are not natural, yet an acknowledged challenge for science education is to promote adequate reasoning about such patterns. Since research indicates linkage between the conceptual bases of recognition and reasoning, it seems possible that recognition can be engaged to support reasoning.Purpose: Noting the theoretical and practical significance of showing that recognition can support reasoning, the reported research aimed to examine the possibility in relation to horizontal motion.Sample: The research was conducted with 167 children (mean age = 9.51 years) from Years 4, 5 and 6 of an English-medium school located in Lisbon, Portugal.Design and methods: Individual pre-tests were administered to all participants to assess initial reasoning about the direction and speed with which rolling balls travel after collision. Reasoning was assessed in the sense of both predicting and explaining. Thereafter, about two-thirds of the sample ...

The conceptual understanding that children display when predicting physical events has been shown to be inferior to the understanding they display when recognizing whether events proceed naturally. This has often been attributed to differences between the explicit engagement with conceptual knowledge required for prediction and the tacit engagement that suffices for recognition, and contrasting theories have been formulated to characterize the differences. Focusing on a theory that emphasizes omission at the explicit level of conceptual elements that are tacitly understood, the paper reports two studies that attempt clarification. The studies are concerned with 6- to 10-year-old children's understanding of, respectively, the direction (141 children) and speed (132 children) of motion in a horizontal direction. Using computer-presented billiards scenarios, the children predicted how balls would move (prediction task) and judged whether or not simulated motion was correct (recognition task). Results indicate that the conceptions underpinning prediction are sometimes interpretable as partial versions of the conceptions underpinning recognition, as the omission hypothesis would imply. However, there are also qualitative differences, which suggest partial dissociation between explicit and tacit understanding. It is suggested that a theoretical perspective that acknowledges this dissociation would provide the optimal framework for future research.

International audience; When students reason during school science, they often refer to conceptions that are derived from out-of-school experiences and are poor proxies for science orthodoxy. However, for some areas of science, these conceptions represent only a proportion of students' full conceptual knowledge, for tacit understanding exists that is superior to the understanding displayed when reasoning. Noting that tacit understanding is engaged when events are judged as natural or non-natural, the paper is concerned with software that: a) requires the direction and speed of falling objects to be predicted, i.e. a typical science reasoning task that engages conceptual knowledge; b) presents simulations of predicted motion in the expectation that its naturalness or non-naturalness would be recognised. An evaluation study is reported where children aged 8 to 12 years worked with the software in contexts that typify computer use in classrooms, i.e. individually under adult guidance (n = 44 children) or in pairs with a classmate (n = 48 children). They were observed while they did this. Reasoning about object fall was assessed via change from individual pre-tests administered prior to software usage to individual post-tests administered a few weeks afterwards. The children who worked with the software showed greater pre- to post-test gains in conceptual understanding than control children (n = 47 children), who lacked software experience. The gains were especially marked for the children who worked in pairs. The approach taken is contrasted with traditional approaches to conceptual change in school science, e.g. strategies that rely upon classroom experiments.

Adults make erroneous predictions about object fall despite recognizing when observed displays are correct or incorrect. Prediction requires explicit engagement with conceptual knowledge, whereas recognition can be achieved through tacit processing. Therefore, it has been suggested that the greater challenge imposed by explicit engagement leads to elements of conceptual understanding being omitted from prediction that are included in recognition. Acknowledging that research with children provides a significant context for exploring this "omission hypothesis" further, this article reports two studies with 6- to 10-year-olds, each of which used prediction and recognition tasks. Study 1 (N=137) focused on understanding of direction of fall, and Study 2 (N=133) addressed speed. Although performance on the recognition tasks was generally superior to performance on the prediction tasks, qualitative differences also emerged. These differences argue against interpreting explicit level understanding purely in terms of omission of tacit constructs, and the article outlines alternative models that may account for the data.

Depressed individuals show hypersensitivity to negative feedback during cognitive testing, which can precipitate subsequent errors and thereby impair a broad range of cognitive abilities. We studied the neural mechanisms underlying this feedback hypersensitivity using functional magnetic resonance imaging (fMRI) with a reversal learning task that required subjects to ignore misleading negative feedback on some trials. Thirteen depressed subjects with major depressive disorder (MDD), 12 depressed subjects with bipolar disorder (BD) and 15 healthy controls participated. The MDD group, but not the BD group, demonstrated enhanced sensitivity to negative feedback compared to controls, as indicated by the rates of rule reversal following misleading negative feedback. In the control and BD groups, hemodynamic activity was significantly higher in the dorsomedial and ventrolateral prefrontal cortices during reversal shifting, and significantly lower in the right amygdala in response to negative feedback. The extent to which the amygdala showed less activity during negative feedback correlated inversely with the behavioral tendency to reverse after misleading feedback. This effect was not present in the MDD group, who also failed to recruit the prefrontal cortex during behavioral reversal. Hypersensitivity to negative feedback is present in unmedicated depressed patients with MDD. Disrupted top-down control by the prefrontal cortex of the amygdala may underlie this abnormal response to negative feedback in unipolar depression.

Background Studies have demonstrated neuropsychological deficits across a variety of cognitive domains in depression. Few studies have directly compared depressed subjects with major depressive disorder (MDD) and bipolar disorder (BD), and many are confounded by medication status across subjects. In this study, we compared the performance of unmedicated currently depressed MDD and BD groups on a battery of neuropsychological tests that included measures of risk taking and reflection impulsivity. Methods Twenty-two MDD, seventeen BDII, and 25 healthy control subjects (HC), matched for age and IQ, were assessed on a battery of neuropsychological tests. Results The depressed groups showed comparable ratings of depression severity and age of illness onset. The MDD group was impaired on tests of spatial working memory and attentional shifting, sampled less information on a test of reflection impulsivity, and was oversensitive to loss trials on a decision-making test. The BDII subjects were generally intact and did not differ significantly from control subjects on any test. Conclusions These data indicate differing profiles of cognitive impairment in unmedicated depressed MDD versus BDII subjects. Moderately depressed BDII subjects displayed relatively intact cognitive function, whereas MDD subjects demonstrated a broader range of executive impairments. These cognitive deficits in depression were not attributable to current medication status.

Investigation of the impact of traumatic brain injury (TBI) on the functional brain network that mediates working memory function.Functional magnetic resonance imaging (fMRI) during an n-back working memory task in nine chronic-stage patients with TBI and nine age-matched healthy controls. In addition to classical analyses investigating regional activity, the authors examined functional connectivity of the brain regions critical to working memory performance using psychophysiological interaction (PPI) analyses.Patients with TBI made a greater percentage of errors than controls at high working memory load conditions. The fMRI data showed that the activation of the left inferior parietal gyrus (LIPG) was significantly reduced, whereas the activation of the right inferior frontal gyrus (RIFG) was significantly increased in patients compared with controls. Task performance accuracy was significantly associated with the activation of the LIPG in controls and the activation of the RIFG in patients. PPI analyses on fMRI data further suggested that the functional connectivity between the RIFG and LIPG was compromised in patients.The abnormal functional connectivity between LIPG and RIFG may underlie the observed working memory deficits and abnormal brain activation pattern in patients.

Objectives: Neuropsychological studies in subjects with bipolar disorder (BD) have reported deficits on a variety of cognitive measures. However, because the majority of subjects were medicated at the time of testing in previous studies, it is currently unclear whether the pattern of deficits reported is related to BD itself or to psychotropic medication. We addressed this issue by examining cognitive performance in a group of unmedicated, currently depressed subjects with BD. Methods: Forty-nine unmedicated subjects who met DSM-IV criteria for BD, depressed phase, and 55 control subjects participated in this study. Most patients were diagnosed with bipolar II disorder. Performance on emotion-dependent, or ‘hot’, and emotion-independent, or ‘cold’, cognitive tasks was assessed using tests from the Cambridge Neuropsychological Test Automated Battery. Results: The groups were well matched with respect to general intelligence and demographic variables. Deficits in the unmedicated depressed BD group were apparent on tests tapping ‘hot’ cognitive processing, for example the Cambridge Gamble task and the Probabilistic Reversal Learning task. However, other than a deficit on the Spatial Span test in the depressed BD subjects, the groups performed equivalently on most measures of ‘cold’ cognitive processing, for example visual memory, attention, and working memory. Conclusions: These data suggest that deficits on tests involving reward processing, short-term spatial memory storage, and sensitivity to negative feedback in depressed BD subjects represent an effect of the illness itself and not mood-stabilizing medication.