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201.
The integration of continuous and discrete latent variable models: potential problems and promising opportunities 总被引:3,自引:0,他引:3
Structural equation mixture modeling (SEMM) integrates continuous and discrete latent variable models. Drawing on prior research on the relationships between continuous and discrete latent variable models, the authors identify 3 conditions that may lead to the estimation of spurious latent classes in SEMM: misspecification of the structural model, nonnormal continuous measures, and nonlinear relationships among observed and/or latent variables. When the objective of a SEMM analysis is the identification of latent classes, these conditions should be considered as alternative hypotheses and results should be interpreted cautiously. However, armed with greater knowledge about the estimation of SEMMs in practice, researchers can exploit the flexibility of the model to gain a fuller understanding of the phenomenon under study. 相似文献
202.
Substantial evidence suggests that alterations in noradrenergic function contribute to the cognitive impairments of schizophrenia. Activation of post-junctional alpha 2a-adrenergic receptors in the prefrontal cortex by the alpha 2a-selective agonist guanfacine has demonstrated some preliminary benefit in subjects with schizophrenia treated with atypical antipsychotics. alpha 1-adrenergic receptor activity may be less important in mediating the cognitive impairments of schizophrenia. beta-adrenergic receptors may serve as another potential target for cognitive remediation in schizophrenia. However, the potential increase in memory consolidation in schizophrenia patients produced by beta-adrenergic agonists may be outweighed by the impairment in cognitive flexibility and executive functioning produced by beta-adrenergic agonists. Finally, norepinephrine reuptake inhibitors, such as atomoxetine, hold promise as potential cognitive enhancers in schizophrenia because of their ability to indirectly but selectively increase extracellular dopamine concentrations in the prefrontal cortex. 相似文献
203.
204.
Change blindness, the failure to detect visual changes that occur during a disruption, has increasingly been used to infer the nature of internal representations. If every change were detected, detailed representations of the world would have to be stored and accessible. However, because many changes are not detected, visual representations might not be complete, and access to them might be limited. Using change detection to infer the completeness of visual representations requires an understanding of the reasons for change blindness. This article provides empirical support for one such reason: change blindness resulting from the failure to compare retained representations of both the pre- and postchange information. Even when unaware of changes, observers still retained information about both the pre- and postchange objects on the same trial. 相似文献
205.
Psychological well-being has been generally associated with vigorous aerobic activity and structured aerobic activity in adolescents and children. Low-income children are at greater risk than the general population for experiencing high environmental stress and increased mental health problems. This study investigated the effects of a structured physical fitness program on psychological well-being in low-income Hispanic children. A total of 66, 33 girls, 33 boys, in Grade 4 were randomly assigned to either an Aerobic intensity (n = 34) or a Control intensity physical activity program (n = 32) for 6 wk. Psychological well-being was defined as scores on trait anxiety, depression, and self-esteem, measured, respectively, by the Trait Anxiety Inventory, Beck Depression Inventory, and Rosenberg Self-esteem scale. Analysis showed the children in the Aerobic intensity program significantly (p < .05) improved their cardiovascular fitness as measured by the PWC170 test. After the program was over, the children in this Aerobic group reported significantly (p < .05) less depression. The main effect for self-esteem reflected the Aerobic group's greater self-reported self-esteem. No differences were found on trait anxiety. The effects on depression and self-esteem may only be attributed to the cardiovascular improvement given the higher intensity physical activity program because causation was not assessed here. 相似文献
206.
Age differences in rereading 总被引:1,自引:0,他引:1
Younger and older adults read a series of expository and narrative passages twice in order to answer comprehension questions. Reading time was used to index attentional allocation to word, textbase, and situation model processing and to assess shifts in the allocation policy from the first to the second reading. Older readers' comprehension was at least as good as that of younger readers. Analysis of reading times suggested that for both genres, older adults allocated more attention to situation model features than younger adults did on the first reading, whereas young and old allocated attention similarly to this level of representation on the second reading, suggesting that mature readers may give greater priority to situation model construction when first encountering text. Also, for both genres, older adults showed relatively less facilitation than the young in word-level processing in rereading, suggesting that representation at this level is not as firmly established during reading or decays more quickly for older readers. For narrative texts only, this pattern also obtained for textbase processing. Collectively, these data show that age equivalence in text comprehension at the molar level may be accomplished through different processing routes at the molecular level. 相似文献
207.
In four experiments involving 184 participants, people rated their confidence that particular events had happened in their childhood (e.g., "Broke a window playing ball"). If participants had to unscramble a key word in a phrase just before rating it (e.g., "Broke a nwidwo [window] playing ball"), confidence ratings increased-the revelation effect. However, the pattern of revelation effects depended on the particular way in which participants processed key words (e.g., visualizing vs. counting vowels in the word window) approximately 10 min prior to rating life events that contained those words. Prior exposure to key words never in itself directly affected confidence ratings. These results demonstrate that one can manipulate the revelation effect by altering the processing that participants perform on words prior to unscrambling them. These results also pose difficulties for many accounts of the revelation effect. The major puzzle posed by our present findings is that unscrambling key words increases confidence that an event has happened in childhood, whereas prior exposure to these words does not. 相似文献
208.
A difficulty in the development and testing of psychological models is that they are typically evaluated solely on their ability to fit experimental data, with little consideration given to their ability to fit other possible data patterns. By examining how well model A fits data generated by model B, and vice versa (a technique that we call landscaping), much safer inferences can be made about the meaning of a model's fit to data. We demonstrate the landscaping technique using four models of retention and 77 historical data sets, and show how the method can be used to: (1) evaluate the distinguishability of models, (2) evaluate the informativeness of data in distinguishing between models, and (3) suggest new ways to distinguish between models. The generality of the method is demonstrated in two other research areas (information integration and categorization), and its relationship to the important notion of model complexity is discussed. 相似文献
209.
An integrated theory of the mind 总被引:23,自引:0,他引:23
Anderson JR Bothell D Byrne MD Douglass S Lebiere C Qin Y 《Psychological review》2004,111(4):1036-1060
Adaptive control of thought-rational (ACT-R; J. R. Anderson & C. Lebiere, 1998) has evolved into a theory that consists of multiple modules but also explains how these modules are integrated to produce coherent cognition. The perceptual-motor modules, the goal module, and the declarative memory module are presented as examples of specialized systems in ACT-R. These modules are associated with distinct cortical regions. These modules place chunks in buffers where they can be detected by a production system that responds to patterns of information in the buffers. At any point in time, a single production rule is selected to respond to the current pattern. Subsymbolic processes serve to guide the selection of rules to fire as well as the internal operations of some modules. Much of learning involves tuning of these subsymbolic processes. A number of simple and complex empirical examples are described to illustrate how these modules function singly and in concert. 相似文献
210.
Participants watched themselves in a mirror while another person behind them, hidden from view, extended hands forward on each side where participants' hands would normally appear. The hands performed a series of movements. When participants could hear instructions previewing each movement, they reported an enhanced feeling of controlling the hands. Hearing instructions for the movements also enhanced skin conductance responses when a rubber band was snapped on the other's wrist after the movements. Such vicarious agency was not felt when the instructions followed the movements, and participants' own covet movement mimicry was not essential to the influence of previews on reported control. 相似文献