Parallel distributed processing and neuropsychology: A neural network model of Wisconsin card sorting and verbal fluency

Neural networks can be used as a tool in the explanation of neuropsychological data. Using the Hebbian Learning Rule and other such principles as competition and modifiable interlevel feedback, researchers have successfully modeled a widely used neuropsychological test, the Wisconsin Card Sorting Test. One of these models is reviewed here and extended to a qualitative analysis of how verbal fluency might be modeled, which demonstrates the importance of accounting for the attentional components of both tests. Difficulties remain in programming sequential cognitive processes within a parallel distributed processing (PDP) framework and integrating exceedingly complex neuropsychological tests such as Proverbs. PDP neural network methodology offers neuropsychologists co-validation procedures within narrowly defined areas of reliability and validity.     

A causal model theory of the meaning of cause, enable, and prevent

The verbs cause , enable , and prevent express beliefs about the way the world works. We offer a theory of their meaning in terms of the structure of those beliefs expressed using qualitative properties of causal models, a graphical framework for representing causal structure. We propose that these verbs refer to a causal model relevant to a discourse and that "A causes B" expresses the belief that the causal model includes a link from A to B. "A enables/allows B" entails that the model includes a link from A to B, that A represents a category of events necessary for B, and that an alternative cause of B exists. "A prevents B" entails that the model includes a link from A to B and that A reduces the likelihood of B. This theory is able to account for the results of four experiments as well as a variety of existing data on human reasoning.     

Acute caffeine consumption enhances the executive control of visual attention in habitual consumers

Recent work suggests that a dose of 200–400 mg caffeine can enhance both vigilance and the executive control of visual attention in individuals with low caffeine consumption profiles. The present study seeks to determine whether individuals with relatively high caffeine consumption profiles would show similar advantages. To this end, we examined the effects of four caffeine doses (0 mg, 100 mg, 200 mg, 400 mg) on low- and high-level visual attention in individuals with high consumption profiles (n = 36), in a double-blind study using a repeated measures design. Results from the Attention Network Test indicated that caffeine enhanced both vigilance and the executive control of visual attention, but only at the highest administered dose (400 mg). We demonstrate that in habitual consumers high doses of caffeine can produce beneficial changes in visual attention. These results carry implications for the theorized interactions between caffeine, adenosine and dopamine in brain regions mediating visual attention.     

Communication,Influence, and Informational Asymmetries among Voters

The costs of political information vary dramatically across individuals, and these costs help explain why some individuals become politically expert while others demonstrate low levels of political knowledge and awareness. An attractive alternative, particularly for those with high information costs, is to rely on information and advice taken from others who are politically expert. This paper focuses on the complications that arise when the informant and the recipient do not share preferences. A series of small group experiments show that subjects tend to weight expertise more heavily than shared preferences in selecting informants, thereby exposing themselves to diverse views and biased information. Experimental subjects employ several heuristic devices in evaluating the reliability of this information, but depending on their own levels of information, these heuristics often lead subjects either to dismiss advice that conflicts with their own prior judgments or to dismiss advice that comes from an informant with divergent preferences. Hence these heuristics produce important consequences for patterns of political influence, as well as reducing the potential for political change.     

Impulse processing: a dynamical systems model of incremental eye movements in the visual world paradigm

The Visual World Paradigm (VWP) presents listeners with a challenging problem: They must integrate two disparate signals, the spoken language and the visual context, in support of action (e.g., complex movements of the eyes across a scene). We present Impulse Processing, a dynamical systems approach to incremental eye movements in the visual world that suggests a framework for integrating language, vision, and action generally. Our approach assumes that impulses driven by the language and the visual context impinge minutely on a dynamical landscape of attractors corresponding to the potential eye-movement behaviors of the system. We test three unique predictions of our approach in an empirical study in the VWP, and describe an implementation in an artificial neural network. We discuss the Impulse Processing framework in relation to other models of the VWP.     

Cognitive consequences of individual differences in arousal asymmetry

Prior research has demonstrated that semantic organization in the right hemisphere (RH) is more diffuse and specialized for distant semantic associates than is semantic organization in the left hemisphere (LH). The present research explored individual differences in this regard. If the RH is more specialized for distant semantic associates, then individuals with a more active RH should display greater activation of distant semantic associations. Two experiments were conducted to examine this issue. In both studies a line bisection task was used to assess arousal asymmetry. In Experiment 1, greater RH activation was associated with the ability to generate remote associates to three word stimuli. In Experiment 2, relatively greater RH activation was associated with enhanced priming of distant semantic associates. Taken together, these experiments demonstrate that arousal asymmetry is an individual difference variable that is related to variability in semantic organization and retrieval.     

Impact of negative affectively charged stimuli and response style on cognitive-control-related neural activation: An ERP study

The canonical AX-CPT task measures two forms of cognitive control: sustained goal-oriented control (“proactive” control) and transient changes in cognitive control following unexpected events (“reactive” control). We modified this task by adding negative and neutral International Affective Picture System (IAPS) pictures to assess the effects of negative emotion on these two forms of cognitive control. Proactive and reactive control styles were assessed based on measures of behavior and electrophysiology, including the N2 event-related potential component and source space activation (Low Resolution Tomography [LORETA]). We found slower reaction-times and greater DLPFC activation for negative relative to neutral stimuli. Additionally, we found that a proactive style of responding was related to less prefrontal activation (interpreted to reflect increased efficiency of processing) during actively maintained previously cued information and that a reactive style of responding was related to less prefrontal activation (interpreted to reflect increased efficiency of processing) during just-in-time environmentally triggered information. This pattern of results was evident in relatively neutral contexts, but in the face of negative emotion, these associations were not found, suggesting potential response style-by-emotion interaction effects on prefrontal neural activation.     

自我面孔识别的独特性

与识别他人的面孔相比,自我面孔识别在行为反应、种系发生、个体发展以及脑机制等方面都具有很大的独特性。行为指标方面,自我面孔识别在速度上快于识别他人的面孔;种系发生方面,只有人类和大猩猩等高级灵长类动物才具有识别自己面孔的能力;个体发展方面,儿童出生后不久即能识别他人面孔,但要在18个月左右才能表现出自我面孔识别能力;脑机制方面,神经心理学和脑成像研究结果表明自我面孔识别可能主要是右脑的功能。该领域的研究进展将为深入了解自我的形成机理提供一个新的探视“窗口”。     

Social psychology and social networks: Individuals and social systems

Social psychology and social network research are both centrally concerned with human sociality. Despite some historically significant interactions between the two, these areas of investigation have not been usefully deployed together in recent research endeavours. The present paper attempts to bring out some points of both theoretical and methodological contentions, to characterize the gap between them, to traverse briefly the trajectories of their historical development, and to provide some concrete instances of these differences. Intellectual resources available to Asian social psychology are reviewed, which may help bridge the gap between the two areas of research. We conclude by calling for a greater integration of social psychology and social network perspectives in future research.