Stimulus novelty and intraseries primacy in GSR adaptation

GSR records were obtained for four groups of 20 Ss. Group I was presented with a series of four different lights (amber, blue, green, and white) appearing 20 times each, in apparent random order. The procedure was similar for the other three groups except that in group 2, a novel stimulus (a red light) appeared instead of the sixth amber light; in group 3, it appeared instead of the 16th amber light; and, in group 4, it appeared instead of the 16th amber light. Typical GSR adaptation phenomena were observed in all groups. The introduction of the novel stimulus appeared to have no effect on the course of GSR adaptation.     

Ipsi-and bilateral interactions in taste

In two experiments, the integration over spatial extent in taste was investigated for threshold sensitivity to NaCl and for suprathreshold intensity perception of saltiness. The area of stimulation was doubled by adding either an ipsilateral or a bilateral stimulus. The two stimuli could be of equal or unequal intensity. The data showed that at threshold level a probability summation model applied to all bilateral and most of the ipsilateral stimulus combinations. Probability summation failed to predict detection probability when two stimuli with different intensities were presented at the same tongue side. For suprathreshold stimuli, the magnitude of the saltiness sensation as estimated by a line-length method depended on the level of stimulation. The possible peripheral interaction mechanisms and central factors contributing to the taste response were discussed.     

The integration of knowledge and experimentation strategies in understanding a physical system

This study investigated how people integrate different kinds of knowledge in coming to understand the functions of components of a physical system. Twenty-three undergraduates worked on a hypothesis-testing task in which they constructed test circuits to decide the identity of electrical components hidden inside boxes. The students' problem-solving was driven by qualitative causal models that included ideas about cause and effect, task demands, and functions of circuits and circuit components. There was a hierarchy of four causal models, with higher levels representing increasing understanding and supporting increasingly successful problem solution. These causal models were associated with characteristic experimentation strategies, including strategies for generating evidence, interpreting evidence, and managing memory requirements. Some of these strategies followed directly from the causal model a student held, whereas others appeared to be more general. The level of understanding a student eventually attained about this physical system was a function of both domain knowledge and proficiency in experimentation strategies.     

The effect of change in sequential visual stimuli on GSR adaptation: II,the novel stimulus as a disinhibiting stimulus

GSR records were obtained for 20 Ss presented with a series of 80 stimuli (four lights alternating in apparent random sequence). Records were obtained, also, for 20 Ss in each of two groups, using the same procedure: in Group 1, a tone was substituted for one of the lights, early in the sequence, and in Group 2, it was substituted later in the sequence. The tone, the novel stimulus, produced significant changes in the GSR adaptation patterns of the two groups.     

What to do and how to do it: sequence learning of action effects and transformation rules

Many goal-oriented actions, for example in tool use, can be characterized by the involvement of two components: The effect that the acting person wants to achieve and the transformation rule that defines the relationship between a bodily movement and the associated action effect. Both in conjunction specify the concrete action that has to be executed. In our experiments, we utilized a sequence learning paradigm to investigate whether these components are represented separately or are bound together to form a more holistic representation of the action. Participants switched between different transformation rules to achieve certain action effects. In one group, there was a fixed sequence of action effects, with randomly varying transformation rules. In the other group, the sequence of transformation rules was fixed, whereas the action effects were randomly varying. Results indicate that both kinds of sequences can be learned and provide evidence for the notion that transformation rules and action effects are represented separately.     

Using FMRI to test models of complex cognition

This article investigates the potential of fMRI to test assumptions about different components in models of complex cognitive tasks. If the components of a model can be associated with specific brain regions, one can make predictions for the temporal course of the BOLD response in these regions. An event-locked procedure is described for dealing with temporal variability and bringing model runs and individual data trials into alignment. Statistical methods for testing the model are described that deal with the scan-to-scan correlations in the errors of measurement of the BOLD signal. This approach is illustrated using a "sacrificial" ACT-R model that involves mapping 6 modules onto 6 brain regions in an experiment from Ravizza, Anderson, and Carter (in press) concerned with equation solving. The model's visual encoding predicted the BOLD response in the fusiform gyrus, its controlled retrieval predicted the BOLD response in the lateral inferior prefrontal cortex, and its subgoal setting predicted the BOLD response in the anterior cingulate cortex. On the other hand, its motor programming failed to predict anticipatory activation in the motor cortex, its representational changes failed to predicted the pattern of activity in the posterior parietal cortex, and its procedural component failed to predict an initial spike in caudate. The results illustrate the power of such data to direct the development of a theory of complex problem solving, both at the level of a specific task model as well as at the level of the cognitive architecture.     

Young German children's early syntactic competence: a preferential looking study

Using a preferential looking methodology with novel verbs, Gertner, Fisher and Eisengart (2006) found that 21-month-old English children seemed to understand the syntactic marking of transitive word order in an abstract, verb-general way. In the current study we tested whether young German children of this same age have this same understanding. Following Gertner et al. (2006), one group of German children was tested only after they had received a training/practice phase containing transitive sentences with familiar verbs and the exact same nouns as those used at test. A second group was tested after a training/practice phase consisting only of familiar verbs, without the nouns used at test. Only the group of children with the training on full transitive sentences was successful in the test. These findings suggest that for children this young to succeed in this test of syntactic understanding, they must first have some kind of relevant linguistic experience immediately prior to testing--which raises the question of the nature of children's linguistic representations at this early point in development.     

Cultural Background and Individualistic–Collectivistic Values in Relation to Similarity, Perspective Taking, and Empathy

A path model testing antecedents and consequences of perceived similarity was examined for Asian and European Australian participants ( N  = 240). Cultural background and values were measured, and participants read scenarios describing a target in distress acting according to individualistic or collectivistic values. Consistent with past research, feeling similar to the target was linked to perspective taking and empathy. Moreover, Asian participants were more collectivistic, and collectivistic values were linked to higher empathy. In the present data, however, both endorsed higher levels of collectivism than individualism; individualism scores were equal; and the two values were positively correlated. Moreover, neither cultural background nor values were consistently linked to similarity. Implications are discussed for research on cultural background, values, and social interactions.     

Effects of repetitive stress during the acute phase of Trypanosoma cruzi infection on chronic Chagas' disease in rats

The effect of repetitive stress during acute infection with Trypanosoma cruzi (T. cruzi) on the chronic phase of ensuing Chagas' disease was the focus of this investigation. The aim of this study was to evaluate in Wistar rats the influence of repetitive stress during the acute phase of infection (7 days) with the Y strain of T. cruzi on the chronic phase of the infection (at 180 days). Exposure to ether vapor for 1 min twice a day was used as a stressor. Repetitive stress enhanced the number of circulating parasites and cardiac tissue disorganization, from a moderate to a severe diffuse mononuclear inflammatory process and the presence of amastigote burden in the cardiac fibers. Immunological parameters revealed that repetitive stress triggered a reduced concanavalin A induced splenocyte proliferation in vitro with major effects on the late chronic phase. Serum interleukin-12 concentration decreased in both stressed and infected rats in the early phase of infection although it was higher on 180 days post-infection. These results suggest that repetitive stress can markedly impair the host's immune system and enhance the pathological process during the chronic phase of Chagas' disease.