Cognitive interference and aging: insights from a spatial stimulus-response consistency task

One hundred and thirty-one adults belonging to four age groups (19-26, 50-59, 60-69 and 70-82 years) performed a spatial stimulus-response consistency task in which the response dimension (left or right) overlapped relevant and irrelevant stimulus dimensions. The influence of the irrelevant stimulus dimension on response time was significantly greater in the middle age groups than among 19-26 year-olds, and significantly greater in the highest age group than in any other. This pattern persisted when allowance was made for a significant age-related increase in processing time (measured as reaction time in a single-stimulus, single-response task). It is concluded that in tasks of the kind used, the elderly resist interference from the irrelevant information less easily than do younger persons. Interestingly, comparison of Vincentized quintiles suggested that the effect of the irrelevant stimulus dimension decreased with increasing response time among 19-26 year-olds, but increased with response time among 70-82 year-olds.     

A measure of racial identity in African American adolescents: the development of the Multidimensional Inventory of Black Identity--Teen

The Multidimensional Inventory of Black Identity--Teen (MIBI--T) is designed to assess the 3 cross-situationally stable dimensions (centrality, regard, and ideology) of the Multidimensional Model of Racial Identity (MMRI; R. M. Sellers, M. A. Smith, J. N. Shelton, S. A. J. Rowley, & T. M. Chavous, 1998) within teenagers. Adolescent responses (n= 489) to the MIBI--T were subjected to several analyses to evaluate the psychometric character of the measure. Findings indicated that the MIBI--T represents a valid framework for African American adolescents. Its internal structure is consistent with the conceptual framework of the MMRI, and findings support its construct validity. Results also indicate model invariance across grade level and gender, as well as suggest evidence of predictive validity. Further information about the MIBI--T and the full set of items are presented.     

Self‐framing of risky choice

Previous research on framing effects has largely focused on how choice information framed by external sources influences the response of a decision maker. This research examined how decision makers framed choice options and how the hedonic tone of self‐framing influenced their risk preference. By using pie charts and a complementary sentence‐completion task in Experiment 1, participants were able to interpret and frame the expected choice outcomes themselves before making a choice between a sure option and a gamble in either a life–death or a monetary problem. Each of these self‐frames (phrases) was then rated by a group of independent judges in terms of its hedonic tone. The hedonic tone of self‐frames was mostly positive and was more positive in the life–death than the monetary context, suggesting a motivational function of self‐framing. However, positive outcomes were still more likely to be framed positively than negative outcomes. In Experiment 2, choice outcomes were depicted with a whole‐pie chart instead of a pie slice in order to emphasize positive and negative outcomes equally. The results showed that the hedonic tone of self‐framing was still largely positive and more positive in the life domain than the monetary domain. However, compared to Experiment 1, the risk preference in the life–death domain was reversed, showing an outcome salience effect: when the pie‐slice chart emphasized only survival outcomes, participants were more risk taking under positive hedonic frames whereas when the whole‐pie chart depicted both survival and mortality outcomes, they became risk averse under positive frames. In sum, self‐framing reflected a positive bias in encoding risk information and affected the risk preference of the decision maker. Like the tone of voice used in communication, the hedonic tone of self‐framing, either positive or negative, can affect risk perception of a choice problem. Copyright © 2003 John Wiley & Sons, Ltd.     

Leverpress escape/avoidance conditioning in rats: Safety signal length and avoidance performance

Leverpress escape/avoidance is an excellent model for assessing coping in rats. Acquisition of the leverpress response is determined by the interstimulus (signal-shock) interval, as well as the type and duration of the aversive event. One factor that has received less research attention is the safety or feedback signal. The safety signal presumably negatively reinforces leverpress responding through fear reduction. Here, we present a parametric manipulation of safety signal length and avoidance performance. All rats were trained with a 60-s tone conditioned stimulus and an intermittent 1-s, 1.0-mA footshock. Training was further accomplished with a 1−, 2−, 4−, or 6-min safety signal. Acquisition of the avoidance response was comparable at all safety signal durations. Rats trained with the shortest safety signal (1 min) exhibited more leverpresses during the safe period, a measure of anxiety. Thus, acquisition of the leverpress avoidance response was efficient regardless of safety signal duration, even though shorter periods were associated with greater anxiety.     

Developmental shifts in fMRI activations during visuospatial relational reasoning

To investigate maturational plasticity of fluid cognition systems, functional brain imaging was undertaken in healthy 8-19 year old participants while completing visuospatial relational reasoning problems similar to Raven's matrices and current elementary grade math textbooks. Analyses revealed that visuospatial relational reasoning across this developmental age range recruited activations in the superior parietal cortices most prominently, the dorsolateral prefrontal, occipital-temporal, and premotor/supplementary cortices, the basal ganglia, and insula. There were comparable activity volumes in left and right hemispheres for nearly all of these regions. Regression analyses indicated increasing activity predominantly in the superior parietal lobes with developmental age. In contrast, multiple anterior neural systems showed significantly less activity with age, including dorsolateral and ventrolateral prefrontal, paracentral, and insula cortices bilaterally, basal ganglia, and particularly large clusters in the midline anterior cingulate/medial frontal cortex, left middle cingulate/supplementary motor cortex, left insula-putamen, and left caudate. Findings suggest that neuromaturational changes associated with visuospatial relational reasoning shift from a more widespread fronto-cingulate-striatal pattern in childhood to predominant parieto-frontal activation pattern in late adolescence.     

Aphasics' sensitivity to contextual appropriateness conditions for pragmatic indicators

Twenty normal and twenty aphasic subjects were tested for their understanding of implicit meanings of the French adverbs même (even), aussi (also), and surtout (mainly). Their sensitivity to the contextual appropriateness conditions of such items was analyzed in a multiple-choice paradigm requiring them to select from three figures the one which was best described by a sentence like "Show me the figure that is même (aussi, surtout) red." A global quantitative comparison indicates that aphasics' performance was inferior to that of the normal controls. Yet, the analysis of individual responses allowed the identification of three different subgroups of aphasics: the first produced responses identical to the normals' responses; the second seemed to ignore the adverb and systematically selected the figure with the highest amount of the asserted color; and the third produced responses identical to the normals' responses for surtout but had difficulties with même or aussi. As concerns the relationship between aphasics' performance and their scores on literal language comprehension tests, the data favor the dissociation between literal and pragmatic factors in comprehension. Finally, no clear relationship was observed between aphasia type and aphasics' performance, although three points are noted in the discussion: (1) all the conduction aphasics performed like normals, (2) among the Broca's aphasics, the one with the clearest agrammatic verbal output produced responses similar to those of the normals, and (3) there was no anomic patient in the second subgroup.     

Conspiracy theories on the basis of the evidence

Synthese - Conspiracy theories are often portrayed as unwarranted beliefs, typically supported by suspicious kinds of evidence. Yet contemporary work in Philosophy argues provisional belief in...