If one is asked to list all the characteristics that describe or do not describe an individual or object, most !people would list more characteristics with less mental effort in the former case than in the latter even though there are more characteristics that do not than those that do describe the stimulus. This asymmetry exists because people are better able to think affirmationally than negationally. From an evolutionary perspective, the ability to discern what an organism is--whether a newcomer is hostile, a potential partner is solicitous, a potential ally is captious, or a child is dependentmis more important for reproductive success than is the ability to discern the innumerable characteristics that do not describe each. The present proposal builds on two related asymmetries in human affective information processing that we have studied: the positivity offset and the negativity bias. Recently, we have identified individual differences in the expression of these biases, which we gauge using incidental measures.
Specific Aim #1 builds on our prior work to test the relationship between the positivity offset or negativity bias and a set of psychophysiological assessments linked previously to affective processes in several other projects in this application.
Specific Aim #2 is designed to examine these affective asymmetries from the perspective of associated neural mechanisms using fMRI. Three experimental procedures with overlapping affective information processes have been developed to elicit the positivity offset and negativity bias, and these procedures will be used to identify converging regions of activation associated with the positivity offset and negativity bias. Furthermore, half the tasks require affective (good/bad) judgments and half require nonaffective (social/nonsocial) judgments of the stimuli. Contrasts isolating the positivity offset or negativity bias that are significant in both tasks suggest neural substrates for automatic component processes, whereas contrasts that are significant only when affective judgments are explicit suggest neural substrates for non-automatic component processes.
Specific Aim #3 is to investigate how the implicit measures of the positivity offset and negativity bias differentiate among three groups of individuals: depressed, anxious, and age, ethnicity, &gender-matched healthy controls. Specifically, we propose to investigate how individual differences in positivity offset and negativity bias differentiate affective style within the context of specific psychiatric conditions.
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