The claim defended in the paper is that the mechanistic account of explanation can easily embrace idealization in big-scale brain simulations, and that only causally relevant detail should be present in explanatory models. The claim is illustrated with two methodologically different models: Blue Brain, used for particular simulations of the cortical column in hybrid models, and Eliasmith’s SPAUN model that is both biologically realistic and able to explain eight different tasks. By drawing on the mechanistic theory of computational explanation, I (...) argue that large-scale simulations require that the explanandum phenomenon is identified; otherwise, the explanatory value of such explanations is difficult to establish, and testing the model empirically by comparing its behavior with the explanandum remains practically impossible. The completeness of the explanation, and hence of the explanatory value of the explanatory model, is to be assessed vis-à-vis the explanandum phenomenon, which is not to be conflated with raw observational data and may be idealized. I argue that idealizations, which include building models of a single phenomenon displayed by multi-functional mechanisms, lumping together multiple factors in a single causal variable, simplifying the causal structure of the mechanisms, and multi-model integration, are indispensable for complex systems such as brains; otherwise, the model may be as complex as the explanandum phenomenon, which would make it prone to so-called Bonini paradox. I conclude by enumerating dimensions of empirical validation of explanatory models according to new mechanism, which are given in a form of a “checklist” for a modeler. (shrink)

Stressful life situations can impair or facilitate various cognitive functions. In the present study, the effect of examination stress on students was examined using two executive function tasks, task-switching and the Stroop task, in a between-subject crossover design. Students showed increased anxiety in the 2 week period prior to exams compared to the beginning of the semester, manifested as higher scores on the Spielberger State-Trait Anxiety Scale and a shift to more sympathetic activation when heart rate variability was assessed. During (...) the stressful period, the switching cost was reduced on a spatial task-switching paradigm and reaction times in the Stroop task were faster. This is the first study to show stress-induced facilitation of performance on these executive function tasks. (shrink)

Depression has been linked with impaired executive control and specific impairments in inhibition of negative material. To date, only a few studies have examined the relationship between depressive symptoms and executive functions in response to emotional information. Using a new paradigm, the Affective Shift Task (AST), the present study examined whether depressive symptoms in general, and rumination specifically, are related to impairments in inhibition and set shifting in response to emotional and non-emotional material. The main finding was that depressive symptoms (...) in general were not related to inhibition. Set-shifting impairments were only observed in moderate to severely depressed individuals. Interestingly, rumination was related to inhibition impairments, specifically when processing negative information, as well as impaired set shifting as reflected in a larger shift cost. These results are discussed in relation to cognitive views on vulnerability for depression. (shrink)

Goal‐directed cognition is often discussed in terms of specialized memory structures like the “goal stack.” The goal‐activation model presented here analyzes goal‐directed cognition in terms of the general memory constructs of activation and associative priming. The model embodies three predictive constraints: (1) the interference level, which arises from residual memory for old goals; (1) the strengthening constraint, which makes predictions about time to encode a new goal; and (3) the priming constraint, which makes predictions about the role of cues in (...) retrieving pending goals. These constraints are formulated algebraically and tested through simulation of latency and error data from the Tower of Hanoi, a means‐ends puzzle that depends heavily on suspension and resumption of goals. Implications of the model for understanding intention superiority, postcompletion error, and effects of task interruption are discussed. (shrink)