Optimality Conditions for Semivectorial Bilevel Convex Optimal Control Problems

We present optimality conditions for bilevel optimal control problems where the upper level is a scalar optimal control problem to be solved by a leader and the lower level is a multiobjective convex optimal control problem to be solved by several followers acting in a cooperative way inside the greatest coalition and choosing amongst efficient optimal controls. We deal with the so-called optimistic case, when the followers are assumed to choose the best choice for the leader amongst their best responses, as well with the so-called pessimistic case, when the best response chosen by the followers can be the worst choice for the leader. This paper continues the research initiated in Bonnel (SIAM J. Control Optim. 50(6), 3224-3241, 2012) where existence results for these problems have been obtained. © Springer Science+Business Media New York 2013

Contrasting effects of sensory limits and capacity limits in visual selective attention

The effects of perceptual load and those of target-stimulus degradation on distractor processing were contrasted. Targets either had to be found among several nontargets (high perceptual load) or were presented alone and were intact (low perceptual load), had reduced size and contrast (Experiment 1), had reduced duration and were followed by a mask (Experiment 2), or had reduced visual acuity owing to position eccentricity (Experiment 3) in thedegraded low-load condition. The results showed that both high perceptual load and target degradation increased general task difficulty, as is reflected by overall reaction times and accuracy. However, whereas high perceptual load reduced response-competition effects of irrelevant distractors, target degradation increased distractor effects. These results support the hypothesis that distractor processing depends on the extent to which high perceptual load exhausts attention in relevant processing, and provide a dissociation between perceptual load and general task difficulty and processing speed