It has been suggested that both task-relevant and task-irrelevant VPL at least partially result from interactions between reinforcement signals and bottom-up signals from the presented feature,irrespective of whether the feature is task relevant or task irrelevant (Seitz & Watanabe 2005).However, different aspects of mechanisms seem to be involved in these two types of VPL. One aspect is the differential effects of attentional control. A task-relevant feature is enhanced by attention, whereas task-irrelevant features may be suppressed if the features are suprathreshold and are detected by the attentional system