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The literature has long emphasized the neocortex's role in the tangled phasic-alertness and temporal-expectancy processes. In this work, we examined whether subcortical, monocular mechanisms have a functional role in these processes. This was done by assessing phasic alertness and temporal expectancy independently using a cue-target eye-of-origin manipulation. Participants performed target detection tasks in which a central cue and its ensuing peripheral target were each presented either to the same eye or to a different eye. In Experiment 1, phasic alertness, independent of temporal expectancy, was manipulated by presenting an alerting cue prior to the target presentation. The alerting effect elicited by the cue lasted for a longer duration when the cue and target were presented to the same eye than when they were presented to different eyes, indicating the involvement of subcortical regions in phasic alertness. In Experiment 2, the cue's temporal predictability regarding the target's onset time was manipulated by changing the cue-target interval's foreperiod distribution. A modulation in temporal expectancy was found when both the cue and the target were presented to the same eye, demonstrating the importance of subcortical mechanisms in temporal expectancy. Together, the results demonstrate that monocular channels are functionally involved in both phasic alertness and temporal expectancy. This study suggests that both phasic alertness and temporal expectancy are functionally dependent on monocular channels of the visual stream, and highlights the importance of direct examination of primitive, subcortical regions in higher cognitive functioning (e.g., temporal expectancy).

In recent years, studies have revealed an interaction between two systems of attention-alerting and executive control. Specifically, warning cues increase the influence of cognitive conflict under certain conditions. One of the problems of interpreting this effect is that warning cues can trigger two processes simultaneously-a high arousal state and strategic temporal expectancy. The goal of the present study was to clarify which process underlies the increased congruency effects following a warning event. In two experiments, the influence of warning cues on flanker congruency was examined while controlling for the effects of temporal expectancy and arousal. Experiment 1 revealed a strong effect of warning cues on congruency, even when the warning cues were not temporally predictive. This effect was evident at two short cue-to-target intervals of 100 and 500 ms, but not following a 900-ms interval. Experiment 2 revealed that this effect was not altered even when the warning cues predicted with high certainty that the target would appear at long cue-to-target intervals (e.g., 900 ms). We suggest that the interaction between alerting and executive control reflects the involvement of a subcortical mechanism responsible for increasing arousal.