An attentional limbo: Between saliency-driven and goal-driven selection, saccades become momentarily non-selective.

Both saliency and goal information are important factors in driving visual selection. Previous work has shown that these processes follow different time courses: saliency-driven selection prevails shortly after the presentation of the onset of the visual scene, after which goal-driven biases towards task-relevant stimuli take over. Here, we report evidence for an intermediate period during which eye movements appear to be neither driven by saliency nor by the task goal. We used a simple selection task in which we presented either a salient target with a non-salient distractor, or a non-salient target with a salient distractor. Subjects were asked to make a speeded eye movement to the target. In line with previous findings, we found that short-latency saccades were driven by saliency, whereas long-latency saccades were driven by task relevance. Strikingly, in between these different selection episodes, we observed a time window of a few tens of milliseconds during which eye movements were neither driven by saliency nor by relevance. During this “attentional limbo”, subjects were equally likely to select the non-salient distractor as they were to select the salient target. We show this for saliency and relevance defined within the same dimension (orientation ) and within different dimensions (orientation and color). Furthermore, we show that the onset of this period of non-selectivity is modulated by eccentricity. We hypothesize that during this time window of non-selectivity initial signal processing of the salient and non-salient item have both completed, thus eliminating the relative saliency effect, while differential goal-driven modulation has not yet started. In this period, the eyes momentarily rely on information regarding signal presence, without being biased by saliency and goals.