The impact and mechanism of gaze cues on object-based attention

Eye contact plays an important role in social interaction and can capture and hold attention. Previous studies have shown that eye contact can guide attentional allocation. However, a face with direct or averted gaze is a special object containing social information. The object's guidance for attentional allocation is called object-based attention, in which items in the cued object are processed more preferentially than items in the un-cued object. It is still unclear how eye contact interacts with objects in guiding attentional allocation. Therefore, the aim of the present study was to investigate the impact of eye contact and the cognitive mechanism of object-based attention. We conducted three experiments using the two-rectangle paradigm and objects with different gaze directions. In Experiment 1, faces were used as stimulus and to investigate whether and how eye contact interacted with face to guide attentional allocation. At the beginning of each trial, the fixation cross and two objects originally were displayed for 1000 ms on a screen. Then, a cue appeared randomly at any of the four ends of the two objects for 100 ms. After 0, 200, or 500 ms of inter-stimulus, the target appeared until the participant pressed the "M" key or remained on screen for 1500 ms. A black screen was then presented for 500 ms after each trial. During the experiment, the participants were asked to locate targets by pressing "M" as quickly as possible. We ruled out the influence of low-level features by using contrast reversed faces in Experiment 2. In Experiment 3, cups overlaid with eyes were used to explore whether the effect of eye contact still existed on real objects. The results of Experiment 1 revealed that there was a significant interaction between gaze directions, cue position, and stimulus onset asynchrony (SOA). Specifically, a larger object-based effect was discovered when the cue appeared on the direct-gaze face compared to the averted-gaze face under 300 ms SOA condition; however, there was no significant difference between them under 100 and 600 ms SOA conditions. Further analysis showed that the differences in object-based effect occurred because the participants reacted more quickly to the target in direct gaze than in averted gaze under the invalid same-object condition, which indicated that direct gaze could capture attention and cause a larger object-based effect. The difference in object-based effect between direct and averted gaze at 300 ins SOA disappeared in Experiment 2. The results of Experiment 3 replicated the results of Experiment 1 and further demonstrated that the influence of eye contact on object-based attention could extend to real objects. In conclusion, the present study extends the extant literature in several dimensions. First, it provides the first evidence, to the best of our knowledge, that eye contact interacts with objects, including faces and cups, in guiding attentional allocation. The top-down processing of eye contact facilitates the processing of objects under an invalid same-object location, which leads to greater object-based attention and supports the sensory enhancement theory. Second, it also reveals that the influence of eye contact on object-based attention is regulated by SOA.