Object-based attention occurs regardless of object awareness

In this study, we investigated whether awareness of objects is necessary for object-based guidance of attention. We used the two-rectangle method (Egly, Driver, & Rafal, 1994) to probe object-based attention and adopted the continuous flash suppression technique (Tsuchiya & Koch, 2005) to control for the visibility of the two rectangles. Our results show that object-based attention, as indexed by the same-object advantage—faster response to a target within a cued object than within a noncued object—was obtained regardless of participants’ awareness of the objects. This study provides the first evidence of object-based attention under unconscious conditions by showing that the selection unit of attention can be at an object level even when these objects are invisible—a level higher than the previous evidence for a subliminally cued location. We suggest that object-based attentional guidance plays a fundamental role of binding features in both the conscious and unconscious mind.