Solving the paradox between same-object advantage and different-object advantage

- Benefit or cost of the object effect is determined by identicality of targets.
- Same object advantage effect appears when two targets are clearly different.
- Different object advantage effect occurs when two targets are identical.

The same-object advantage (SOA) effect is usually cited as evidence for object-based attention. However, the different-object advantage (DOA) effect, which appears to be the opposite of the SOA effect, has also been reported by some researchers. The present study was designed to resolve this apparent inconsistency. As the SOA effect has been well documented, here we focus on exploring when and why the DOA effect occurs. With a series of four experiments, we manipulated the identicality between two targets and found the SOA effect when the targets were different but the DOA effect when they were identical. These results demonstrate that the presence of SOA vs. DOA effects can be critically determined by the identicality between targets. Moreover, Experiment 4 provides direct evidence for our hypothesis that the DOA effect arises from the benefit of placing two identical targets in distinct objects (e.g., rectangles) that can help the differentiation between targets.