Intrusive effects of semantic information on visual selective attention

Every object contains semantic information in extension to its low-level properties. It is well documented that such information biases attention when it is necessary for an ongoing task. However, whether semantic relationships influence attentional selection when they are irrelevant to the ongoing task remains an open question. The ubiquitous nature of semantic information suggests that it could bias attention even when these properties are irrelevant. In the present study, three objects appeared on screen, two of which were semantically related. After a varying time interval, a target or distractor appeared on top of each object. The objects’ semantic relationships never predicted target location. Despite this, a semantic bias on attentional allocation was observed with an initial, transient bias to semantically related objects. Further experiments demonstrated that this effect was contingent on the objects being attended: if an object never contained the target, it no longer exerted a semantic influence. In a final set of experiments, we demonstrate that semantic bias is robust and appears even in the presence of more predictive cues (spatial probability). The results suggest that as long as an object is attended, its semantic properties bias attention, even if it is irrelevant to an ongoing task and there are more predictive factors available.