Attentional prioritizations based on spatial probabilities can be maintained on multiple moving objects

Previous studies have shown that attention prioritizes locations that frequently contain a target. The present study examines whether these spatial prioritizations can be maintained on multiple independently moving objects. Observers viewed two line objects undergoing translational and rotational motion and detected probes appearing on the objects. The probabilities of probes appearing on the centers and ends of objects were manipulated. Experiment 1 showed that attention within moving objects is affected by location probabilities and is also heavily biased toward objects' centers. Experiment 2 showed that if the observer is not informed about location probabilities, the probabilities can be learned. Experiment 3 showed that with multiple-region objects, the center bias is reduced, but the effect of probabilities is unchanged. Experiment 4 showed that two distinct patterns of spatial prioritizations can be maintained on two objects simultaneously. These results suggest that attentional prioritizations based on spatial probabilities can occur in an object-based reference frame.