Where has object-based IOR gone?

We sought to investigate the putative object-based and location-based components of the inhibition of the return (IOR) of attention. In Exp. 1, we drew attention first to one of four boxes arranged around a center box and then back to the center. (Boxes differed in color so each could be distinguished as a different object.) Next, we drew attention to the center box and rotated the peripheral boxes 90° before presenting a target. Latencies were longer to detect targets appearing at the initially cued location than at uncued locations (p < 0.01), but no differences were observed at the final location of the cued object box. Thus, Exp. 1 revealed location-based, but not object-based IOR. In Exp. 2 we rotated the peripheral boxes 90° before drawing attention back to the center. After the motion stopped, we drew attention back to the center before presenting the target. Now, we observed IOR at both the original cued location and the location to which the cued box moved (p < 0.01). We interpret the results of Exp. 2 as location-based IOR rather than object-based IOR. We consider the possibility that IOR is predominantly location-based. Abstract