Causes of IOR
Posner and Cohen proposed three explanations for inhibition: 1) inhibition results from having two alternative positions, 2) inhibition could result from moving attention away from a cued stimulus back to the fixation point, and 3) inhibition may occur because the efficiency in some part of the pathway from the cued location is reduced by the cuing.
An alternative explanation of IOR is that IOR occurs after attention has been disengaged from the cued stimulus, resulting in a delayed response back to that cued stimulus. This occurs because it inhibits an individual from reorienting back to a stimulus they previously attended to.
It has also been suggested that IOR is activated by midbrain oculomotor pathways. Others believe that IOR is caused by both a delay in activation of attentional and motor processes.
Read more about this topic: Inhibition Of Return