Inhibition of return in saccadic eye movements

Inhibition of return (IOR) is a phenomenon in which responses generated to targets at previously attended locations are delayed. It has been suggested that IOR affords a mechanism for optimizing the inspection of novel locati ons and that it is generated by oculomotor reflexes mediated by the superio r colliculus, In this investigation, we measured the effects of IOR on the metrics of saccadic eye movements made to novel and previously attended loc ations. Saccades made to cued target locations, as well as to other targets within the same hemifield, had longer latencies than saccades made towards the novel, uncued hemifield. We further found that the amplitudes of sacca des towards the cued hemifield were more hypometric, but only when the ampl itude could not be pre-programmed. These results provide evidence that IOR influences spatial, as well as temporal, parameters of saccadic eye movemen ts and suggest that the exogenous orienting of attention, in addition to in fluencing target detection, also influences oculomotor programming.