Does the output form of inhibition of return operate at or after the bottleneck?

Inhibition of return (IOR) refers to the longer reaction times (RTs) to targets presented at previously cued, fixated or attended locations. It has been suggested that there are two distinct forms of IOR. The input form, generated when the reflexive oculomotor system is suppressed, affects the sensory/perceptual processing. The output form, generated when the reflexive oculomotor system is not suppressed, biases responding. It has been demonstrated, using the locus of slack logic associated with the psychological refractory period (Pashler, 1998),that the input form of IOR operates on a pre-bottleneck stage of processing, Kavyani et al. (2017). Using the same logic, Klein et al. (2020) demonstrated that the output form of IOR operates at or after the bottleneck. Building on the methods of Klein et al. the present study used PRP paradigm to determine whether the output form of IOR operates at or after the bottleneck. The output form of IOR was generated by an initial saccade from a peripheral location to a central fixation point. Task 1 consisted of a manual response indicating the location (right/left) of a subsequent visual stimulus. Task 2 required participants to discriminate the frequency (high/low) of an auditory stimulus and make a key-press response with their other hand. The targets (T1 and T2) for the two tasks were presented in close succession with 200, 400 and 800 ms target-target onset asynchronies (TTOAs). Responses to T1 were delayed by IOR and responses to T2 were substantially delayed when the TTOA was brief. Statistical analysis of the amount of carry over of the IOR effect experienced by Task 1 onto the RTs for Task 2 strongly suggest that the output form of IOR operates after the bottleneck. Nevertheless, aspects of the results could be interpreted to support a weaker influence of IOR operating also at the bottleneck stage of processing.