| Abstract: | An inhibitory control is exerted when the context in which a movement has been planned changes abruptly making the impending movement inappropriate. Neurons in the frontal eye field and superior colliculus steadily increase activity before a saccadic eye movement, but cease the rise below a threshold when an impending saccade is withheld in response to an unexpected stop‐signal. This type of neural modulation has been majorly considered as an outcome of a race between preparatory and inhibitory processes ramping up to reach a decision criterion. An alternative model claims that the rate of saccade planning is diminished exclusively when the stop‐signal is detected within a stipulated period. However, due to a dearth of empirical evidence in support of the latter model, it remains unclear how the detectability of the stop‐signal influences saccade inhibition. In our study, human participants selected a visual target to look at by discriminating a go‐cue. Infrequently they cancelled saccade and reported whether they saw the stop‐signal. The go‐cue and stop‐signal both were embedded in a stream of irrelevant stimuli presented in rapid succession. Participants exhibited difficulty in detection of the stop‐signal when presented almost immediately after the go‐cue. We found a robust relationship between the detectability of the stop‐signal and the odds of saccade inhibition. Saccade latency increased exponentially with the maximum time available for processing the stop‐signal before gaze shifted. A model in which the stop‐signal onset spontaneously decelerated progressive saccade planning with the magnitude proportional to its detectability accounted for the data. |
