Spatial predictive cue of the stop-signal influences the probability of trigger failure

The ability to inhibit an action may depend on the timely detection of relevant environmental signals, such as a stop signal. Indeed, it has been shown, using a Stop Signal Task - in which stop signals occasionally appear and the subject must inhibit their response - that a spatial cue predictive of the stop signal's location enhances inhibitory performance (valid condition) compared to a condition where the cue is not predictive (invalid condition). Building on this finding, we asked whether this improved performance is explained by a simple speed up of inhibitory process or whether the inhibitory process is less likely to be triggered in the invalid condition. To address this issue, we used Bayesian Ex-Gaussian Estimation of Stop-Signal RT distributions (BEESTS) to estimate the probability of trigger failure and inhibitory process duration for each participant in both valid and invalid conditions (Matzke et al., 2017). We observed that trigger failures were significantly more frequent in the invalid condition compared to the valid condition, leading to an increased number of errors in stop trials. Conversely the duration of the inhibitory process estimated with the BEESTS method did not change between conditions. These findings highlight the importance of the detection process and its modulation by spatial attention in supporting effective inhibitory control. When the signal is not efficiently detected, the inhibitory process may fail to be triggered, thus impairing the ability to halt the response.