Response inhibition is a fundamental executive control function that enables humans to suppress actions that are inappropriate, unsafe, or inconsistent with current goals. The prevailing behavioral and computational account proposes that inhibition fails when the inhibitory process is simply too slow to intercept an initiated motor response. An alternative possibility that has been proposed but remained difficult to test is that some failures arise because the inhibitory process is never initiated; these hypothetical trials have been termed trigger failure (TF).
The abstract for this preprint frames the central question: are TF trials a real, identifiable subclass of inhibitory failures distinct from timing-based failures? The authors aimed to resolve this by developing an analytic approach capable of identifying individual TF trials and testing whether they differ behaviorally and neurally from other inhibitory failures.
The investigators combined three analytic strategies to detect TF trials in a large human sample (n = 253): Bayesian process-mixture modeling, likelihood ratio testing, and jackknife resampling. These methods were applied to behavioral and electrophysiological data to classify trials and to compare the properties of TF trials against other classes of inhibitory failure.
The source reports these analytic components in summary form; additional procedural and parameter details were not provided in the abstract.
Using the combined modeling and statistical approach, the authors report that TF trials can be identified at the level of individual trials in human participants. The modeling treated TF as a separate process within a mixture framework and used likelihood-based tests and jackknife resampling to validate trial-level classification.
This analytic strategy allowed the authors to move beyond theoretical discussion of TF and to empirically isolate trials consistent with a failure to launch the inhibitory process.
The analyses indicate that trigger failures represent a category of inhibitory failure that is behaviorally distinct from failures caused by a slow inhibitory process. Notably, TF trials do not arise from premature responses, differentiating them from other failed-stop trials that reflect too-rapid motor initiation relative to inhibition.
Thus, TF do not share the hallmark behavioral signature of timing-limited failures, supporting the interpretation that they reflect a different breakdown in executive control.
Electrophysiological data provide converging evidence: TF trials lack the stop-signal P3 event-related potential, a neural index commonly associated with engagement of the response inhibition process. The absence of this ERP component on TF trials supports the conclusion that the inhibitory mechanism was not triggered on those trials.
The combination of behavioral dissociation (no premature response signature) and the neural absence of the P3 yields a consistent picture in which TF reflect a true non-engagement of inhibition rather than a weaker or delayed inhibitory signal.
The authors report that TF do not result from perceptual or attentional lapses. That is, TF were not explained by failures to perceive the stop signal or by related attentional breakdowns, according to the analyses summarized in the abstract. This finding narrows plausible mechanisms for TF toward processes involved in initiating the inhibition command itself rather than sensory or attentional failures.
The study concludes that human response inhibition failures fall into at least two qualitatively distinct categories: those attributable to a slow inhibitory process that fails to stop an already initiated movement, and trigger failures in which the inhibitory process is not launched. The identification of TF at the single-trial level, their behavioral profile, and the absence of the stop-signal P3 together support TF as a distinct form of executive failure during response inhibition.
Recognizing separate failure modes has implications for theories of cognitive control and for interpreting behavioral and neural measures in clinical and experimental contexts. Distinguishing TF from timing-limited failures could influence how researchers link inhibitory deficits to clinical symptoms or to interventions that aim to enhance inhibitory control.
This work is presented as a bioRxiv preprint and has not been certified by peer review. The abstract reports the main analytic methods, sample size (253 humans), and key outcomes, but the source does not include detailed methods, full data, or peer-reviewed validation in the text provided here. Readers should consult the full preprint for complete methodological details and to assess robustness of the reported findings.
The authors declare no competing interests in the source material.