Beyond mixed alerting signals: Disentangling phasic from tonic influences on visual attention and cognitive control.

Alertness plays a critical role in sensory processing, yet the extent to which phasic (transient) and tonic (sustained) alertness interact in shaping attention and cognitive control of attention (top-down control) remains unclear. We report two preregistered experiments, designed to disentangle and examine the specific effects of phasic and tonic alerting on distinct attentional processes, independent of motor responses. Using a phasic/tonic/no-alerting design with a purely accuracy-based letter recognition task, we apply computational modeling to analyze whether alerting influences perceptual thresholds, processing speed, visual short-term memory, spatial weighting, and top-down control. Results show that phasic alerting significantly enhances visual processing speed without affecting other attentional parameters, including top-down control. These results suggest that, in the absence of motor confounds, the interaction between alerting and cognitive control may be more limited than previously assumed in Posner and colleagues' attention network theory. In addition, results show that exposure to phasic alerting does not influence tonic alertness levels. This dissociation establishes a novel, methodological framework for isolating phasic alerting effects in attentional tasks, free from tonic confounds. Our findings highlight the distinct role of phasic alerting in accelerating visual processing globally rather than selectively, thus advancing our understanding of attentional dynamics in complex environments. (PsycInfo Database Record (c) 2026 APA, all rights reserved).