Attention hijacked: How social media notifications disrupt cognitive processing

Digital notifications are ubiquitous in modern life, yet their impact on cognitive performance remains poorly understood. Here, we introduce an ecologically valid paradigm to examine how social media notifications disrupt ongoing task performance. Participants completed a Stroop task while receiving smartphone-style notifications, allowing us to track both behavioural and physiological responses. Notifications triggered a transient slowdown in cognitive processing lasting approximately seven seconds, driven by the combined influence of perceptual salience, learned associations, and relevance appraisal. The magnitude of this disruption was predicted by the inferred relevance of notifications and by individual patterns of smartphone use—specifically, the frequency of interaction (notification volume and checking behaviour) rather than total time spent on the device. These findings were mirrored in changes in pupil dilation, a physiological marker of cognitive load, confirming the convergent impact of notification relevance and smartphone habits. Together, our results show that modern digital cues can hijack attentional resources, even in the absence of explicit personal relevance. They underscore the need to account for notification frequency—not merely screen time—when evaluating the cognitive cost of pervasive digital environments, and raise broader concerns about the long-term impact of habitual device interaction on attentional functioning.