In today’s digital work environments, employees are frequently required to manage multiple tasks while simultaneously responding to a stream of digital notifications. While multitasking and interruptions are often seen as necessary for productivity, research suggests that they may significantly impair task performance and cognitive efficiency. To investigate this issue, the present study examines how multitasking and varying levels of digital interruption intensity affect task accuracy, efficiency, and cognitive workload.
Grounded in Cognitive Load Theory, Memory for Goals Theory, and Attention Residue Theory, this research adopts a within-subject experimental design involving 62 participants. Each participant completed four conditions in randomized order: (1) single-tasking, (2) multitasking without interruption, (3) multitasking with low interruptions, and (4) multitasking with high interruptions. Cognitive workload was measured using NASA-TLX, while attention and effort were tracked using real-time eye-tracking data including fixation duration, fixation count, scanpath length, and pupil diameter. In addition, participants’ baseline multitasking tendencies were measured using the Media Multitasking Index (MMI) and included as a covariate to control for individual differences. MMI did not exhibit a significant moderating effect, suggesting that the negative impacts of multitasking and interruptions are consistent regardless of prior multitasking habits.
Specifically, the results reveal that multitasking significantly reduces task performance compared to single-tasking. Furthermore, the presence of digital interruptions leads to additional cognitive load and degraded performance, particularly under high-intensity conditions. Notably, eye-tracking metrics show a consistent increase in visual effort and attention dispersion as task complexity increases. These findings support all proposed hypotheses and highlight the compounded cognitive cost of multitasking in modern digital contexts. Consequently, the study contributes both theoretically and practically by offering empirical insights into how workplace multitasking and interruptions undermine cognitive performance and by informing the design of interruption-aware digital systems.

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