The cognitive mechanism underlying high performance during decision-making under pressure – such as in first-person shooter (FPS) games – is still unclear: advantages in multitasking or general processing speed? To resolve this, we classified N = 230 players (16-34 years) of the video game Counter-Strike into four expertise clusters (Novice, Skilled, Emerging, Expert), assessing their processing speed and task-switching performance. To better understand the source of expertise effects, we used drift-diffusion modelling (DDM) to estimate non-decision and decision components of performance. Experts exhibited significantly faster reaction times than Novices, but no specific multitasking advantage was observed. The DDM revealed that this speed advantage was driven by higher drift rates and shorter non-decision times. No expertise-related differences were found in boundary separation, the strategic component of decision-making. Findings suggest that expert performance in decision-making under pressure is characterised by advantages in general processing speed rather than being associated with greater multitasking capabilities.
