Processing speed, not multitasking, drives expert decision-making under pressure.

= 230 players (16-34 years) of the video game Counter-Strike into four expertise clusters (Novice, Skilled, Emerging, and Expert), assessing their processing speed and task-switching performance. To better understand the source of expertise effects, we used drift-diffusion modeling to estimate nondecision and decision components of performance. Experts exhibited significantly faster reaction times than Novices, but no specific multitasking advantage was observed. The drift-diffusion modeling revealed that this speed advantage was driven by higher drift rates and shorter nondecision 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 characterized by advantages in general processing speed rather than being associated with greater multitasking capabilities. (PsycInfo Database Record (c) 2026 APA, all rights reserved).