Cognitive processing characteristics of the advantage of assistant referee offside decision-making: evidence from eye...

Offside decision-making in football is prone to misjudgments that significantly affect match outcomes. Although video assistant referee (VAR) technology has been introduced, it may cause game interruptions and is subject to technical limitations; thus, improving assistant referees' on-field judgment is crucial. Previous studies have focused on behavioral differences in refereeing decisions, but the cognitive processing characteristics and neural mechanisms underlying the decision-making advantage of expert assistant referees remain unclear.

A total of 26 assistant referees were divided into an expert group (level 1 and above, with over 6 years of experience) and a novice group (level 3 and below). A mixed 2 × 2 factorial design (referee level: expert/novice; stimulus type: offside/non-offside images) was used. The stimuli were derived from 2014 World Cup match footage, comprising 25 offside and 75 non-offside images. Eye-tracking technology and a 64-channel event-related potential (ERP) system were used to record behavioral indicators (reaction time and accuracy), eye-movement indicators (number of fixation points, average fixation duration, and gaze trajectory), and ERP components (N2, P300, late slow wave, and PSW) during the decision-making process. Data were analyzed using repeated-measures ANOVA.

(1) Behavioral data: Expert referees responded faster than novices. In offside images, their RT was 2,408.92 ± 276.03 ms. Their accuracy was also higher (0.79 ± 0.10 vs. 0.71 ± 0.13). (2) Eye movement data: Experts made fewer fixations within the region of interest than novices (5.62 ± 1.36 vs. 7.05 ± 1.78). Their average fixation duration was also shorter (220.59 ± 45.69 ms vs. 340.61 ± 118.03 ms). Their attention was primarily focused on the offside line. (3) ERP data: The ERP results were preliminary. Experts showed shorter N2/P300 latencies and lower P300 amplitude. This may indicate faster stimulus evaluation and less additional allocation of cognitive resources. These results should be interpreted cautiously because participant-level artifact-free trial counts could not be reconstructed.

Expert assistant referees showed an advantage in offside decisions. This advantage may be related to a refined visuospatial working memory system. This system enables them to deploy attention quickly, search for key visual cues, and process information efficiently. Behavioral and eye-movement results, together with preliminary ERP evidence, support this interpretation. The findings may provide theoretical support for referee training programs. However, the ERP results should be treated as preliminary because artifact-free trial counts could not be reconstructed.