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Referee vision and offside, 67 studies: an illusion explains some errors, decisions can be trained on screen, the effect in matches is yet to be measured.
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In brief. Across 67 studies of referees and judges, part of the offside errors comes from a perceptual illusion, experts stand out mainly through the accuracy of their decisions, and video training improves the decision measured off the field. One trial has no effect; no trial cited here measures the effect in matches. Updated on November 3, 2026.
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The midfielder winds up a through ball. Along the touchline, the assistant moves in side steps, level with the second-to-last defender who is stepping up. At the same moment, the striker sets off in the opposite direction. At the instant the foot touches the ball, the assistant must know which of the two was closer to the goal, then decide whether to raise the flag. At the 2002 World Cup, of 337 offside calls analyzed on video across the 64 matches, 26.2% of the decisions were wrong, and 86.6% of those errors were flags raised wrongly (Helsen et al., 2006).
An error that leans this much to one side points toward perception rather than chance. Refereeing also offers research a rare field: performance there is a filmed decision, verifiable frame by frame, where you can measure what perceptual training changes. The 67 studies gathered here answer in two steps: the decision improves on screen, and none yet shows that it improves in matches.
The first explanation was about viewing angle: a badly positioned assistant would see the players in perspective and misjudge the line (Oudejans et al., 2000). Reanalyzing these data, Baldo's team read something else in them, the flash-lag effect: a moving object is perceived ahead of its real position at the instant marked by a brief signal (Baldo et al., 2002). Here, the signal is the pass; the object, the striker setting off. In 2002, the assistant's position did not differ between right and wrong decisions (0.81 and 0.77 m ahead of the line), which the viewing-angle hypothesis did not predict (Helsen et al., 2006).
Assistants fix their gaze on the offside line before, during and after the pass, with no difference in gaze by level (Catteeuw et al., 2009). International assistants do not perceive better than amateur footballers; they shift their decision criterion toward abstention, at the price of more missed offsides (Put et al., 2013). In the Premier League, where the instruction was to give the benefit of the doubt to the attacker, the error flipped: 773 unflagged offsides against 95 wrongly raised flags across 4,960 situations (Catteeuw et al., 2010).
Study | Population (n) | What was done | Measure | Result | Transfer to the field | Level of evidence |
|---|---|---|---|---|---|---|
Not described in an abstract (letter to Nature, described from Baldo 2002 and Helsen 2006) | Analysis of offside errors | Link between viewing angle and error | Errors attributed to the viewing angle (optical hypothesis) | Not specified | Low | |
Data from Oudejans 2000 | Reanalysis | Type of error | The flash-lag effect contributes to wrongly raised flags | Match situations | Low | |
None, theoretical analysis | Calculation of the visual demands of offside | No measurement | The eye and brain could not analyze all the necessary information | Not measured | Very low | |
337 offsides, 64 matches of the 2002 World Cup | Video analysis | Errors, period, assistant's position | 26.2% errors, 86.6% wrongly raised flags, 38.5% errors in the first quarter hour; position without effect | Official match, observation | Moderate | |
29 FIFA assistants, 28 elite Belgians | 64 situations on a computer | Accuracy, remembered position | 76.4% versus 67.5%; striker remembered ahead (11.0 versus 8.4 pixels) | Not measured | Low to moderate | |
FIFA and Belgian assistants (sample size not given in the abstract) | Situations on the field, in animation and in video | Type of error | More wrongly raised flags on the field and in three-versus-three animation, and when the defender runs in the opposite direction to the striker | Training ground | Low | |
International and national assistants (sample size not given in the abstract) | Video simulations, eye tracker | Errors, gaze | Flag bias among nationals; line fixated before, during and after the pass; gaze with no difference between levels | Not measured | Low | |
4,960 league situations | Video analysis | Errors, criterion, fatigue, speed, angle | 17.5% errors, 773 unflagged against 95 wrongly raised flags; fatigue, speed and angle without effect | Official match, observation | Moderate | |
2002 and 2006 World Cups | Video analysis | Wrongly raised flags | 26.1% of flags wrongly raised in 2002 (58 out of 222), 10.0% in 2006 (24 out of 240); position without effect | Official match, observation | Moderate | |
380 fouls and 165 offsides, 2009 Confederations Cup | Video analysis | Errors, distance, angle, period | 13% errors by assistants; an angle of 46 to 60° safer; twice as many errors in the second half; distance to the line without effect | Official match, observation | Moderate | |
International assistants versus amateur footballers | Laboratory decision task | Sensitivity, criterion | Same sensitivity; criterion shifted toward abstention, more missed offsides | Not measured | Low to moderate | |
33 assistants | 40 situations in 2D and 3D | Accuracy | 80% in 3D versus 75% in 2D; image recognition without difference | Not measured | Low | |
One Bundesliga season; 10 assistants tested in the laboratory | Coordinates of the players and of the assistant | Visual angle, errors | Fewer errors when the assistant is farther away, the visual angle to cover being smaller | Official match, observation | Moderate | |
24 professional assistants | Offside task and attention task | Breadth of attention | Better attention on the horizontal axis, fewer errors | Not measured | Low | |
10 amateur assistants | 24 offsides at normal speed, x2 and x3, eye tracker | Accuracy, gaze | Comparable gaze; normal speed more accurate than x3, more misses at x3 | Not measured | Low | |
None, vision analysis applied to video assistance | Theoretical analysis | Spatial and temporal resolution | Contact judged 10 ms too late on average at 50 Hz; positions shifted by several centimeters | Video refereeing | Low | |
Three studies, one observational and two experimental | Number of players near the situation | Correct decisions | Added players lower accuracy, even when placed far from the line (visual clutter) | One observational study | Low to moderate | |
20 non-expert assistants | Offside in video, eye tracker | Gaze, estimated quiet eye | Gaze mostly on the ball carrier; entropy above 90%; quiet eye unrelated to accuracy | Not measured | Low | |
26 assistants, experts versus novices | 100 images from the 2014 World Cup, eye tracker and evoked potentials | Accuracy, gaze, brain activity | 0.79 versus 0.71; fewer, shorter fixations (220.59 versus 340.61 ms); preliminary evoked potentials | Not measured | Low |
In Wu's meta-analysis, expert officials decide more accurately than the others (SMD = 1.09) and make fewer fixations (SMD = 0.71), with no difference in fixation duration (Wu et al., 2024). Ziv's review of twelve studies of referees' gaze finds seven differences between levels and four absences of difference. Its authors urge caution before adopting gaze training, because the data on its effectiveness are, in their view, scarce and sometimes contradictory (Ziv et al., 2020).
Recent studies go in the same direction. Among 51 handball referees, decision accuracy separates the levels while fixations and saccades do not differ (Świdwa et al., 2025). In basketball, experts decide better with as many fixations, of the same duration, but distributed differently between areas of the court (Wang et al., 2025). When a gaze difference exists, it concerns where and when: the contact zone among elite Belgian referees (Spitz et al., 2016), an anchor point on the stumps among cricket umpires (Ramachandran et al., 2021), an earlier and longer quiet eye in softball (Millslagle et al., 2013). Scanning in football raises the same question on the player's side.
Among judges, knowing how to perform the movement is not enough: in gymnastics, those who could perform the vault look almost like high-level judges, without scoring better (Pizzera et al., 2018). And expertise has its limits: in rhythmic gymnastics, the best international judges detect only about 40% of the actual faults (Flessas et al., 2015).
Study | Population (n) | What was done | Measure | Result | Transfer to the field | Level of evidence |
|---|---|---|---|---|---|---|
39 referees, 20 elite and 19 of lower level | 20 foul clips, eye tracker | Accuracy, gaze | Disciplinary accuracy in open play 61.0% versus 45.3%; more time on the contact zone (1.33 versus 1.19 s) | Not measured | Low | |
15 national referees, 15 of lower level | 30 foul clips, eye tracker | Accuracy, time, gaze | Accuracy without difference; national referees faster in contests for the ball; earlier fixation on the offender's upper body (d = 0.87) | Not measured | Low | |
4 elite referees, 12 of lower level | Real match refereed with a mobile eye tracker, 196 long passes | Fixations, anticipation | 1.3 versus 1.8 fixations per second; ball fixated at the kick 77% versus 52%; earlier anticipation | In match | Low | |
4 elite referees, 8 of lower level, in situation | Head and eye movements in match | Exploration movements | About 75% of movements carried by the head; elites faster; exploration avoided during passes | In match | Low | |
9 elite referees, 9 trainees, 9 players | 10 scrums in video, eye tracker | Accuracy, gaze | Referees more accurate, exploration slower, more centered on the pack; exploration speed unrelated to accuracy | Not measured | Low | |
51 handball referees, 31 high-level and 20 of lower level | Video situations, eye tracker | Decision, sanctions, gaze | High level more accurate (d = 0.68; 1.41 for sanctions); gaze without significant difference by level and sex | Not measured | Low | |
8 experienced basketball referees, 8 less experienced | Real matches, eye tracker | Fixations | Total fixation time shorter among the experienced; in the trail position, more and shorter fixations | In match | Low | |
10 expert basketball referees, 10 novices | 20 video clips, eye tracker | Accuracy, gaze | Higher accuracy; number, duration and entropy of fixations without difference; fixation time distributed differently between zones | Not measured | Low | |
19 studies retained out of 1,706, basketball | Systematic review | Uses of eye tracking | Less experienced referees overlook key cues | Variable | Review | |
12 expert cricket umpires, 19 novices | Leg-before-wicket decisions, eye tracker | Accuracy, gaze | Experts more accurate; last fixation anchored on the stumps | Not measured | Low | |
4 cricket umpires, simulated match | Three ways of watching the bowler's foot | Decision accuracy | Better accuracy without watching the foot than when watching the front foot | Simulated match | Very low | |
10 elite cricket umpires | Interviews | Strategies described | Use of a gaze anchor point | Match experience | Low, qualitative | |
4 expert umpires, 4 near-expert | Simulated pitches, mobile eye tracker | Quiet eye | Earlier onset (50.0% versus 56%), longer duration (15.1% versus 9.3%) | Simulated situation | Very low | |
4 expert umpires, 4 near-expert | Simulated pitches, mobile eye tracker | Quiet eye | Earlier and longer quiet eye among experts | Simulated situation | Very low | |
14 expert fencing referees, 14 novices | Video situations, eye tracker | Accuracy, gaze | Experts more accurate, fewer and longer fixations | Not measured | Low | |
8 players, 8 coaches, 8 beach volleyball referees, 8 controls | Attacks in video cut off at three moments | Anticipation | Players and coaches better than referees at the latest cut-off | Not measured | Low | |
10 expert gymnastics judges, 10 novices | Observation in real competition | Gaze | Novices look less at the gymnast and more at the score sheet | In competition | Low | |
30 rhythmic gymnastics judges, 10 per level | Simulated scoring, eye tracker | Faults detected, gaze | About 40% of actual faults detected by the best; only national judges make use of their fixations | Not measured | Low | |
35 gymnastics judges | 21 vaults in video, eye tracker | Accuracy, gaze | Higher license level, better score and more fixations on the head and arms; motor experience without better judging | Not measured | Low | |
14 visual experts, 17 motor experts, 18 novices | Floor routine in video and as a figurine | Score, accuracy, gaze | Groups differ in score (ηp² = 0.242) and accuracy (ηp² = 0.196), not in gaze | Not measured | Low | |
Judges and skaters | Evaluation of skating jumps, eye tracker | Area looked at | Judges look at the lower limbs, skaters at the face | Not measured | Low | |
6 expert artistic swimming judges, 7 novices | Figures in video, eye tracker, pupil | Gaze, score | Experts more fixated on the upper limbs, higher scores | Not measured | Very low, exploratory | |
25 boxing officials, 20 judges and 5 supervisors | Classic ropes versus transparent ropes | Scores by ring zone | With classic ropes, one judge departs from the reference in zone D; transparent ropes, higher and more consistent scores (d from 0.36 to 0.50) | In competition | Low | |
12 studies | Review | Gaze by level | 7 studies with a difference, 4 without | Few studies in ecological conditions | Review | |
Studies published up to the end of 2022 | Meta-analysis | Accuracy, fixations | Accuracy SMD = 1.09; number of fixations SMD = 0.71; duration SMD = 0.23, not significant | Not measured | Moderate |
Among 71 Portuguese officials, 92% of the national elite, the vision measured in 44 of them resembles the norms and does not differ by level (Baptista et al., 2017). In a second sample, depth perception and visual memory explain 22% of the variance in the ranking of 59 officials (Baptista et al., 2021).
On fatigue, studies diverge. At Euro 2000, central referees ran at an average of 85% of their maximum heart rate and made 137 observable decisions per match (Helsen and Bultynck, 2004). In 2009, offside errors doubled in the second half (Mallo et al., 2012), whereas in the Premier League fatigue had no effect (Catteeuw et al., 2010) and in 2002 the error peak fell in the first quarter hour (Helsen et al., 2006).
Study | Population (n) | What was done | Measure | Result | Transfer to the field | Level of evidence |
|---|---|---|---|---|---|---|
60 basketball referees | Visual screening | Acuity, ocular motility, accommodation, vergence | Very high-level vision | Not measured | Very low | |
Euro 2000 referees, 31 matches | Match analysis | Physical load, decisions | 85% and 77% of maximum heart rate; 137 decisions per match (104 to 162), 64% via communication | Official match, observation | Moderate | |
41 referees aged 31 to 42 | 10 best versus 10 worst decision makers in video | Visual skills | The best have better visual skills (memory, reaction, periphery, saccades, accommodation) | Not measured | Low | |
71 Portuguese officials, 22 referees and 49 assistants | Clinical visual examination (44 subjects) and questionnaire | Visual functions | Vision comparable to norms, with no difference by level; 18.3% never examined or not for more than 3 years; about a quarter would see better with correction | Not measured | Low | |
59 officials, 21 referees and 38 assistants | Clinical and perceptual measures | Link with ranking | Depth perception and visual memory explain 22% of the variance in ranking | Official ranking | Low | |
159 officials | Visual screening | Visual functions | 1.88% color vision deficit; 3.14% to be rechecked | Not measured | Very low | |
33 referees, 20 assistants | Attention test after the FIFA physical test | Visual attention | 44% of the 34 who pass both tests decline afterward; increased reaction variability | Not measured | Low | |
61 referees | Perception speed and attention tests | End-of-season ratings | Perception speed predicts ratings, all the more so when attentional control is good | Official ratings | Low | |
Referees and assistants (sample size not given in the abstract) | Line bisection | Leftward attention bias | The bias decreases with months of experience among referees, not among assistants | Not measured | Low | |
American football officiating | Perspective article | Dynamic acuity, vestibulo-ocular reflex, visual field | Proposal of virtual reality training | Not measured | Opinion | |
American football officiating | Narrative review | Image slip on the retina | Mechanisms and countermeasures proposed, standardized curriculum | Not measured | Opinion |
The offside decision can be trained off the field. An off-field program improves assistants' accuracy without changing their gaze or their memory of positions (Catteeuw et al., 2010a). With feedback after each situation, video and animation give the same gains and reduce wrongly raised flags (Catteeuw et al., 2010b). For fouls, blurred video makes experienced referees more sensitive to real fouls (van Biemen et al., 2018). Among 52 Australian football referees, twelve weeks of video mainly improve the less experienced, with retention at three weeks (Larkin et al., 2018).
One trial is the exception. Twenty amateur Australian football referees are randomly split into three groups for eight weeks: physical conditioning alone, physical conditioning with an integrated video task, physical conditioning and video kept separate. Decision changes remain uncertain between the groups, and video adds nothing, whether integrated or not (Kittel et al., 2019). The authors recommend adding detailed feedback, like the kind that one of the Leuven programs gave after each situation (Catteeuw et al., 2010b).
In meta-analysis, across 6 randomized trials and 163 football referees, g = 1.718 (Zhou et al., 2025). Across 14 studies of team-sport officials, g = 0.68, with 1.48 for an objective decision such as offside, weaker effects for decisions that require interpretation, and programs of 4 to 6 weeks in the lead (Kittel et al., 2025). These gains are measured on tests close to the training: the question of near and far transfer remains open.
Study | Population (n) | What was done | Measure | Result | Transfer to the field | Level of evidence |
|---|---|---|---|---|---|---|
Elite assistants (sample size not given in the abstract) | Off-field offside program | Accuracy, memory of positions, gaze | Accuracy improved; memory and gaze unchanged | Not measured | Low | |
Assistants (sample size not given in the abstract) | Video versus animation, feedback after each situation | Accuracy, wrongly raised flags | Progress in both groups, fewer wrongly raised flags; format without effect, video judged more faithful | Not measured | Low to moderate | |
10 trained assistants, 10 controls | 12 online sessions | Image recognition, decision | Recognition then decision improved | Not measured | Low to moderate | |
Two groups of experienced referees (sample size not given in the abstract) | Ambiguous fouls in blurred versus normal video | Accuracy, sensitivity, bias | Accuracy improved through better sensitivity to real fouls, with no effect on bias or time | Not measured | Low to moderate | |
52 Australian football referees, randomized | 12 weeks of video without explicit instruction | Decision, retention at 1 and 3 weeks | Group x test interaction (ηp² = 0.074); less experienced ηp² = 0.201 | Not measured | Moderate | |
20 amateur Australian football referees (7, 7 and 6) | 8 weeks: interval conditioning alone, video integrated into the intervals, video separate | Yo-Yo IR1, 10 x 300 m with video task | Uncertain decision changes; no added benefit from video | Not measured | Low to moderate, trial with no effect | |
Amateur Australian football referees, three groups | 5 weeks of video at 100% or 150% speed, or nothing | Decision at rest and during exertion | Only the real-speed group improves, only during exertion (p = 0.043) | Not measured | Low | |
6 randomized trials, 163 football referees | Meta-analysis | Decision | g = 1.718 (95% CI 1.058 to 2.377); small samples | Not measured | Moderate | |
14 studies of team-sport officials | Meta-analysis | Decision | g = 0.68; football 1.05, rugby 0.90, Australian football 0.24; offside 1.48; 4 to 6 weeks more effective | Transfer to the match to be evaluated, according to the authors | Moderate |
A 360-degree video test can be reliable and can separate elite referees from amateurs (Kittel et al., 2019). Yet among 21 elite referees followed over four matches, neither this test nor a test on broadcast footage distinguishes the best decision makers in match (Kittel et al., 2021). The authors see a problem of representativeness, in the sense of representative design: the off-field task must keep the constraints of the field.
The van Biemen team checked this on the gaze side. Lower-level referees behave in virtual reality as they do on the field, and quite differently in front of a video (van Biemen et al., 2023). On a screen, the referee does not move, does not turn the head and does not choose the angle; the perception-action coupling they exercise in a match disappears. Our article on virtual reality and decision-making compares these tools.
Study | Population (n) | What was done | Measure | Result | Transfer to the field | Level of evidence |
|---|---|---|---|---|---|---|
13 elite referees, 15 amateurs of Australian football | Two tests of 60 clips, in 360 video and in broadcast footage | Reliability, discrimination | ICC = 0.89 for both tests; elites better; 360 video judged closer to the game | Not measured | Low | |
21 elite referees, 4 matches each | Two tests of 25 clips compared with the decision in match | Link between test and match | No test separates the best decision makers in match; only the unjustified decisions of the broadcast test agree | Measured, link absent | Low to moderate | |
Lower-level referees | Decisions in match, in virtual reality and in video | Decision, gaze, head movements | Behavior in virtual reality indistinguishable from the field; in video, clearly different | Measured for gaze | Low to moderate |
Study A | Relationship | Study B |
|---|---|---|
Oudejans 2000 (viewing angle) | reinterpreted by | Baldo 2002 (flash-lag effect), then Helsen 2006 (position without effect) |
Helsen 2006 and Catteeuw 2010, Premier League (angle and position without effect) | contradicted on angle by | Mallo 2012 (angle of 46 to 60° safer) and Hüttermann 2017 (favorable distance) |
Mallo 2012 (errors doubled in the second half) | contradicts | Helsen 2006 (peak in the first quarter hour) and Catteeuw 2010, Premier League (fatigue without effect) |
Put 2013 (criterion shifted toward abstention) | sheds light on | the drop in wrongly raised flags between 2002 and 2006 (26.1% then 10.0% of flags raised) and the rise in missed offsides in the Premier League, which Catteeuw 2010 attributes to the instructions given to assistants |
Catteeuw 2010b (feedback after each situation, progress) | sheds light on | Kittel 2019 (no benefit; the authors recommend adding detailed feedback) |
Zhou 2025 (g = 1.718, football alone) | finds a higher effect than | Kittel 2025 (g = 0.68 for all team sports, 1.05 for football); Kittel, Larkin and Spittle, authors of the Australian trials cited here, co-sign this meta-analysis |
Kittel 2019, validation (reliable test) | does not guarantee | Kittel 2021 (no link with the match) |
Wu 2024 (fewer fixations among experts) | qualified by | Świdwa 2025 and Mack 2020 (gaze without difference, decision different), Wang 2025 (as many fixations, distributed differently) |
Pizzera 2018 (motor experience without better judging) | complements | Cañal-Bruland 2011 (players anticipate better than referees): knowing how to perform the movement helps to predict, not necessarily to score |
Caveat: a large share of the offside studies comes from the same Leuven team (KU Leuven), around Werner Helsen, who also co-signs Ziv's review. This work reads as a coherent series rather than as independent replications; teams from Madrid (Mallo 2012), Cologne (Hüttermann 2017, Noël 2021) and Amsterdam (van Biemen) bring outside data.
Established, through match and laboratory analyses: wrongly raised flags follow the logic of the flash-lag effect, and expert assistants compensate through their decision criterion more than through their perception. Also established, through meta-analysis: experts decide more accurately (Wu et al., 2024), and video training improves the decision measured off the field (Zhou et al., 2025; Kittel et al., 2025). Debated: the existence of an expert gaze, the effect of fatigue and of angle, the size of the gains (g from 0.68 to 1.72), their duration, measured at best three weeks later. Extrapolation: that these gains carry over to an official match, or that training visual functions makes a better referee. Nobody can promise you that an assistant trained in front of a screen will raise fewer flags wrongly on Saturday.
This hypothesis can be tested. Take a randomized trial over a season: assistants of the same level follow either a video offside program with feedback after each situation, or their usual preparation, and video analysis counts the wrongly raised flags and missed offsides in official matches. If the total number of errors does not drop among the trained assistants, or if every wrongly raised flag avoided is paid for with a missed offside, the transfer from screen to match no longer holds.
Among 71 high-level officials, 18.3% had never had an eye exam or not for more than three years, and the measurements made on 44 of them suggest that about a quarter might see better with an appropriate correction (Baptista et al., 2017). If you coach referees and one of them reports double vision, a blur that persists, headaches during exertion or dizziness, visual training waits. They first see an ophthalmologist, then an orthoptist in France, or an optometrist in Switzerland or the United States. LabO RNP is neither medical nor paramedical, and comes in addition to a care pathway, never in its place. LabO RNP works with optometrists; the curriculum was built with them.
In a match, the referee explores mostly with the head: among the 12 referees followed, about three quarters of the exploration movements go through it (Van Biemen and Mann, 2024). During running and these rotations, the vestibulo-ocular reflex stabilizes the gaze on its target, a point that two articles on American football officiating highlight (Ong et al., 2024; Panzo et al., 2025). LabO RNP trains movement professionals in the sensory aspects of movement and in the entire sensorimotor loop, and the referee offers a complete example: positioning, turning the head, perceiving, then deciding. The oculomotor exercises in the warm-up and the map of the evidence in sports vision extend this article.
Part of the errors comes from the flash-lag effect, which makes the moving striker be perceived ahead of his position at the moment of the pass: at the 2002 World Cup, 86.6% of the errors were wrongly raised flags (Helsen et al., 2006). The presence of additional players near the action also degrades the decision (Noël and Klatt, 2021).
On screen, yes: two meta-analyses find clear gains, stronger for offside than for fouls requiring interpretation (Zhou et al., 2025; Kittel et al., 2025). One eight-week trial showed no benefit, and its authors recommend adding detailed feedback (Kittel et al., 2019). The effect in official matches has not been measured.
Sometimes. One meta-analysis finds fewer fixations among experts (Wu et al., 2024), but other studies find no gaze difference while the decision differs, among handball referees (Świdwa et al., 2025) as among gymnastics judges (Mack, 2020). Accuracy separates the levels more reliably than gaze.
Results diverge. Offside errors double in the second half at the 2009 Confederations Cup (Mallo et al., 2012), but fatigue has no effect in the Premier League (Catteeuw et al., 2010). Right after the FIFA physical test, 44% of the officials who had passed this test and a first attention test do worse on the second (Schmidt et al., 2019).
Yes: nearly one high-level official in five had never been examined, or not for more than three years (Baptista et al., 2017). Ophthalmologist first, then orthoptist in France or optometrist in Switzerland and the United States. LabO RNP is neither medical nor paramedical, and comes in addition to a care pathway, never in its place.
The best assistants have mostly learned to doubt at the right moment, and that is the decision that can be trained.
👉 I want to understand how what an athlete perceives becomes a decision.
By the LabO RNP team
Method. On November 3, 2026, 76 lines of the consolidated LabO RNP inventory on athlete vision matched the refereeing keywords (referee, assistant, judge, offside). 14 are set aside: 10 do not concern officials, one concerns participants not identified as referees, one has neither PMID nor abstract, one describes a general medical profile, one is a general review. 5 studies are added via PubMed (Oudejans 2000, Gilis 2008 and 2009, Zhou 2025, Kittel 2025), making 67 analyzed. PMID and DOI verified on PubMed on November 3, 2026.
Adie JM, Renshaw I, Russell S, Polman R, Mann DL (2024). That's out! How expert umpires make leg-before-wicket judgements in cricket. J Sports Sci, 42(5), 455-464. PMID 38630902. doi:10.1080/02640414.2024.2338024
Albaladejo-García C, Luis-Del Campo V, Morenas J, Moreno FJ (2024). Gaze Behaviors, Estimated Quiet Eye Characteristics, and Decision Making of Nonexpert Assistant Referees Judging Offside Events in Soccer. J Sport Exerc Psychol, 46(5), 283-292. PMID 39245442. doi:10.1123/jsep.2023-0348
Alemanno M, Di Pompeo I, Marcaccio M, Canini D, Curcio G, Migliore S (2025). From Gaze to Game: A Systematic Review of Eye-Tracking Applications in Basketball. Brain Sci, 15(4). PMID 40309899. doi:10.3390/brainsci15040421
Babadi Aghakhanpour N, Abdoli B, Farsi A, Moeinirad S (2021). Comparison of Visual Search Behavior and Decision-making Accuracy in Expert and Novice Fencing Referees. Optom Vis Sci, 98(7), 783-788. PMID 34310548. doi:10.1097/OPX.0000000000001726
Baldo MV, Ranvaud RD, Morya E (2002). Flag errors in soccer games: the flash-lag effect brought to real life. Perception, 31(10), 1205-10. PMID 12430947. doi:10.1068/p3422
Baptista AMG, Serra PM, McAlinden C, Barrett BT (2017). Vision in high-level football officials. PLoS One, 12(11), e0188463. PMID 29161310. doi:10.1371/journal.pone.0188463
Baptista AMG, Serra PM, Faisal M, Barrett BT (2021). Association between Clinical Vision Measures and Visual Perception and Soccer Referees' On-field Performance. Optom Vis Sci, 98(7), 789-801. PMID 34328457. doi:10.1097/OPX.0000000000001722
Behesht Nejad AH, Seif Barghi T, Hassanmirzaei B, Ghanbari L, Naderifar H (2021). Evaluation of Visual Skills in Soccer Referees and Assistant Referees. Med J Islam Repub Iran, 35, 169. PMID 35505830. doi:10.47176/mjiri.35.169
Belda Maruenda F (2004). Can the human eye detect an offside position during a football match?. BMJ, 329(7480), 1470-2. PMID 15604187. doi:10.1136/bmj.329.7480.1470
Bruno N, D'Amico P, Uccelli S (2026). Lateralization of spatial attention: Evidence from line bisections by football officials. Laterality, 31(6), 703-714. PMID 42503990. doi:10.1080/1357650X.2026.2709757
Cañal-Bruland R, Mooren M, Savelsbergh GJ (2011). Differentiating experts' anticipatory skills in beach volleyball. Res Q Exerc Sport, 82(4), 667-74. PMID 22276408. doi:10.1080/02701367.2011.10599803
Catteeuw P, Helsen W, Gilis B, Van Roie E, Wagemans J (2009). Visual scan patterns and decision-making skills of expert assistant referees in offside situations. J Sport Exerc Psychol, 31(6), 786-97. PMID 20384013. doi:10.1123/jsep.31.6.786
Catteeuw P, Gilis B, Wagemans J, Helsen W (2010). Perceptual-cognitive skills in offside decision making: expertise and training effects. J Sport Exerc Psychol, 32(6), 828-44. PMID 21282840. doi:10.1123/jsep.32.6.828
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