Slow motion replays that will be in use during the World Cup make football referees harsher, according to new academic research.
The game’s governing body, FIFA, has officially approved the use of the controversial Video Assistant Referee (VAR) system in the World Cup which kicks off in Russia on Thursday.
But a new study suggests that football referees penalise situations more severely when watching them in slow motion compared to real time.
Under the VAR system, four types of calls can be reviewed: goals and whether there was a foul during the build-up; penalty decisions; red card decisions, and mistaken identity in awarding a red or yellow card.
Researchers at Leuven University in Belgium studied the response of 88 elite football referees to video clips of a foul warranting a yellow card.
They found no significant difference in the accuracy of a referee’s decision about if a foul had occurred or not, with slow-motion videos (63 per cent accurate) compared to the real-time videos (61 per cent accurate).
But the judgement of intention or force behind a foul differed. More red cards were given by referees watching in slow motion compared to those watching real time video playbacks.
Study corresponding author Dr Jochim Spitz said: “Our results suggest that slow motion can increase the severity of a judgement of intention, making the difference between perceiving an action as careless (no card), reckless (yellow card) or with excessive force (red card).
“The finding that referees were more likely to make more severe decisions following slow motion replays, is an important consideration for developing guidelines for the implementation of VAR in football leagues worldwide.”
The researchers concluded that although slow motion playback could be a useful tool in assessing some decisions – such as off-side and determining the exact impact of a contact – it may not be the best tool for decisions that involve judging human behaviour and intention.
Dr Spitz said: “Slow motion video may make it clearer who initiated a foul, whether there actually was contact and whether a foul occurred either inside or outside the penalty area.
“However, judging human emotion, like intentionality is quite another story.
“It is also the reason why slow motion footage cannot be used anymore in the court room as it increases the perceived intent.”
To investigate the impact of viewing speeds on decisions made by referees, the researchers showed 88 elite football referees from five European countries 60 video clips of foul situations from football matches in real time or slow motion.
Two independent ex-international referees that are currently acting as refereeing experts determined the correct decisions as a point of reference and then the referees who took part in the study categorised the fouls as they would in a real match by awarding a yellow card, a red card or no card.
Dr Spitz added: “This is the first time that the impact of slow motion video on decision making has been studied in sports referees and it is timely given the current debate on VAR, which will be used in the World Cup.”
The findings were published in the journal Cognitive Research: Principles and Implications.