Due to the COVID-19 pandemic, European elite football (a.k.a. soccer) leagues played the remaining season 2019/20 without or strongly limited attendance of supporters (i.e., “ghost games”). From a sport psychological perspective this situation poses a unique opportunity to investigate the crowd's influence on referee decisions and the associated effect of “home advantage.” A total of 1286 matches–played in the top leagues of Spain, England, Germany, Italy, Russia, Turkey, Austria and the Czech Republic–were analyzed for results, fouls, bookings and reasons for bookings and contrasted between respective matchdays of season 2018/19 (regular attendance) and season 2019/20 (ghost games). Following recent methodological developments in the research on the home advantage effect, four different statistical analyses–including Pollard's traditional method–were used for the assessment of the home advantage effect. There are two main findings. First, home teams were booked significantly more often with yellow cards for committing fouls in ghost games. Most importantly, this effect was independent of the course of the games. In contrast, bookings for other reasons (criticism and unfair sportsmanship) changed similarly for both home and away teams in ghost games. Second, the overall home performance and home advantage effect in the respective elite leagues–identified in the respective matches of the regular 2018/19 season–vanished in the ghost games of the 2019/20 season. We conclude that the lack of supporters in top European football during the COVID-19 pandemic led to decreased social pressure from the ranks on referees, which also had a potential impact on the home advantage. Referees assessed the play of home teams more objectively, leading to increased yellow cards awarded for fouls committed by the home teams. Since there were no significant changes in referee decisions against the away teams, we argue that our observations reflect a reduction of unconscious favoritism of referees for the home teams.

ObjectiveSeveral studies report evidence for training-related neuroplasticity in the visual cortex, while other studies suggest that improvements simply reflect inadequate eye fixation control during perimetric prediagnostics and postdiagnostics.Methods and analysisTo improve diagnostics, a new eye-tracking-based methodology for visual field analysis (eye-tracking-based visual field analysis (EFA)) was developed. The EFA is based on static automated perimetry and additionally takes individual eye movements in real time into account and compensates for them. In the present study, an evaluation of the EFA with the help of blind spots of 58 healthy participants and the individual visual field defects of 23 clinical patients is provided. With the help of the EFA, optical coherence tomography, Goldmann perimetry and a Humphrey field analyser, these natural and acquired scotomas were diagnosed and the results were compared accordingly.ResultsThe EFA provides a SE of measurement of 0.38° for the right eye (OD) and 0.50° for the left eye (OS), leading to 0.44° of visual angle for both eyes (OU). Based on participants’ individual results, the EFA provides disattenuated correlation (validity) of 1.00 for both OD and OS. Results from patients suffering from cortical lesions and glaucoma further indicate that the EFA is capable of diagnosing acquired scotoma validly and is applicable for clinical use.ConclusionOutcomes indicate that the EFA is highly reliable and precise in diagnosing individual shape and location of scotoma and capable of recording changes of visual field defects (after intervention) with unprecedented precision. Test duration is comparable to established instruments and due to the high customisability of the EFA, assessment duration can be shortened by adapting the diagnostic procedure to the patients’ individual visual field characteristics. Therefore, the saccade-compensating methodology enables researchers and healthcare professionals to rule out eye movements as a source of inaccuracies in pre-, post-, and follow-up assessments.

The phenomenon of home advantage (home bias) is well-analyzed in the scientific literature. But only the COVID-19 pandemic enabled studies on this phenomenon—for the first time in history—on a global scale. Thus, several studies to date examined the effects of empty stadiums by comparing regular matches (with supporters) before the COVID-19 restrictions with so-called ghost games (games without supporters) during the pandemic. To synthesize the existing knowledge and offer an overview regarding the effects of ghost games on home advantage we provide a systematic literature review on this topic. Our findings—based on 26 primary studies—indicate that ghost games have a considerable impact on the phenomenon of home advantage. Deeper analysis further indicates that this effect is based on a reduced “referee bias” and a lack of “emotional support from the ranks”. From a psychological perspective, we argue that our conclusions are highly relevant by emphasizing decision making under pressure and crowd-induced motivation in sports. From a socio-economic perspective, we argue that our findings legitimize a discussion regarding compensation of fans after sporting success as plausible and worth considering. Thus, our results are significant for scientists, sports and team managers, media executives, fan representatives and other persons responsible in the football industry.

During the COVID-19 pandemic the “Austrian Bundesliga”—as in many other European football leagues—resumed the season around the end of May 2020 without supporters in the stadiums. These so-called “ghost games” represent a unique and unprecedented opportunity to study the effects of the (missing) audience on the behavior and experience of sports professionals. The present study is the first of its kind, aimed at addressing the psychological effects of these “ghost games” on football players, staff, and officials. The newly developed “Analysis System for Emotional Behavior in Football” (ASEB-F) was used to video analyze and compare the behavior of players, staff, and officials in—in sum—20 games of FC Red Bull Salzburg in the “Championship Groups” of season 2018/19 (“regular games”) and season 2019/20 (“ghost games”). Additionally, the two seasons were compared based on official matchday statistics. Overall, there were 19.5% fewer emotional situations in “ghost games” than in “regular games”. The results further show a relative increase in the number of emotional behaviors “Self-Adaptor” (+0.8%), “Protest” (+4.2%), and “Fair-Play-Behavior” (+3.1%) in “ghost games”, whereas “Words fight” (−5.1%) and “Discussion” (−5.1%) decreased in “ghost games”. In “regular games” referees were actively involved in 39.4% of all documented emotional situations, whereas in “ghost games” referees were actively involved in only 25.2% of all documented emotional situations (−14.2%). Chronological analysis within games—from kick-on to kick-off—further shows substantial differences in the temporal occurrence of emotional behavior between “regular games” and “ghost games”. The study provides unprecedented insights into the effects of missing supporters in the football games during the COVID-19 pandemic on emotional behavior on the pitch. Without the external factor of supporters, players and staff acted more factually and got less carried away with longer-lasting and extensive “Words fights” and “Discussion”. The evidence from this study indicates that—from a sport psychological perspective—the absence of supporters has a substantial influence on the experience and behavior of players, staff, and officials alike.

Humans grossly underestimate exponential growth, but are at the same time overconfident in their (poor) judgement. The so-called ‘exponential growth bias' is of new relevance in the context of COVID-19, because it explains why humans have fundamental difficulties to grasp the magnitude of a spreading epidemic. Here, we addressed the question, whether logarithmic scaling and contextual framing of epidemiological data affect the anticipation of exponential growth. Our findings show that underestimations were most pronounced when growth curves were linearly scaled and framed in the context of a more advanced epidemic progression. For logarithmic scaling, estimates were much more accurate, on target for growth rates around 31%, and not affected by contextual framing. We conclude that the logarithmic depiction is conducive for detecting exponential growth during an early phase as well as resurgences of exponential growth.