Monday, 12 May 2025
A new gambling study has found that payout information shown on slot machines is misleading and is making players believe they have a higher chance of winning.
Scientists from the University of Nottingham’s School of Psychology led a study involving over 6,000 slot machine players analysing the different regulatory messages shown on slot machines The commonly used ‘Return to Player’ message was found to almost universally increase perceived chances of winning when compared to no message at all. The findings have been published in the journal Addictive Behaviours.
Recent research suggests that as many as 1.3 million adults in Britain may be experiencing problem gambling (2.5% of the adult population). In addition, a significant number of people are considered at-risk or moderate-risk gamblers, with estimates ranging from 480,000 to 2.2 million. In 2023 the government published a white paper outlining a range of measures that could be taken by the gambling industry to provide more protection for gamblers via a range of regulatory measures, including improving the current approaches to presenting information on risk and return to player.
One measure already taken by gambling operators – as mandated by the UK’s Gambling Commission - is to disclose information about each gaming machine’s payout ratios. The operators can choose the type of messages they use. The “return-to-player” (RTP) is the most widely used and indicates the percentage of total money wagered that is anticipated to be returned to players over time, expressed as a percentage, for example, “This game has an average payout of 90%.”
There is also the ‘House Edge’ messaging that focuses on loss - “This game keeps 10% of all money bet” or, “This game is programmed to cost you 10% of your stake on each bet.
This study compared these two types of messaging against no information and showed slot players either the RTP message, two different House Edge (HE) messages or no information, and asked to rate their perceived chances of winning at a new slot machine.
The study showed that a typical 90% return-to-player message increased the perceived chances of winning at a new slot machine in comparison to no information at all. The House Edge messages were no better than having no information given, demonstrating that current messages are not effectively communicating the odds of winning or risk of losing.
The research was led by Dr Leonardo Cohen in the School of Psychology at the University of Nottingham
The RTP message is the preferred wording choice of most gambling operators and we wanted to find out if it works as a way of ensuring the player understands their chances. We know from previous research that the RTP messaging is almost universally misunderstood, with as many as half of gamblers thinking it means they have a 90% chance of winning, when actually their chances are significantly less.
Whilst the message in itself is factually accurate, it is ambiguous and as we found very open to misinterpretation, and in many cases had the opposite desired effect and made the machine seem more attractive to a player against ones that didn’t display any information or information focusing on losses instead of gains. This is evidence that the messaging needs to be much clearer, to ensure gamblers understand their chances of winning and so can make informed choices.
Story credits
More information is available from Dr Leonardo Cohen on Leonardo.Cohen@nottingham.ac.uk
Notes to editors:
About the University of Nottingham
Ranked 97 in the world and 17th in the UK by the QS World University Rankings, the University of Nottingham is a founding member of Russell Group of research-intensive universities. Studying at the University of Nottingham is a life-changing experience, and we pride ourselves on unlocking the potential of our students. We have a pioneering spirit, expressed in the vision of our founder Sir Jesse Boot, which has seen us lead the way in establishing campuses in China and Malaysia - part of a globally connected network of education, research and industrial engagement.
Nottingham was crowned Sports University of the Year by The Times and Sunday Times Good University Guide 2024 – the third time it has been given the honour since 2018 – and by the Daily Mail University Guide 2024.
The university is among the best universities in the UK for the strength of our research, positioned seventh for research power in the UK according to REF 2021. The birthplace of discoveries such as MRI and ibuprofen, our innovations transform lives and tackle global problems such as sustainable food supplies, ending modern slavery, developing greener transport, and reducing reliance on fossil fuels.
The university is a major employer and industry partner - locally and globally - and our graduates are the third most targeted by the UK's top employers, according to The Graduate Market in 2024 report by High Fliers Research.
We lead the Universities for Nottingham initiative, in partnership with Nottingham Trent University, a pioneering collaboration between the city’s two world-class institutions to improve levels of prosperity, opportunity, sustainability, health and wellbeing for residents in the city and region we are proud to call home.
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