Louis Shaw
Research Advisor
Adding odds information in an easy-to-understand format (“lose £7 for every £100 bet on average”) to slot game adverts slightly increased demand and trust in a recent online experiment. An increase in demand is surprising, but might be explained by people’s aversion to ambiguity or limited understanding of odds information. Our results suggest that regulators should consider mandating odds information, but only after testing alternative ways to present it.
Spot the difference
In 2023, we ran an online experiment testing the impact of advert features on slot gambling behaviour. Between the pilot and the launch, we accidentally made a small change to one of the tested adverts below. Can you spot it?
The phrase “Players of Fruit Rush lose £7 for every £10 bet on average” above the left-hand ad should have said “lose £7 for every £100” (right-hand ad).
So the advertised expected return, also known as return to player (RTP), dropped from 93% to 30%, which is a large difference. We spotted the typo too late and ended up testing both the high and the low RTP ad. We used this ‘mistake’ to answer three research questions:
- Does RTP information affect player behaviour?
- Do people read RTP information on adverts?
- Does the RTP change feelings towards the advert?
(By the way, presenting RTP information as “lose £7 for every £100” is unusual – normally a gambling operator would not report the RTP on adverts, or would say “this game has an average percentage payout of 90%”. This format was based on our previous research showing that avoiding percentages makes people more likely to understand odds information.)
Finding 1: return to player information changes player behaviour
Those who saw the ad with a 93% RTP were more likely to think they would win money than those who did not see any RTP information, although a 93% RTP still means players should expect to lose money. Participants seeing a ‘high RTP’ (93%) were also marginally more likely to play the game than those seeing a ‘low RTP’ (30%) or no RTP information.
In the second part of the experiment, participants were shown the advert in more detail and asked whether they wanted to play a slot game with money they had “earned” at the start.
There was tentative evidence that seeing the higher RTP of 93% increased the proportion of participants choosing to play the game compared to the ‘low RTP’ advert (51% vs 47 %, p = 0.068) and when no RTP was present (51% vs 48%, p=0.088). This indicates that participants correctly perceived a higher RTP as more appealing, and may prefer adverts including an RTP to adverts without one (though the no RTP advert contained other changes, for example not having the addiction warning).
The differences in play behaviour between the ‘high RTP’ and ‘low RTP’ ads were very small given the large change in RTP. This may reflect the relatively small amounts of (house) money at stake in this experiment, or that participants may not have read the text on the RTP before deciding. We found evidence for the latter by looking at the differences in the rates of play among those who played slot games at least once in the last 12 months.
The increase in play rates when showing the high RTP was entirely due to people who had gambled in the year prior to the experiment. This suggests people who gamble are more likely to pay attention to the RTP.
Why was demand slightly higher when providing information about how much people would lose? We found evidence that financial motives might have been more important in driving the decision to play when we corrected the RTP information. We asked everyone, after they had chosen to play or not, whether they thought they would finish with more or less money than they started with.
There was a 7 percentage point increase in those thinking they’d win money after seeing the ‘high RTP’ advert compared to the no RTP advert (21% vs 14%, p<0.001). This indicates that providing an RTP for a given slot game makes people more confident they’ll win money, despite the RTP showing how much they can expect to lose. A potential explanation is that people assume that the RTP for a slot game is low when this information is not provided, or that ambiguity aversion (that is, the preference for known over unknown risks) leads them to avoid games where this information is not given. Similarly, 11 percentage points fewer participants thought they’d lose money in the ‘high RTP’ ad compared to the ‘low RTP’ one (62% vs 51%, p<0.001).
Finding 2: adding return to player information to the ad improved trust
Trust towards the advert increased by five percentage points when we added ‘high RTP’ information, but there was no statistically significant difference for ‘low RTP’ information. This might be because trust is linked to both transparency and fairness, and participants might have perceived the ‘low RTP’ as unfair.
Finding 3: The majority didn’t notice the return to player information on the advert
Those who recalled seeing a gambling advert on their simulated social media feed were asked what they remembered, based on the approximately 4 seconds they spent looking at it.
Participants seeing the ‘low RTP’ advert were more likely to recall that the RTP wasn’t 94% (36% vs 30% for ‘high RTP’), suggesting the abnormally low RTP caught their attention.
Who paid attention to the RTP information in the typo ad? Among those who hadn’t gambled in the last year, 25% answered the RTP question correctly, independently of which RTP they saw. However, those who had gambled recently were more likely to answer correctly after seeing the ‘low RTP’ than the ‘high RTP’ ad (40% vs 33%, p=0.025). This suggests that those who had gambled the year before were more attentive to the typo in general, and might be more sensitive to differences in RTPs.
Implications
The RTP tells the consumer how much of their money they can expect to win back were they to play a slot game many times. However, operators are currently only required to display this information in the T&Cs for a game, not in the ad itself. We show that those people who have gambled recently do pay attention to and adjust their behaviour in response to the RTP being displayed. Including this information in ads therefore increases transparency in a meaningful way and can help consumers make more informed decisions about their decision to gamble. It may also help with deshrouding a significant UK market and potentially encourage greater competition among operators.
However, we also show that people’s understanding of RTPs, even when framed in natural units, might be limited: a 93% RTP means one can expect to lose 7% of all money staked, on average, yet players seeing accurate RTP information were more likely to think they would win money than those who did not see RTP information on an ad. This might explain why more people decided to play the slot game after seeing this ‘high RTP’. We recommend continuing to test alternative measures of a slot game’s payout on adverts to avoid inadvertently encouraging risky behaviours. The natural units framing of the RTP used in this study was found to be the best understood among average payouts, but the average payout may not be the best statistic to use to help consumers understand whether they are likely to win. As the distribution of slot payouts is not symmetric, the RTP doesn’t represent a “typical” session and can be a misleading anchor. Alternatives to average payouts include the median session’s RTP or the percentage of sessions that have won money.
