“99% of gamblers lose in the long run”: An experimental comparison of novel and pre-existing harm prevention (safer gambling) messages warning about the likelihood of losing money

Harm prevention (safer gambling) messages are often used as a population-based intervention against gambling-related harm, and independently-designed messages (e.g., “Chances are you’re about to lose”) are increasingly replacing industry-designed slogans(e.g., “Take time to think”). One common type of harm prevention message warns people about the likelihood of losing money in gambling (e.g., “99% of gamblers lose in the long run”), but this intervention can potentially be improved by testing pre-existing messages against novel alternatives. We asked UK-based online gamblers (N=4,025) to rate ten pre-existing and novel messages on 7-point scales relating to one potential negative impact (challenging participants to try to win at gambling), and three potential positive impacts (making participants want to gamble less, and being perceived as relevant to the participant and to gamblers experiencing harm). Participants also completed the Problem Gambling Severity Index (PGSI) to explore potential interaction effects based on levels of harm. Messages were all on average perceived as not challenging participants to try to win; as making them want to gamble less; and as being most relevant to gamblers experiencing harm. Significant differences were observed between messages, with “99%of gamblers lose in the long run” scoring the best overall, and the five pre-existing messages currently used in Australia, Belgium, and the UK scoring the worst. Messages were more likely to be seen as a challenge by participants with higher PGSI scores. Continual message design and evaluation can help improve the effectiveness of harm prevention messages.