Effective gambling messages should curb time and money spent on gambling, since these are the behaviours proximal to gambling-related harm. Studies that aim to find what messages best achieve these objectives are scarce, and most focus on electronic gaming machine (EGM) gambling rather than sports and race betting. The present study aimed to gather longitudinal evidence on previously identified messaging strategies. In an experiment, two types of messages, positive-emotional and norm-based, were contrasted against a control condition with generic messages (e.g., gamble responsibly). By stratified random assignment, participants (N = 2,074, 36% female), were exposed to 3 unique messages in each of 3 weeks, exclusive of pre- and post-surveys in weeks 1 and 5, respectively. There were no significant differences by condition in amounts-bet commercially on sports or race betting, time spent gambling, gambling-harm experienced, gambling-urges nor risk-related gambling beliefs. However, there was a significant decrease in all these outcomes over weeks 1 through 5. The messages may not have been the factor that contributed to the decrease in outcomes over time, as participating in the study may have also prompted self-reflection on gambling expenditure. Positive-emotional messages were rated most helpful and easily understood, and the highest-rated message was the control message, "only bet what you can afford." Despite no differences found between the conditions, the present study provided evidence that self-reflection on gambling expenditure is well-rated by gamblers as being helpful. Future experiments should be conducted to gauge the robustness of this finding.
Keywords: Bet; Betting; Experiment; Messaging; Race; Sports; Trial; Wagering.
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