Vol.:(0123456789) International Journal of Mental Health and Addiction (2024) 24:347–380 https://doi.org/10.1007/s11469-024-01414-w ORIGINAL ARTICLE Effectiveness of Public Messaging Within the Gambling Domain: A Systematic Review Devashish Ray1   · Katie Thomson2 · Fiona R. Beyer2 · Oleta Williams2 · Akvile Stoniute2 · Oluwatomi Arisa2 · Ivo Vlaev3 · Emily J. Oliver1 · Michael P. Kelly1,4 Accepted: 30 October 2024 / Published online: 12 November 2024 © Crown 2024 Abstract Gambling messaging is one potential component of a public health approach towards reducing gambling-related harm (GRH). This systematic review examined the effectiveness of existing public health gambling messaging interventions. Four databases were searched from inception to June 2023. Twenty-one papers met inclusion criteria. Studies were con- ducted in diverse settings, employed various designs, and evaluated messaging interven- tions that differed in their aims and reported outcomes. Interventions were categorised into three groups: general population-level messaging, gambling harm reduction messages, and product risk warnings. The evidence—currently limited—suggests that existing gambling messaging interventions are ineffective in changing behaviours but can raise awareness of GRH. Our findings underpinned recommendations for how the format and presentation of currently used ‘safer’ gambling messages and product warning labels may be improved. Research is required to develop and test messages that can help prevent and reduce GRH both for the general population and people who gamble. Keywords  Systematic review · Gambling-related harms · Public health · Messaging interventions Emily J. Oliver and Michael P. Kelly are joint last authors. * Devashish Ray devashish.ray@newcastle.ac.uk 1 NIHR Policy Research Unit in Behavioural and Social Science ‑ Population Health Sciences Institute, Faculty of Medical Sciences, Newcastle University, Baddiley‑Clark Building, Richardson Road, Newcastle Upon Tyne NE2 4AX, UK 2 Evidence Synthesis Group/NIHR Innovation Observatory, Population Health Sciences Institute, Faculty of Medical Sciences, Newcastle University, The Catalyst, 3 Science Square, Newcastle Upon Tyne NE4 5TG, UK 3 NIHR Policy Research Unit in Behavioural and Social Science ‑ Behavioural Science Group, Warwick Business School, University of Warwick, Coventry CV4 7AL, UK 4 Department of Public Health and Primary Care, Cambridge Public Health, University of Cambridge, Forvie Site, Cambridge CB2 0SR, UK http://orcid.org/0000-0003-1822-6334 http://crossmark.crossref.org/dialog/?doi=10.1007/s11469-024-01414-w&domain=pdf International Journal of Mental Health and Addiction (2024) 24:347–380 Gambling harm has been identified as an important public health issue (Goyder et  al., 2020). Gambling availability, participation, and expenditure have increased in recent years, facilitated by a growth in internet sites (Abbott, 2020). Gambling-related harms (GRH) are wide-ranging and diverse, including increased risks of homelessness, domestic violence, debt, family breakdown, depression, and suicide (Cowlishaw & Kessler, 2015). The most socio-economically deprived and disadvantaged groups have the highest levels of harmful gambling, and they are the most at risk of harm (OHID, 2019). There is also evidence to suggest that prolific gambling marketing has led to the normalisation of gambling for chil- dren and young people (Emond & Griffiths, 2020). Independent research has demonstrated that young people see gambling products and marketing in a range of social, physical, and online settings—from shopping centres to social media sites (Pitt et al., 2023). Research has highlighted that children and young people are at risk of financial and emotional harm from in-game chance-based mechanisms such as slot machines and loot boxes (Montiel et  al., 2022). Given this context, there is a view that preventing GRH requires a public health approach, which refers to a ‘whole of population’ intervention strategy focused on prevention and early intervention (Johnstone & Regan, 2020). Messaging aimed at preventing and/ or reducing GRH is one type of public health approach toward (potentially) reducing GRH, already used in tobacco control and alcohol harm reduction (Wakefield et  al., 2010). Even when messages produce small changes in behaviour at an individual level, their broad application can nevertheless yield meaning- ful positive impacts on population health outcomes. There are several types of messaging strategies currently in use to prevent or reduce GRH (McMahon et al., 2019; Regan et al., 2022). Messaging types vary based on the audience, communication platforms, and spe- cific objectives (Dickson-Gillespie et al., 2008). Primary prevention messaging is designed to provide education, raise awareness of risks and harms, encourage ‘safer’ behaviours, and promote awareness of the availability of appropriate help. The goal of these messages is to prevent GRH from taking root in the first place by focusing on preventing or postpon- ing initiation into potentially harmful gambling behaviours. Secondary prevention messag- ing is designed to interrupt harmful gambling behaviours in their early stages and prevent further harm. These messages focus on self-awareness, ‘responsible’ gambling tools (e.g. self-assessment, limit-setting, self-exclusion, behavioural feedback, real-time pop-up warn- ings), and encouraging individuals to seek help. By intervening early, these messages aim to prevent gambling from progressing to more severe harm while promoting ‘safer’ gam- bling practices and support-seeking behaviours. Currently, public health messaging aimed at prevention or reduction of GRH is domi- nated by a focus on individual-level behaviour and personal responsibility (Marko et al., 2023). Evidence from gambling and other areas of health has shown that when personal responsibility messages are internalised, they may result in stigma and stress, lead to worse overall health outcomes, and create greater health disparities (Marko et al., 2022). In response to concerns about the phrases ‘responsible gambling’ and ‘responsible gam- bling messages’ which imply that people who experience GRH have behaved irresponsibly and should be able to control their gambling (Miller & Thomas, 2017), the industry has adopted the terms ‘safer gambling and safer gambling messages’ (Miller & Thomas, 2018). As the focus remains on individuals, there is to our knowledge no evidence to date of any meaningful difference between these and responsible gambling messages in terms of how they are perceived by the public or affect outcomes. There have been some recent shifts in rhetoric concerning the regulation of gambling. For example, in 2019, the UK Gambling Commission (regulator of the gambling indus- try) adopted a national strategy to reduce GRH (Gambling, 2019). The Commission views 348 International Journal of Mental Health and Addiction (2024) 24:347–380 population-based ‘safer gambling’ campaigns and point-of-sale ‘safer gambling’ messages, as components of ‘universal measures for the benefit of the whole population’. ‘Safer gam- bling’ messages are commonly applied to billboards, television, newspaper, and radio advertisements, and can be shown in gambling venues and on specific gambling products. More recently, the Commission has called for operators to provide clear and consistent risk warning labels on gambling products as one measure to promote ‘safer’ gambling (Gam- bling, 2022). Researchers have proposed that gambling product messages that are designed to enable cross-product comparisons of product risk can be considered a public health intervention to promote ‘safer’ gambling practices while preserving freedom of consumer choice (P. Newall et al., 2023a, 2023b). It has been suggested that warning labels on gam- bling products can modify erroneous cognitions and biases and lead to better informed product choices. Effective gambling-focused messaging could draw from existing evidence and theory concerning health-related behaviour change. Change in behaviour, especially habitual behaviour, occurs through stages, and cycling through the stages is viewed as a natural part of the change process (Prochaska et al., 1997). Notwithstanding the criticisms directed at the conceptual validity of the stages of change approach (Armitage, 2009), an integrative stage of change theoretical model that has been successfully applied to health and risk mes- saging is the Transtheoretical Model (TTM) (Noar, 2017). The TTM highlights the need for awareness and sufficiently motivating beliefs and attitudes prior to individuals’ develop- ing an intention to take action(s) to change their behaviours. There is evidence that appro- priate messaging (in terms of content, channel, etc.) can influence both these determinants and an individual’s decision-making concerning engagement (Wakefield et  al., 2010). However, it is important to acknowledge that messaging alone is unlikely to change inten- tions and behaviours. Decisions are context-dependent, and an individual is always subject to a wide range of environmental and contextual influences (e.g. advertising; accessibility of gambling products and premises) (Livingstone et al., 2019). While messaging and com- munications targeting the individual are important, upstream changes to the environment in which gambling takes place (including structural and legislative changes and social influ- ences from peers, social groups, and the wider community) will also be required to play a substantial role in behaviour change (Regan et al., 2022). The UK government has stated plans to replace industry-led gambling messaging with independently developed messaging by drawing on public health, behavioural science, and social marketing expertise (DCMS, 2023). Evidence-based guidance is required for the development of population-level public health gambling messaging that can contrib- ute to meaningfully preventing GRH whilst avoiding stigmatisation. To our knowledge, no review has focused on public health gambling messaging aimed at the prevention of GRH as yet. Therefore, this review systematically evaluated the evidence for the effectiveness of existing gambling messaging interventions that have a focus on primary prevention. Methods This systematic review is reported in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA 2020) guideline (Page et  al., 2021) (Supplementary file S1) and was pre-registered at PROSPERO (https://​www.​crd.​york.​ ac.​uk/​prosp​ero) as CRD42023435519. An important amendment was made to the pro- tocol after the study selection process was completed regarding the choice of tool(s) to 349 https://www.crd.york.ac.uk/prospero https://www.crd.york.ac.uk/prospero International Journal of Mental Health and Addiction (2024) 24:347–380 assess the methodological quality of the studies. In view of the diverse research designs of the included studies, it was felt that we would experience difficulties with using the ROBINS-I tool (Sterne et al., 2016) for all the experimental studies, and that the range of critical appraisal tools available from the Joanna Briggs Institute (JBI) would be the best option (Barker et al., 2023). The JBI offers a range of critical appraisal instruments that are designed to study design-specific and are presented as questions in a checklist (Barker et  al., 2023). There are checklists specific to quantitative data such as randomized con- trolled trials, quasi-experimental studies, analytical cross-sectional studies, and data spe- cific to qualitative research. Inclusion Criteria For this research, we defined public health gambling messaging as messaging with a focus on the primary prevention of GRH. These messages are designed to engage the public (including consumers) with information, with the aim of increasing their awareness and knowledge, shifting their attitudes towards gambling, and ultimately changing practices that (potentially) prevent GRH before they arise. We conceptualised population-level mes- saging interventions as those that may be directed to an entire population or a large, broad group of people within a community. Primary research studies of any study design and conducted in any country and reported in English were eligible. The inclusion criteria were determined a priori in terms of PICO (Population, Intervention, Comparator, Outcome) (Thomas et  al., 2019) and are summa- rised in Table 1. Exclusion Criteria The following studies were excluded: Table 1   PICO elements of the systematic review Population Recipients of the messaging intervention were individuals 11 years old* or more. (*11 years is the lowest age at which gambling participation prevalence data is reported in the UK by the Gambling Commission) Intervention(s) Messaging aimed at providing information about (a) risks and harms of gambling (e.g. campaigns), (b) gambling practices that are expected to prevent and/ or reduce GRH (e.g. ‘safer’ gambling messages), and (c) product risk messages that are designed to enable cross-product comparison of product risk Comparator None Outcomes Studies reporting on: Social cognitive variables (knowledge, attitudes, beliefs, intentions) Stigma (where it occurs) Behavioural outcomes (e.g. reducing overall gambling activities, adopting gambling prac- tices that are viewed as harm-reducing, and accessing help and support) Exposure outcomes (e.g. message recall, acceptability of the message, engagement with, and understanding of the message) Views about the perceived effectiveness of message, message design, content, and delivery strategy Study design Any 350 International Journal of Mental Health and Addiction (2024) 24:347–380 • Not peer-reviewed. • Not written in English • Opinions/review articles • Exploratory research on views about gambling public health messaging • Messaging intervention involving individual person to person delivery • Educational interventions (e.g. school-based educational programmes) • Evaluation of gambling harm prevention campaigns that did not involve messaging • Studies that evaluated gambling messaging targeted those who have already started gambling and may be experiencing GRH (secondary prevention), e.g. pop-up warning messages presented during a live gambling session, self-assessment tools, limit-setting and self-control tools, self-exclusion strategies, personalised behavioural feedback Search Strategy The following databases were searched from inception to 9th June 2023: Medline (OVID), EMBASE (OVID), PsycINFO (OVID), and Applied Social Sciences Index & Abstracts (ProQuest). The key concepts used in the search were gambling, communications, and mass media campaigns. An example (Medline) search strategy is shown in suppl. file S2. Forward and backward citation searching of the included studies was undertaken, and reference lists of relevant published reports and opinion pieces were also assessed. Screening of titles, abstracts, and full-text papers was undertaken in duplicate (AS, DR) using Rayyan (Ouz- zani et al., 2016). Screening conflicts were resolved via discussion, or with a third reviewer (KT/FB). Data were extracted onto a bespoke data extraction form by DR and checked in full by OA. Data were extracted on study characteristics (e.g. study year, location, fund- ing source, study design), recruitment strategy, participant characteristics, purpose and details of interventions, and outcome measures relating to social cognitive variables, expo- sure outcomes, stigma, or behaviour change. Qualitative data were also captured relating to views about the message content and effectiveness. The methodological quality of each study was assessed using the relevant JBI critical appraisal tool (Barker et  al., 2023). DR and OA (or KT) independently appraised each study, and disagreements were resolved by discussion with a third reviewer (KT or FB). The substantial heterogeneity of the intervention aims, study design, and reported out- come measures across the studies precluded meta-analysis. Therefore, a narrative syn- thesis of the data, primarily in terms of study setting, design, type of intervention, and outcome(s), was completed (Popay et al., 2006). A stepped iterative process was followed to synthesise the data: developing a primary synthesis, exploring the relationships between and within studies, and assessing the robustness and quality of the evidence. Results Results of the Searches Searches generated 1086 unique results and 33 of these (including 12 from citation and manual searching) were assessed as eligible for full-text assessment (Fig. 1). Twenty-one papers were considered eligible and included in this review. Information about the full-text 351 International Journal of Mental Health and Addiction (2024) 24:347–380 papers (n = 12) that were excluded including the reason for exclusion is presented in suppl. file S3. Included Studies Characteristics of the included studies are shown in Table 2. Of the 21 studies, six each were conducted in the USA and the UK, five in Canada, two in New Zealand, and one each in Australia and France. The papers were published between 2000 and January 2023. Sixteen papers reported funding from non-industry sources (either academic or independ- ent research institutions and/ or government bodies). Five papers (of these, four reported funding from non-industry sources) reported that the first author of the paper previously received grant funding from and contributed to research funded by GambleAware, a UK charity organisation that receives donations from gambling operators. Four papers did not provide funding information. One paper explicitly reported funding from the gambling industry. The studies were conducted over a range of settings (e.g. mass media, field studies, laboratory, and online experiments). The study designs were cross-sectional (n = 4), quasi- experimental (n = 3), non-randomised experimental studies with control group(s) (n = 2), randomised experimental studies with control group(s) (n = 11), and one qualitative study. We categorised the studies into three broad groups based upon the type of messaging eval- uated by the study: 1. Messaging targeting the general population: seven studies evaluated messaging aimed at or intended for the general population for a particular period of time, using specific communication activities (e.g. billboards, posters, or mass media campaigns), target- ing gambling behaviours or related social cognitive (knowledge, awareness, beliefs) Records identified from: MEDLINE (n= 479) PsycInfo (n= 677) Embase (n= 456) ASSIA (n= 168) Total = (n=1780) Records removed before screening: Duplicate records removed (n = 706) Titles and abstracts screened (n = 1074) Records excluded (Not met eligibility criteria) (n = 1053) Papers sought for retrieval (n = 21) Papers not retrieved (n = 0) Full text papers assessed as eligible (n = 12) Reports excluded1:9 Not in English (n = 1) Opinion/ review article (n = 2) Wrong intervention (n = 5) Exploratory research (not an intervention) (n=1) Citation and manual searches: Titles and abstracts screened (n = 12) Full text papers assessed as eligible (n = 9) Reports excluded:3 Wrong intervention (n = 3) Studies included in review (n = 21) (12 from databases and 9 from citation searching) Identification of studies via databases Identification of studies via other methods Id en tif ic at io n Sc re en in g In cl ud ed Papers sought for retrieval (n = 12) Papers not retrieved (n = 0) Fig. 1   PRISMA 2020 flow chart. The first reason for exclusion is recorded 352 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   C ha ra ct er ist ic s o f t he in cl ud ed st ud ie s ( lis te d in th e or de r o f t he ir pu bl ic at io n da te , f ro m m os t r ec en t t o ol de st) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity N ew al l ( 20 23 ); U K O nl in e la b ex pe ri- m en t Te sti ng o f ‘ Ta ke Ti m e to T hi nk ’, a U K sa fe r g am - bl in g m es sa ge ; ra nd om is ed co nt ro lle d stu dy (R C S) n =  22 78 ; 4 2. 4% fe m al es , 5 6. 6% m al es ; 2 20 pa rti ci pa nt s as se ss ed a s ‘p ro bl em g am - bl er s’ 3 ex pe rim en ta l co nd iti on s: n o m es sa ge (c on - tro l), m es sa ge co nd iti on a nd m es sa ge  +  co n- di tio n (a dd l. po p- up m es sa ge be fo re p la y) Va rio us g am bl in g pr ac tic es H ig h N o st at ist ic al ly si gn ifi ca nt c re d- ib le p ro te ct iv e eff ec ts o f t he m es sa ge N o N ew al l ( 20 22 ); U K O nl in e la b ex pe ri- m en t Te st th e eff ec ts o f ‘W he n th e Fu n St op s, St op ’ ( a U K sa fe r g am - bl in g m es sa ge ); RC S (3 R C Ss w er e co nd uc te d) Ex pe rim en t (E xp t) 1: n =  50 6, 3 3· 2% fe m al es ; E xp t 2 : n =  15 00 , 3 8· 5% fe m al es ; E xp t 3 : n =  10 03 , 3 5% fe m al es Th re e ex pe ri- m en ts ; E xp ts 1 an d 3 in vo lv ed be ts o n so cc er ev en ts ; E xp t 2 us ed a n on lin e ro ul et te g am e Va rio us g am bl in g pr ac tic es M ed iu m N o ev id en ce th at th e pr es en ce of a g am bl in g m es sa ge in flu en ce d pa rti ci pa nt s’ pr op en si ty to g am bl e on sp or tin g ev en ts N o; N ot e: N ew al l ha s p re vi ou sly co nt rib ut ed to pr oj ec ts fu nd ed by G am bl eA w ar e (a n in du str y- su pp or te d U K C ha rit y) 353 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity N ew al l ( 20 21 ); U K O nl in e la b ex pe ri- m en t Ex pl or e th e im pa ct o f p er - ce nt ag e fr am in g an d cu rr en cy fr am in g fo r w ar ni ng la be ls ; RC S (3 R C Ss w er e co nd uc te d) n =  10 07 ; 5 4. 3% fe m al es , 4 5. 6% m al es Pa rti ci pa nt s re ce iv ed e ith er pe rc en ta ge or c ur re nc y- fr am ed h ou se - ed ge w ar ni ng la be ls a nd su bs eq ue nt ly ga ve th ei r p er - ce iv ed c ha nc e of w in ni ng B el ie fs : p er ce iv ed ch an ce s o f w in ni ng ; b eh av - io ur : g am bl in g co ns um pt io n M ed iu m N o re lia bl e eff ec t of p er ce nt ag e or c ur re nc y fr am in g of ho us e- ed ge w ar ni ng la be ls ; pa rti ci pa nt s’ pe rc ei ve d ch an ce s o f w in ni ng w er e eq ua lly re sp on si ve to va ria tio ns in th e ‘p ric e’ o f g am - bl in g, a cr os s bo th c on di tio ns N o; N ot e: N ew al l ha s p re vi ou sly re ce iv ed g ra nt fu nd ed b y G am bl eA w ar e 354 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity H or n (2 02 1) ; U SA La b ex pe rim en ts Ex pl or e ho w un iv er si ty stu de nt s i ns pe ct an d un de rs ta nd lo tte ry ti ck et w ar ni ng m es - sa ge s; R C S (2 R C Ss w er e co nd uc te d) St ud y 1: n  =  64 , 77 % fe m al es ; St ud y 2: n  =  47 , 53 % fe m al es St ud y 1 ob se rv ed pa rti ci pa nt s’ in te ra ct io ns w ith w ar n- in g m es sa ge s; St ud y 2 te ste d eff ec t o f p la ce - m en t o f t he w ar ni ng Re co gn iti on , un de rs ta nd in g, an d ra tin g of w ar ni ng m es - sa ge s Lo w A cr os s b ot h stu di es , ‘ Pl ay re sp on si bl y’ w ar ni ng m es - sa ge re po rte d as c om pr e- he ns ib le , b ut pa rti ci pa nt s d id no t a ss oc ia te th e ph ra se w ith in fo rm at io n ab ou t g am bl in g ris ks a nd m an y fe lt th e ph ra se w as n ot re le va nt to th em N o 355 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity N ew al l ( 20 20 b) ; U K O nl in e la b ex pe ri- m en ts In ve sti ga te e ffe ct s of w ar ni ng m es sa ge fo rm at an d vo la til ity st at em en t; RC S (2 R C Ss w er e co nd uc te d) n =  20 25 (a ll w ith on lin e ga m bl in g ex pe rie nc e) ; 43 .8 % fe m al es M es sa ge s ( tw o in ‘h ou se -e dg e’ fo rm at a nd tw o in ‘r et ur n to pl ay er ’ f or m at ) w er e cr os se d w ith th e fa ct or of v ol at ili ty st at em en t p re s- en ce O bj ec tiv e pr od uc t m es sa ge u nd er - st an di ng ; p er - ce iv ed c ha nc es of w in ni ng M ed iu m O ve ra ll, b ot h ve rs io ns (w ith an d w ith ou t th e vo la til ity st at em en t) of th e ho us e- ed ge m es sa ge w er e un de rs to od be tte r t ha n bo th re tu rn -to -p la ye r m es sa ge s. Th e ho us e- ed ge fo rm at a nd th e pr es en ce of v ol at ili ty st at em en ts bo th a dd iti ve ly re du ce d ga m - bl er s’ p er ce iv ed ch an ce s o f w in ni ng N o; N ot e: N ew al l ha s p re vi ou sly co nt rib ut ed to re se ar ch p ro je ct s fu nd ed b y G am bl eA w ar e 356 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity N ew al l ( 20 20 a) ; U K O nl in e la b ex pe ri- m en ts C om pa re p la ye r’s (a ) p er ce iv ed ch an ce o f w in ni ng a nd (b ) u nd er st an d- in g of w ar ni ng la be ls ; R C S A ll ha d ex pe ri- en ce o f o nl in e ga m bl in g; E xp t 1: n  =  39 9, 50 .5 % fe m al es ; Ex pt 2 : n  =  40 7, 56 .8 % fe m al es Fa ct ua lly e qu iv a- le nt w ar ni ng s pr es en te d ei th er in ‘h ou se - ed ge ’ f or m at or ‘r et ur n to pl ay er ’ f or m at Pe rc ei ve d ch an ce s of w in ni ng ; un de rs ta nd in g of th e di ffe re nt m es sa gi ng fo rm at s M ed iu m Pe rc ei ve d ch an ce s of w in ni ng w er e hi gh er u nd er th e re tu rn -to - pl ay er fr am e an d hi gh er fo r hi gh er v al ue s of th e re tu rn - to -p la ye r; ho us e- ed ge w ar ni ng la be l w as u nd er sto od m or e cl ea rly b y al l g am bl er s N o; N ot e: N ew al l ha s p re vi ou sly re ce iv ed a gr an t f un de d by G am bl eA w ar e N ew al l ( 20 19 ); U K O nl in e la b ex pe ri- m en ts (1 ) T es tin g of th e m es sa ge (W he n th e Fu n St op s, St op ”; (2 ) t es t eff ec ts o f m es - sa ge m an ip ul a- tio n; R C S U K n at io na ls , so cc er fa ns , a nd on lin e sp or ts be tte rs ; n  =  50 6, 66 .7 % m al es , 33 .3 % fe m al es Pa rti ci pa nt s m ad e ch oi ce s o ve r ni ne £ 0. 10 b et s fo r a n up co m - in g fo ot ba ll m at ch Va rio us g am bl in g pr ac tic es M ed iu m Th e te ste d m es - sa ge d id n ot ac hi ev e its de si re d eff ec t of p ro m pt in g m or e re sp on - si bl e ga m bl in g be ha vi ou r an d de cr ea s- in g ga m bl in g be ha vi ou r U nc le ar ; N ot e: D ur in g th is stu dy ’s ti m e fr am e, N ew al l re ce iv ed a re se ar ch g ra nt fu nd ed b y G am bl eA w ar e 357 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity W al ke r ( 20 19 ); U SA La b ex pe rim en ts Ex am in e ho w di ffe re nt in fo rm at io n pr es en ta tio n fo rm at s i nfl u- en ce g am bl in g- re la te d ju dg e- m en ts ; R C S (2 R C Ss w er e co nd uc te d) n =  20 1, 1 02 m al es , 9 0 fe m al es ; E xp t 2: n  =  20 1, 11 9 m al es , 8 1 fe m al es Ex pt 1 : V er si on s of g am e ca rd s pr ov id ed d if- fe re nt p ay ba ck pe rc en ta ge s a nd un cl ai m ed p riz e in fo rm at io n. Ex pt 2 : i nv es ti- ga te d w he th er gr ap hi ca lly de pi ct in g pa y- ba ck p er ce nt ag e aff ec ts u se o f th is in fo rm at io n U nd er st an di ng of p ay ba ck pe rc en ta ge in fo rm at io n; be lie fs : c ha nc es of w in ni ng ; ca rd p ur ch as in g in te nt io n M ed iu m Ex pt 1 : R at in gs of li ke lih oo d of w in ni ng , ex ci te m en t, ur ge to g am bl e, ca rd p ur ch as in g w er e al l h ig he r fo r c ar ds w ith gr ea te r n um be rs of u nc la im ed pr iz es ; E xp t 2 : Th e pr ef er en ce pa tte rn n ot ed in e xp er im en t 1 w as re ve rs ed w he n pa yb ac k pe rc en ta ge w as p re se nt ed in a g ra ph i- ca l f or m at ; pa rti ci pa nt s’ pr ef er en ce s w er e co ng ru en t w ith th e tru e ex pe ct ed v al ue of th e pr es en te d sc ra tc h ca rd s N o 358 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity D ie hr (2 01 8) ; U SA St ud en t r es id en ce ha lls o f a u ni - ve rs ity A ss es s s tu de nt s’ re sp on se s t o tw o po ste r, ca si no be tti ng a nd sp or ts b et tin g, cr os s- se ct io na l n =  43 1, m al es 21 2, fe m al es 21 5; 3 4% h ad ga m bl ed in th e la st ye ar D is pl ay o f 4 0 po ste rs fo r a w ee k M es sa ge a pp ea l; un de rs ta nd - in g of , a nd ag re em en t w ith m es sa ge H ig h Po ste r m es sa ge s ra te d as a pp ea l- in g, c re di bl e, an d co m pr eh en - si bl e N o M ou ne yr ac (2 01 7) ; F ra nc e M ul ti- na tio n on lin e stu dy Ev al ua te c om - m un ic at iv e an d pr ev en tiv e va lu es o f E ur o- pe an g am bl in g pr ev en tio n m es - sa ge s; C ro ss - se ct io na l n =  33 9 (a na ly se d sa m pl e) ; 7 2. 6% fe m al es ; 5 1% re po rte d ha vi ng ga m bl ed in th e pa st 14 m es sa ge s w er e ev al ua te d: re sp on si bl e ga m bl in g (n  =  5) , r is k in fo rm at io n (2 ); co rr ec tin g er ro - ne ou s b el ie fs (n  =  7) Pe rc ei ve d co m - m un ic at iv e an d pr ev en tiv e va lu e of th e m es sa ge ; ra nk in g of th e m es sa ge s ( m os t to le as t p re ve n- tiv e) H ig h M es sa ge s p ro - m ot in g re sp on - si bl e ga m bl in g ju dg ed a s ha vi ng lo w es t co m m un ic a- tiv e va lu e as co m pa re d to m es sa ge s in fo rm in g ab ou t ris ks a nd m es - sa ge s c or re ct in g er ro ne ou s be lie fs . M es - sa ge s i nf or m in g ab ou t t he ri sk s ra nk ed h ig he st fo r c om m un ic a- tiv e an d pr ev en - tiv e va lu e N o 359 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity C al de rw oo d (2 01 5) ; C an ad a Fi el d stu dy (c om m er ci al ar ea s w ith in a C ou nt y) ; Ev al ua te th e im pa ct o f t w o m es sa ge s d is - pl ay ed o n ro ad - si de b ill bo ar d po ste rs ; Q ua si - ex pe rim en ta l: (p re -p os t) Es tim at ed 1 9% o f th e po pu la - tio n (~  91 ,2 90 pe op le ) w er e ex po se d Fo ur to e ig ht bi llb oa rd s w er e po ste d ov er a 24 -w ee k pe rio d, w ith lo ca tio ns ch an ge d in 4- w ee k cy cl es Ex po su re to bi llb oa rd s: aw ar en es s o f th e ca m pa ig n H ig h A dm is si on ra te s t o PG S co nt in ue d to de cl in e; m ai n co m m un ic at io n ch an ne l w as w or d- by -m ou th (n ot b ill bo ar ds ) N o O ra zi (2 01 5) ; U SA O nl in e ex pe ri- m en ts In ve sti ga te im pa ct of fr am in g of re sp on si bl e ga m bl in g m es - sa ge s u si ng tw o ex pe rim en ts : RC S n =  26 0 (o nl y th os e w ho ga m bl ed a t l ea st on ce a m on th ); 64 % w er e m al es St ud y 1: fo cu se d on e ith er th e m at e- ria l o r s oc ia l co ns eq ue nc es of g am bl in g. St ud y 2: fo cu se d on lo ss - vs g ai n- fr am in g of m es sa ge s Pe rc ep tio ns of n at ur e of co ns eq ue nc es (s oc ia l v s m at e- ria l); A tti tu de s to w ar d (a ) ga m bl in g m es sa gi ng a nd (b ) g am bl in g in te nt io ns M ed iu m C om pa re d to m at er ia l c on se - qu en ce s, so ci al co ns eq ue nc es w er e m or e eff ec tiv e in re du ci ng th e pr op en si ty to g am bl e. Th is d iff er - en tia l i m pa ct is st ro ng er am on g pr ob le m ga m bl er s ( vs . re cr ea tio na l ga m bl er s) an d w he n th e co ns eq ue nc es ar e pr es en te d as lo ss es (v s. ga in s) N ot re po rte d 360 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity M ag ill (2 01 3) ; N ew Z ea la nd N at io na l m as s m ed ia c am - pa ig n; Ev al ua te re ac h an d re sp on se to th e th ird p ha se of th e pr ob le m ga m bl in g K iw i Li ve s c am pa ig n; C ro ss -s ec tio na l n =  85 0; 1 st gr ou p (n  =  50 0) : m al es 46 % , f em al es 54 % ; 2 nd g ro up (n  =  35 0) : m al es 56 % , f em al es 44 % C am pa ig n ta rg et ed th os e at h ig he r r is k of e xp er ie nc - in g ha rm s; th e ph ra se ‘C ho ic e no t C ha nc e’ w as u se d in a se rie s o f t el ev i- si on a nd ra di o ad ve rts A w ar en es s a nd re ca ll of k ey m es sa ge s; in te ra ct io n w ith c am pa ig n; se lf- re po rte d be ha vi ou rs an d re sp on se s un de rta ke n or co ns id er ed H ig h H ig h le ve l o f aw ar en es s, ac ce pt ab ili ty , ag re em en t w ith m es - sa ge s; v ie w s: m es sa ge s a re re le va nt , c re d- ib le , t ho ug ht pr ov ok in g, an d lik el y to pr od uc e de si re d ou tc om es N o 361 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity M un oz (2 01 2) ; C an ad a La bo ra to ry (l ab ) ex pe rim en ts in vo lv in g vi de o lo tte ry te rm in al (V LT ) p la ye rs ; no n- ra nd om is ed stu dy w ith c on - tro l g ro up (s A ss es s t he eff ec tiv en es s of (a ) g ra ph ic w ar ni ng s v s. te xt -o nl y; a nd (b ) f am ily v s fin an ci al d is ru p- tio n m es sa ge s; N on -r an - do m is ed st ud y w ith c on tro l gr ou p( s) n =  10 3 (a ll ga m - bl ed o n V LT s re gu la rly ); 60 % m al es ; 7 8. 6% se lf- as se ss ed as p ro bl em ga m bl er s Fa ct or ia l d es ig n ex pe rim en t: a gr ap hi c pi ct ur e de pi ct ed a V LT as a m on ste r ea tin g a ga m - bl er . T he im ag e de pi ct ed th e ne ga tiv e (fi na n- ci al o r f am ily ) ou tc om es th at ga m bl er s m ig ht su ffe r B el ie fs : s ev er - ity o f t hr ea t, vu ln er ab ili ty ; se lf- effi ca cy ; fe ar le ve l; en ga ge m en t w ith w ar ni ng ; at tit ud e; b eh av - io ur in te nt io n H ig h G ra ph ic c on te nt co m bi ne d w ith fa m ily di sr up tio ns w as m or e eff ec tiv e fo r c ha ng in g at tit ud es a nd co m pl yi ng w ith th e w ar ni ng th an o th er co m bi na tio ns o f th e m an ip u- la te d va ri- ab le s. G ra ph ic w ar ni ng s a ls o si gn ifi ca nt ly aff ec te d sh or t- te rm b eh av - io ur al in te nt w he n co up le d w ith fa m ily di sr up tio n co nt en t; te xt - on ly w ar ni ng s si gn ifi ca nt ly aff ec te d sh or t- te rm in te nt if co up le d w ith fin an ci al d is ru p- tio n co nt en t N o 362 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity Th om as (2 01 2) ; A us tra lia N at io na l s oc ia l m ar ke tin g m es - sa ge s Ex pl or e in te ra c- tio n w ith a nd re sp on se to so ci al m ar ke tin g m es sa gi ng c am - pa ig ns ; q ua lit a- tiv e stu dy n =  10 0: 6 2 m al es , 38 fe m al es ; m os t ( 97 ) h ad ga m bl ed in th e pr ev io us y ea r Va rio us d ow n- str ea m so ci al m ar ke tin g m es sa gi ng ca m pa ig ns A w ar en es s o f, an d in te ra ct io ns w ith c am pa ig n; pe rc ep tio n of ris k fa ct or s H ig h 3 th em es : ( i) fo cu s o n in di vi du al s t o ta ke p er so na l re sp on si bi lit y; (ii ) k ey b ar rie r: ov er w he lm - in g vo lu m e of p os iti ve m es sa ge s f ro m th e ga m bl in g in du str y; (i ii) ris k: p re ve nt se ek in g he lp an d re in fo rc e pe rc ep tio ns o f sti gm a N ot re po rte d 363 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity G al la gh er (2 01 1) ; C an ad a Ex pe rim en t i n a fie ld se tti ng Ex am in e eff ec ts of a v id eo lo t- te ry te rm in al (V LT ) w ar ni ng ba nn er ; Q ua si - ex pe rim en ta l: 3 tim e po in ts n =  54 ; 3 2 m al es a nd 2 2 fe m al es ; 2 7 w er e as se ss ed as p ro bl em ga m bl er s A sc ro lli ng ba nn er w as di sp la ye d on V LT sc re en s f or a 2- w ee k pe rio d (b an ne r w as n ot di sp la ye d du r- in g pl ay ) G am bl in g co ns um pt io n be ha vi ou rs H ig h Si gn ifi ca nt de cr ea se in nu m be r o f ho ur s p la yi ng V LT s ( se lf- re po rte d) b y bo th p ro bl em ga m bl er s ( PG s) an d no n- PG s du rin g th e ba nn er p er io d; ov er al l, PG s re po rte d pl ay - in g m or e ho ur s th an n on -P G s; si gn ifi ca nt de cr ea se in fa ul ty g am bl in g be lie fs o nl y in PG s N ot re po rte d 364 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity M un oz (2 01 0) ; C an ad a La b ex pe rim en t in vo lv in g V LT pl ay er s; n on - ra nd om is ed stu dy w ith c on - tro l g ro up (s ) Ex pl or e co gn iti ve an d em ot io na l re sp on se s t o fe ar a pp ea ls ; N on -r an - do m is ed st ud y w ith c on tro l gr ou p( s) n =  25 8 (a ll ga m - bl ed o n V LT s re gu la rly ); 58 % m al es , 4 2% fe m al es Fa ct or ia l d es ig n ex pe rim en t us ed m es sa ge s w ith fo llo w - in g ne ga tiv e ou tc om es : f am - ily d is ru pt io n, fin an ci al fa ilu re , an d su ic id e B el ie fs : s ev er - ity o f t hr ea t, vu ln er ab ili ty ; re sp on se e ffi - ca cy , s el f- effi - ca cy ; f ea r l ev el ; en ga ge m en t w ith w ar ni ng ; at tit ud e; b eh av - io ur in te nt io n H ig h B ot h hi gh er th re at w ar ni ng s a nd th e go ve rn m en t/ m ed ic al so ur ce of w ar ni ng s (in c on tra st to ga m bl in g pr o- vi de r s ou rc e) en ha nc ed D ep th of In fo rm a- tio n Pr oc es s- in g (D IP ). In tu rn , D IP le ve ls a ffe ct ed re sp on se effi ca cy (b el ie fs ab ou t e ffi ca cy of th e m es sa ge ) an d at tit ud e ch an ge (s ig - ni fic an tly a nd po si tiv el y) , a nd in te nt io ns to co m pl y w ith th e w ar ni ng N o 365 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity H al l ( 20 09 ); N ew Ze al an d N at io na l m as s m ed ia c am - pa ig n A ss es s t he re ac h an d re sp on se to th e se co nd ph as e of th e pr ob le m ga m bl in g K IW I Li ve s c am pa ig n; cr os s- se ct io na l n =  15 95 ; 9 00 fe m al es , 6 95 m al es 25 - t o 54 -y ea r- ol ds ; c am pa ig n us ed re al -li fe sto ry re pr es en - ta tio ns (a s T V ad ve rts ) a nd in co rp or at ed th e ph ra se ‘t og et he r w e ca n m ak e it rig ht ’ A w ar en es s a nd re ca ll of k ey m es sa ge s; in te ra ct io n w ith c am pa ig n; se lf- re po rte d be ha vi ou rs an d re sp on se s un de rta ke n or co ns id er ed H ig h H ig h le ve l o f ag re em en t t ha t TV a dv er ts w er e re le va nt an d cr ed ib le , po si tiv e re sp on se s hi gh er fo r yo un g ad ul ts . 16 % sa id th ey ac tu al ly d id so m et hi ng in re sp on se to th e ad s a nd 7 % ad m itt ed h av in g lo ok ed fo r m or e in fo rm at io n ab ou t p ro bl em ga m bl in g N o 366 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity N aj av its (2 00 3) ; U SA St at e- w id e m as s m ed ia c am - pa ig n Ev al ua te im pa ct of th e ca m - pa ig n; q ua si - ex pe rim en ta l: (p re -p os t) n =  80 0; 4 00 pr e- a nd 4 00 po st- ca m pa ig n; 51 .3 % fe m al es , 48 .3 % m al es C am pa ig n de si gn ed to in cr ea se aw ar e- ne ss o f g am - bl in g- re la te d ha rm s; c ha nn el s us ed : r ad io , bi llb oa rd s, br o- ch ur es , n ew s- pa pe r a dv er ts , po ste rs A w ar en es s o f ca m pa ig n; kn ow le dg e ab ou t g am bl in g an d pr ob le m ga m bl in g H ig h 8. 2% re ca lle d se ei ng th e ad s; m or e re ca lle d th e ad sl og an ; ov er al l, ca m - pa ig n vi ew ed po si tiv el y; re sp on de nt s al re ad y se em ed hi gh ly aw ar e of ris ks a nd h ar m s of g am bl in g N o St ee nb er g (2 00 4) ; U SA La b an al og ue stu dy in vo lv in g stu de nt s a t a la rg e ur ba n un iv er si ty Ex am in e im pa ct of w ar ni ng m es sa ge s u si ng a co m pu te ris ed ro ul et te g am e; RC S N  =  10 1 (a ll ha d hi sto ry o f r ec en t ga m bl in g) ; fe m al es 6 4. 4% Pa rti ci pa nt s r an - do m ly a ss ig ne d to re ce iv e a w ar ni ng m es - sa ge , a m es sa ge pl us in fo rm a- tio n on li m it se tti ng a nd ir ra - tio na l b el ie fs o r a vi de o ab ou t ga m bl in g B el ie fs a bo ut ga m bl in g ou tc om es ; pe rc ei ve d se lf- effi ca cy ; kn ow le dg e of od ds a nd ri sk s M ed iu m In te rv en tio n pr od uc ed si g- ni fic an t i nc re as e in k no w le dg e ab ou t r is ks of g am bl in g, re du ct io ns in ir ra tio na l be lie fs , a nd en co ur ag ed se tti ng ti m e an d m on ey li m its . N o ch an ge s w er e ob se rv ed in p er ce iv ed se lf- effi ca cy o r ac tu al g am bl in g be ha vi ou r N o 367 International Journal of Mental Health and Addiction (2024) 24:347–380 Ta bl e  2   (c on tin ue d) St ud y re fe re nc e Se tti ng A im s; st ud y de si gn Pa rti ci pa nt s In te rv en tio n/ ex pe rim en t de ta ils O ut co m es M et ho d- ol og ic -a l qu al ity K ey fi nd in gs Fu nd in g fro m in du str y/ in du str y- su pp or te d ch ar ity La do uc eu r (2 00 0) ; C an ad a Fi el d stu dy (c om - m un ity ); RC S Ev al ua te a br oc hu re o n pa th ol og ic al ga m bl in g; R C S n =  11 5; 5 6 m ak es an d 59 fe m al es B ro ch ur e co ns ist ed o f a ca rto on a nd in fo ab ou t p ro bl em , ga m bl in g ha rm s an d su pp or t se rv ic es U nd er st an di ng o f pr ob le m g am - bl in g, aw ar e- ne ss o f r is ky be ha vi ou rs a nd su pp or t s er vi ce s Lo w C om m en ts ab ou t f or m at an d qu al ity o f in fo rm at io n, an d pe rc ei ve d us ef ul ne ss o f th e br oc hu re w er e m os tly po si tiv e. E xp o- su re in cr ea se d kn ow le dg e of ris ks a nd h ar m s of g am bl in g Ye s Ab br ev ia tio ns : E xp t e xp er im en t, la b la bo ra to ry , R C S ra nd om is ed c on tro lle d stu dy , V LT v id eo lo tte ry te rm in al . 368 International Journal of Mental Health and Addiction (2024) 24:347–380 or behavioural outcomes (attitudes and intentions) for the purpose of minimising or preventing GRH. 2. Gambling harm prevention or reduction messages: five studies evaluated messages that provide players with information about behaviours and strategies, with the aim of increasing their awareness and knowledge of risks and harms of gambling, shifting their attitudes on gambling, and ultimately facilitating behaviours that prevent or reduce GRH. 3. Gambling product labels: nine studies evaluated messages that informed players about risks associated with the product (the messages did not appear during active play), aim- ing to influence risk assessment and decision making before start of play. Studies of messaging campaigns reported the use of quota sampling and other strategies to generate random samples that were demographically representative of the national adult population. Only six studies provided information on the ethnicity/race profile of partici- pants; of these, only two studies stated that minorities were well represented in the sample (Hall & Dickinson, 2009; Steenbergh et al., 2004). Studies that conducted online experi- ments recruited participants using crowdsourcing online platforms or other networks; some of these studies used filter questions (e.g. seriousness of participation, gambling activity status) at the beginning of the experiment to select participants that were likely to pro- vide attentive and complete responses. Most of the studies (10/14) that conducted experi- ments to test harm-reduction messages and/or product warning labels purposively recruited participants who regularly engaged in gambling. Seven studies reported the gambling pro- file of their participant pool, using the Problem Gambling Severity Index, a self-reported screening tool available for use with the general population (Smith & Wynne, 2002). Three studies reported on findings related to problem gamblers; of these, only one study (Orazi et al., 2015) reported on the differential impact of message framing between non-problem (recreational) and problem gamblers. Outcomes The outcomes reported by the studies (see suppl. file S4) could be categorised into three broad groups: exposure outcomes (e.g. message recall, message comprehension, beliefs about message effectiveness, engagement with message), cognitive outcomes (e.g. knowl- edge/awareness, attitudes, and beliefs about risks and harms associated with gambling, and of availability of support services), and intentions/behavioural outcomes (e.g. gam- bling consumption, seeking help, supporting someone affected by gambling). The use of an existing psychological theory was reported in only three studies. Two studies (Munoz et al., 2010; Muñoz et al., 2013) used the elaboration likelihood model (Cacioppo & Petty, 1979) and the protection motivation theory (Rogers, 1975) to study the effects of gambling risk warning messages, and one study (Orazi et al., 2015) used the construal level theory (Trope & Liberman, 2010) to investigate the impact of framing of messages on outcomes. Methodological Quality of the Studies The authors acknowledged a range of limitations including self-selection bias and non-rep- resentativeness of the sample, a reliance on self-reported measures and unreliable scales, a lack of ecological validity, incomplete data and/or loss of data (attrition bias), challenges 369 International Journal of Mental Health and Addiction (2024) 24:347–380 with study design and procedures, and financial reward for participation. Only two studies (Newall et al., 2020a, 2020b) reported objectively measuring understanding of messages. Using the JBI tools, the methodological quality of the studies was assessed as ‘high’ for all the quasi-experimental and cross-sectional analytical studies, and the only qualitative study (Table 2). For the randomised controlled experimental studies, the methodological quality was assessed as high in one study, medium in eight studies, and low in two studies. The full quality appraisal of the individual studies is presented in suppl. file S5. The assess- ment showed that some studies that used quasi-experimental designs did not use an inde- pendent control group. Among those that deployed randomised controlled experiments, some studies did not report details of randomisation and allocation procedures (potential for selection bias) and did not use blinding procedures for personnel administering the test procedures (potential for performance bias). None of the randomised controlled experi- mental studies reported blinding of participants or whether blinding procedures were used for outcome assessors (potential for detection bias). Synthesis of Results Key findings of the included studies are presented in Table 2. Messaging Aimed at the General Population Evidence about messaging aimed at the general population for the prevention of GRH is currently limited. The available evidence indicates that messaging campaigns can increase awareness of gambling harms but their impact on people’s gambling is not clear. Seven studies reported the effects of a population-level messaging intervention. Of these, six stud- ies used self-reported surveys and one used qualitative methods (specifically interviews) to collect data. Four of these studies evaluated messaging delivered as part of a mass media or social marketing campaign, including two studies that examined the impact of the second (Hall & Dickinson, 2009) and third (Magill et al., 2013) stages of the government-funded New Zealand Health Sponsorship Council’s Kiwi Lives campaign that was launched in 2007 and is ongoing. The findings demonstrated that mass media campaigns via television can be seen as relevant and credible, positively portray help-seeking, and increase subjective awareness of GRH (Hall & Dickinson, 2009; Magill et al., 2013). However, they had a somewhat limited impact on subsequent reported actions (e.g. 7% looked or searched for more information (Hall & Dickinson, 2009), 6% reduced gambling (Magill et  al., 2013), and 5% stopped gambling (Magill et al., 2013)). Although these percentages are low, the impact on those involved and their families may have been significant. Indeed, almost 40% of respond- ents who had experienced or been exposed to harmful gambling and had seen the adver- tisements reported that they had taken action (Magill et al., 2013). In contrast, a one-off campaign via radio, newspaper, and billboards had low exposure (8%) and no evidence of impact on awareness of risks, harms, or availability of help resources (Najavits et al., 2003). The review found that approaches such as posters (Diehr et  al., 2018) and brochures (Ladouceur et al., 2000) created as part of a public campaign can raise awareness of prob- lem gambling harms, at-risk behaviours, and availability of support services; however, they lack efficacy at promoting help-seeking behaviour in people who identify as problem gamblers (Calderwood & Wellington, 2015). The review’s only qualitative study (Thomas 370 International Journal of Mental Health and Addiction (2024) 24:347–380 et al., 2012) identified three key themes from participants’ narratives: campaigns focus on personal responsibility or target those with severe gambling problems; campaign messages are undermined by the overwhelming volume of positive messages from the industry; and personal responsibility-themed messages reinforce perceptions of stigma and act as a bar- rier to help-seeking. Gambling Harm Prevention/Reduction Messages The evidence (derived mainly from experimental laboratory-based research) shows that existing industry-sponsored ‘safer’ gambling messages do not change gambling behav- iours. Independent evaluations of UK ‘safer’ gambling messages, e.g. ‘When the fun stops, stop’ (the most prevalent industry-sponsored message in the UK from 2014 until 2021) (P Newall et al., 2019; P. Newall et al., 2022), and the currently used message ‘Take time to think’ (P Newall et  al., 2023a, 2023b) have demonstrated that these messages do not have protective effects on gambling behaviours. Indeed, participants who saw the message ‘when the fun stops, stop’ were 6% more likely to gamble all their money compared with participants who were not shown this message. A survey evaluation (Mouneyrac et  al., 2017) of 14 European GRH prevention mes- sages (including seven industry-sponsored messages) reported that messages informing about gambling risks and correcting erroneous beliefs (e.g. odds of winning) are judged by respondents as having greater communicative and preventive value than messages pro- moting ‘responsible gambling’ (these were judged as ambiguous). One study (Orazi et al., 2015) that examined the interplay between the nature and framing of consequences of gambling in messaging found that compared to material consequences (financial losses), messages highlighting social consequences (social exclusion, family disruption) were more effective in reducing the tendency to gamble; further, this differential impact of social ver- sus material consequences was stronger among problem gamblers than non-problem gam- blers, and when the consequences were presented as losses (versus as gains). Gambling Product Risk Warning Labels The evidence related to gambling risk warning labels (derived from experimental studies) suggests that the way warning messages are presented, and the wording of message con- tent, can influence players’ understanding of the warning and their beliefs (about financial costs and chances of winning) and decision-making. Brief exposure to warning messages demonstrated increased knowledge about gambling risks and reduction in erroneous beliefs (odds of winning) in college students who gamble (Steenbergh et al., 2004). Another study found that college students often failed to identify or fully comprehend warning messages on lottery tickets (Horn et  al., 2021). Three studies reported the effects of video lottery terminal (VLT) warning labels. Higher threat warnings (resulting from fear appeals of the labels) and the medical/government agency source of warnings (as opposed to the gam- bling industry source) were found to lead to change in attitudes (significantly and posi- tively), and intentions to comply with the warnings in a study in which 37% of the study participants were identified as a ‘problem gambler’ (Munoz et  al., 2010). Another study (Muñoz et  al., 2013) reported that graphic content (a cartoon showing a monster eating a gambler) combined with a family disruption warning message was more effective for changing attitudes and compliance with the warning than text-only content combined with financial disruption content. The display of warning banners prior to playing (informing 371 International Journal of Mental Health and Addiction (2024) 24:347–380 consumers of the randomness of pay-outs) on VLT machines for a 2-week period was asso- ciated with significantly decreased self-reported gambling play by participants (irrespec- tive of problem gambling status), and for those assessed as problem gamblers (50% of the subject pool), a significant reduction of erroneous beliefs (e.g. having control over wins and losses) (Gallagher et al., 2011). Four studies reported on the effects of framing of risk warning labels on gambling behaviours, risk perception, and perceived chances of winning. One study (Walker et al., 2019) found that judgments (about maximising chances of winning) in scratch card gam- bling were improved by presenting the payback percentage information (representing the true monetary value of a card) in a graphical format as opposed to a numerical format. Restating the risk information (odds of winning) from the currently prevalent ‘return to player’ format (e.g. this game has an average payout of 90%) to a ‘house-edge’ format (e.g. this game keeps 10% of all money bet on average) led to lower perceived chances of win- ning and better understanding of product risk (Newall et al., 2020a); however, presenting this information as either percentages (e.g. this game keeps 0.5%/7.5%/15% of all money bet on average) or currency units (e.g. this game keeps 50p/£7.50/£15 for every £100 bet on average) did not lead to any significant difference in risk perception (Newall et al., 2021). Adding a statement about the volatility of gambling (explaining that payback percentages are long-run statistical averages, which may not be experienced in any short period of gam- bling) to the house-edge format warning message was found to have a cumulative effect on reducing players’ perceived chances of winning, thereby improving risk perception (Newall et al., 2020b). Discussion This review synthesises the published evidence for the effectiveness of population-level public health gambling messaging focused on the primary prevention of GRH. Informed by the GRH reduction messaging literature, the interventions were categorised into three groups: whole-population level messaging (e.g. mass media campaigns), harm preven- tion/reduction messaging, and product risk warning labels. The outcomes most frequently reported by the studies were those related to message exposure (e.g. message recall, per- ceived relevance, and perceived effectiveness of message). Few studies reported social cog- nitive outcomes, such as knowledge and awareness of risks and harms of gambling. Also, few studies reported on changes in intentions to gamble or intensity of gambling activi- ties. The outcomes most frequently reported by experimental studies were beliefs about chances of winning and behavioural intentions just prior to or during a gambling session. Therefore, it is fair to conclude that the evidence concerning effective harm reduction is extremely limited. There was, however, evidence indicating that gambling messaging can impact some of the determinants of gambling behaviour. For example, we identified some evidence that messages eliciting negative emotions (fear and threat appeals), and loss-framed messages may be effective in changing attitudes, complying with warnings, and reduc- ing the propensity to gamble especially in individuals who are identified as having a gambling problem. The behavioural science literature suggests that negative emo- tion and fear appeals are likely to be effective when they also maintain perceptions of self-efficacy (Ruiter et al., 2014). However, gambling is associated with perceived social stigma, feelings of shame, and low levels of help-seeking (Hing et  al., 2016). 372 International Journal of Mental Health and Addiction (2024) 24:347–380 The evidence presented by the qualitative study included in this review (Thomas et al., 2012) and supported by evidence from exploratory qualitative research in GRH litera- ture (Brown & Russell, 2020a; Davies et  al., 2022; Gainsbury et  al., 2018) strongly suggests that messages that provoke negative emotions (shame, guilt) and have a focus on personal responsibility may lead to message avoidance and fail to produce posi- tive behavioural change. Emphasising personal responsibility for a stigmatised health condition may result in unintended consequences and/or contribute to public stigma. For instance, messages promoting responsible drinking designed to stimulate nega- tive emotions can have the effect of increasing drinking intentions in young people (Agrawal & Duhachek, 2010). Also, hard-hitting anti-tobacco campaigns are likely to be effective in changing attitudes and intentions toward smoking and decrease smok- ing rates, but they have the unintended consequences of stigmatising those affected with smoking-related illnesses (Riley et  al., 2017). The evidence from several stud- ies included in this review indicates that messages that have an appropriate tone, are authentic and relatable, and appear to be personally relevant are likely to be more effective. We found very limited empirical information about the effectiveness of gambling messaging targeting the general population. This was unsurprising because research on whole population-level messaging as part of a public health approach to gambling has only recently begun to emerge. Although public health principles to approach gam- bling and a harm reduction strategy are incorporated at the policy level in the UK and several other countries (e.g. Canada, Australia, Sweden), currently, New Zealand is the only country with an independent (government-funded) population-level public health gambling messaging in place (Price et al., 2021). The limited evidence we found sup- ports the learning from other public health areas that campaigns that are well-funded and long-term (more sustained and greater intensity) and independent of the industry are more likely to be effective (Stead et al., 2019). We also found that there is no strong evidence supporting the current format of industry-sponsored ‘safer’ gambling messages (i.e. messages that are intended to reduce the potential for GRH). Moreover, there is evidence that messages promoting ‘safer or responsible gambling’ practices may be perceived to be ambiguous, whereas messages describing the risks of gambling and messages and correcting erroneous beliefs are likely to be perceived to be of higher preventive value. Similar findings are reported from research on the impact of ‘personal responsibility’ framing of messaging used by the tobacco and alcohol industries. For example, industry-sponsored ‘Think, Don’t Smoke’ campaign promoted and improved the industry’s image and interests, rather than changing smoking behaviours (Henriksen et al., 2006). Likewise, responsi- ble drinking messages developed by the alcohol industry are perceived as ambiguous by audiences and are ineffective in changing behaviour (Smith et al., 2006). Lastly, when considering warning labels, again the existing empirical evidence is very limited. One study suggested that warning messages that are sourced from a med- ical or government agency (in contrast to a gambling provider source) may be more effective in shifting attitudes and intentions (Munoz et al., 2010). Also, a focus on con- sequences for the family is likely to be more effective in changing attitudes and beliefs than a focus on financial consequences (Muñoz et  al., 2013; Orazi et  al., 2015). The review also identified an emerging body of research focused on improving current risk warning messages that can be applied to a wide range of gambling products to enable consumers to make more informed judgments. 373 International Journal of Mental Health and Addiction (2024) 24:347–380 Gaps in Knowledge Our review identified several important knowledge gaps. First, there is a lack of knowl- edge about how GRH reduction messages impact on different groups of people. This is an important knowledge gap because there is evidence from exploratory research (Gainsbury et al., 2018; Messerlian & Derevensky, 2006; Pitt et al., 2022) that people exhibit different preferences and responses to archetypes of gambling messages depending on factors such as their age and level of gambling participation. Demographic details concerning popula- tions recruited to the studies featured were often limited (a limitation of the evidence base itself), but we identified a lack of evidence from samples of young people, those already experiencing GRH, and people who identify as members of ethnic and religious minority groups. Second, there is limited knowledge about the extent to which gambling messaging results in people taking positive actions (e.g. reducing gambling, engaging with support services). Third, the review did not identify any messaging interventions addressing public health priority concerns for GRH reduction such as gambling-associated stigma (Brown & Russell, 2020b), protection of young people from GRH (Thomas et al., 2023), and GRH experienced by family and social network members of someone with a gambling problem (McCarthy et al., 2023). These areas are ripe for further research. Strengths and Limitations To our knowledge, this is the first systematic review to report on the effectiveness of a broad range of gambling messaging interventions that are regarded as potentially important components of a public health approach to the prevention of GRH. The review is informed by guidance on the conduct of narrative synthesis in systematic reviews (Popay et  al., 2006) and reported in line with PRISMA (Page et al., 2021). Screening was undertaken in duplicate, and critical appraisal and data extraction were undertaken by one reviewer and checked in full by a second reviewer. We did not limit studies by country/setting and study designs, and a wide range of outcomes were sought, thus providing a rich and comprehen- sive dataset. Several limitations of this research may be acknowledged. Given the countries of ori- gin of the included studies, the findings of this review are likely to be relevant only to high-income countries. Limiting the searches to English language publications may have excluded relevant studies from countries with different cultural and socioeconomic profiles that may have different patterns of gambling. Additionally, limiting the searches for studies involving recipients 11 years old or more may have excluded relevant studies addressing harm reduction for children younger than 11 years old. We included all studies that met the inclusion criteria irrespective of the assessment of their quality. As highlighted ear- lier, the data presented are subject to different sources of bias, notably selection bias and social desirability bias. The evidence presented for the different categories of messaging interventions is derived from a limited number of primary studies. The heterogeneity of the included studies (specifically, study design, intervention aims, and reported outcomes), as well as the lack of consistency of outcome findings across the different studies, made it difficult to combine and analyse data from different studies conducted on similar research topics. Finally, we recognise that operationalising a definition of gambling-related public health messaging is challenging and may be approached in different ways. Here, we offer and justify one approach, and invite further dialogue and constructive challenge. 374 International Journal of Mental Health and Addiction (2024) 24:347–380 Implications for Research and Policy The review findings confirm the opinions expressed in recent gambling messaging litera- ture that industry-led messaging does not facilitate a public health approach to gambling harm prevention (Marko et al., 2023). There is an urgent need to develop and test independ- ent public health messaging to raise awareness of risks and harms of gambling and reduce stigma associated with harmful gambling, and messaging for people affected by someone else’s gambling. The literature recommends that GRH prevention messaging should take a targeted approach, similar to the highly targeted approach used by the gambling industry (Davies et al., 2022; Gainsbury et al., 2018). This highlights the need for research on how GRH prevention or reduction messages impact different groups of people. The limited nature of the evidence from the included studies in terms of both quality and quantity makes it difficult to make clear recommendations for audience targeting and appropriate framing of language for public health gambling messages. However, some rec- ommendations in relation to potentially effective interventions can be made. Messaging campaigns that are long-term and supported by policies that enable and support behav- iour change can generate desired outcomes. Relevant topics for independent public health gambling message development are education about safer gambling practices, correcting erroneous beliefs, and improving conscious decision-making at the point of engagement, norm-based messages, and positive emotional messages. Messages should be tailored to different audience segments (e.g. according to severity of the gambling behaviour). Pub- lic health practitioners and other stakeholders should anticipate whether there may be any unforeseen or unintended consequences (e.g. stigma or stereotyping) associated with mes- saging campaigns. Conclusion The review has highlighted that the existing evidence about the effectiveness of public health messaging for primary prevention of gambling harms is very limited but gener- ally indicates that currently used messages are ineffective in changing behaviour, although they can raise awareness of gambling harms and safer gambling practices. Providing clear information about long-term risks and harms along with appropriate tone is more likely to encourage reduction in gambling. Improvements are needed to the formats and presenta- tion of currently used product risk warning labels. The review identified important knowl- edge and research gaps. An area for future work is engagement with members of the public and other stakeholders in designing messaging interventions that are likely to be effective, and importantly, not have unintended negative consequences such as increasing stigma. Supplementary Information  The online version contains supplementary material available at https://​doi.​ org/​10.​1007/​s11469-​024-​01414-w. Acknowledgements  The research team thanks the following for their support with this research: Lesley Hall, Manager of the NIHR Policy Research Unit (PRU) in Behavioural and Social Sciences for project oversight. Author Contribution  Conceptualisation: Emily J. Oliver, Michael P. Kelly, Ivo Vlaev, Fiona R. Beyer, Katie Thomson, Akvile Stoniute, Devashish Ray; formal analysis and investigation: Devashish Ray, Katie Thom- son, Fiona R. Beyer; Akvile Stoniute, Oluwatomi Arisa, Oleta Williams; writing—original draft: Devashish Ray, Katie Thomson, Oleta Williams; writing—review and editing: Michael P. Kelly, Emily J. Oliver, Katie 375 https://doi.org/10.1007/s11469-024-01414-w https://doi.org/10.1007/s11469-024-01414-w International Journal of Mental Health and Addiction (2024) 24:347–380 Thomson, Fiona R. Beyer, Ivo Vlaev, Devashish Ray; funding acquisition: Emily J. Oliver, Michael P. Kelly; supervision: Emily J. Oliver, Michael P. Kelly. All listed authors have approved the manuscript before submission, including the names and order of authors. Funding  This study was funded by the National Institute for Health and Care Research (NIHR) (Policy Research Program (Policy Research Unit in Behavioural Science PR-PRU1217-20501)). The views expressed are those of the author(s) and do not necessarily represent the official views of the NIHR or the Department of Health and Social Care. Data Availability  The data extracted from the included studies are available upon request to the correspond- ing author (devashish.ray@newcastle.ac.uk). Declarations  Ethics Approval  Ethics approval for this study was not necessary. Conflict of Interest  The authors declare no competing interests. Open Access  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Com- mons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. 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Journal of Gambling Studies, 35(3), 945– 968. https://​doi.​org/​10.​1007/​s10899-​019-​09860-1 Publisher’s Note  Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 380 https://doi.org/10.1002/9781119536604.ch2 https://doi.org/10.1111/hex.12018 https://doi.org/10.1093/heapro/daac194 https://doi.org/10.1037/a0018963 https://doi.org/10.1016/S0140-6736(10)60809-4 https://doi.org/10.1007/s10899-019-09860-1 Effectiveness of Public Messaging Within the Gambling Domain: A Systematic Review Abstract Methods Inclusion Criteria Exclusion Criteria Search Strategy Results Results of the Searches Included Studies Outcomes Methodological Quality of the Studies Synthesis of Results Messaging Aimed at the General Population Gambling Harm PreventionReduction Messages Gambling Product Risk Warning Labels Discussion Gaps in Knowledge Strengths and Limitations Implications for Research and Policy Conclusion Acknowledgements References