Continuous levels of hazardous alcohol consumption (i.e., 14 or more units per week) is one of the leading risk factors of ill health and early mortality, contributing to around 9,809 deaths a year in the UK. The aim of the present research is to test the effect of helping people to reward themselves when they have successfully reduced/abstained from their previous levels of alcohol consumption. Each participant will be randomly allocated to one of two conditions. The trial requires 128 participants to perform a fully powered statistical analysis. The two conditions include: (1) a control condition (asked to form a plan to reduce/abstain from alcohol consumption), or (2) a weekly self-incentivising condition (asked to reward themselves at the end of each week that they have successfully reduced/abstained their previous levels of alcohol consumption). The main outcome measure will be units of alcohol consumed/not consumed, which will be self-reported at 1-week and 1-month follow-up time points.

The research aims to test the role of self-incentivising implementation intentions for reductions/abstinence of alcohol consumption among people aged 18 and over, residing in the UK, and consuming 14 units of more of alcohol at the start of the study. The effectiveness of self-incentives has been successfully seen previously within health behaviour change, has not been tested in reduction/abstinence of alcohol consumption. Therefore, this research will build on what is known about the effectiveness of self-incentives used for increasing fruit and vegetable consumption, and smoking cessation.

This study is a randomised controlled trial with the between participants factor of condition which has two levels:

1. Control (plan) or 2. Weekly self-incentivising implementation intention.

The within participants' factor will be time which has three levels:

Baseline (T1) Follow-up (T2) (1-week following baseline) Follow-up (T3) (1-month following baseline)

An ethical concern is that participants in the control condition may struggle more to reduce/abstain from alcohol consumption as they will not have the additional benefits of being within an experimental condition which uses self-incentives to aid their attempt. A control condition is needed to monitor if changes to alcohol consumption is due to the use of self-incentives or another behaviour change technique.

The recruitment process will recruit participants to complete an online questionnaire (via Qualtrics), from Prolific. Prolific is an online recruitment platform, which allows screeners to be set (e.g., age, residency, consumption level) prior to contacting potential participants. Prolific then contacts the participants to which the screeners apply, and the participants can decide if they would like to take part. The researcher can then set restrictions to only allow completion of the follow-up questionnaires, based on those participants who completed the online questionnaire at baseline.

All participants who are able to provide informed consent, are over the age of 18 years old, resident in the UK (due to discrepancies in the safe recommended alcohol consumption rates across countries), are eligible to take part in the study. Unfortunately, the study does not cater for people who cannot understand English at the present time, although this will be monitored for amendments in future studies.

The participant information sheet included prior to the online questionnaire includes details about the study, costs and benefits of taking part in the study, and the right to consent and withdraw at any point throughout the study. There are no risks involved in taking part in the study. Participants are reimbursed via Prolific based on the expected time to complete each questionnaire (i.e., £3.55 per questionnaire completed, which equates to more than the current UK living wage). There is a minimal burden in time taken to complete the questionnaires, which should take no longer than 15 minutes per time point, though this time estimation is considered generous.

In terms of confidentiality, participants will not provide any identifier other than their Prolific ID. This ensures that no identifying information is available to the research team, but that the participant can be added to the screener for completion of the baseline questionnaires, and that all questionnaires (baseline, 1-week follow-up, and 1-month follow-up) can be matched.

There are no conflicts of interest. Participants are provided with contact details of the research team, should they like to contact for a summary of the results.

Inclusion Criteria:

• Aged 18 years or over
• Able to understand written English
• Competent to provide informed consent
• Residing in the UK
• Regularly consuming 14 units of alcohol or more at baseline

Exclusion Criteria:

• Note aged 18 years old or over
• Not able to understand written English
• Not competent to provide informed consent
• Not residing in the UK
• Not regularly consuming 14 units of alcohol or more at baseline

Data may be shared if this complies with ethical guidelines