title: The effect of glass shape on alcohol consumption in a naturalistic setting: a feasibility study.
abstract: BACKGROUND
  Alcohol-related harms are a major public health concern, and population-level interventions are needed to reduce excessive alcohol consumption. Glass shape is an easily modifiable target for public health intervention. Laboratory findings show beer is consumed slower from a straight glass compared to a curved glass, but these findings have not been replicated in a naturalistic setting. The purpose of this study is to investigate the feasibility of conducting a randomised controlled trial investigating the effect of glass shape on alcohol consumption in public houses.
  
  
  METHODS
  Straight and curved half-pint and pint glasses were delivered to three public houses over two weekends. Glass type was counterbalanced over the two weekends and between the public houses. Monetary takings were recorded as an indirect measure of consumption.
  
  
  RESULTS
  Replacing stocks of glassware in public houses was feasible and can be enacted in a short space of time. One landlord found the study too disruptive, possibly due to a laborious exchange of glassware and complaints about the new glassware from some customers. One public house's dishwasher could not accommodate the supplied curved full-pint glasses. Obtaining monetary takings from public house staff was a feasible and efficient way of measuring consumption, although reporting absolute amounts may be commercially sensitive. Monetary takings were reduced by 24 % (95 % confidence interval 77 % reduction to 29 % increase) when straight glasses were used compared to curved glasses.
  
  
  CONCLUSIONS
  This study shows that it is feasible to carry out a trial investigating glass shape in a naturalistic environment, although a number of challenges were encountered. Brewery owners and landlords are willing to engage with public health research in settings where alcohol is consumed, such as public houses. Good communication with stakeholders was vital to acquire good data, and highlighting the potential commercial benefits of participating was vital to the study's success. A full scale evaluation of the effects of glass shape on alcohol consumption could inform local and national policy.
authors.affiliation: MRC Integrative Epidemiology Unit (IEU), University of Bristol, Bristol, UK ; UK Centre for Tobacco and Alcohol Studies, School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Troy
authors.affiliation: MRC Integrative Epidemiology Unit (IEU), University of Bristol, Bristol, UK ; UK Centre for Tobacco and Alcohol Studies, School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK.
authors.forename: Olivia M
authors.initials: OM
authors.lastname: Maynard
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Hickman
authors.affiliation: MRC Integrative Epidemiology Unit (IEU), University of Bristol, Bristol, UK ; UK Centre for Tobacco and Alcohol Studies, School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK.
authors.forename: Angela S
authors.initials: AS
authors.lastname: Attwood
authors.affiliation: MRC Integrative Epidemiology Unit (IEU), University of Bristol, Bristol, UK ; UK Centre for Tobacco and Alcohol Studies, School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK.
authors.forename: Marcus R
authors.initials: MR
authors.lastname: Munafò
keywords: Alcohol; Choice architecture; Glass shape; Harm reduction