The evidence.
The published research behind the Uservox page, grouped by what each study shows. Each title links to the study.
What people think and believe
Nisbett and Wilson, “Telling more than we can know”, Psychological Review, 1977. Greenwald and Banaji, “Implicit social cognition”, Psychological Review, 1995. Charlesworth and Banaji, “Patterns of implicit and explicit attitudes II”, American Psychologist, 2021. Hofmann and colleagues, “A meta-analysis on the correlation between the Implicit Association Test and explicit self-report measures”, Personality and Social Psychology Bulletin, 2005: 126 studies, mean correlation 0.24.
What people say
Krumpal, “Determinants of social desirability bias in sensitive surveys”, Quality & Quantity, 2013. Larson, “Controlling social desirability bias”, International Journal of Market Research, 2019. Tourangeau and Yan, “Sensitive questions in surveys”, Psychological Bulletin, 2007. Murphy and colleagues, “A meta-analysis of hypothetical bias in stated preference valuation”, Environmental and Resource Economics, 2005: median ratio of stated to actual willingness to pay 1.35; List and Gallet, 2001 found factors up to three.
What people do
Our compilation. Eight studies that asked people whether they would do something, then checked. The share of those who said they would who did: Sheeran, “Intention-behavior relations”, European Review of Social Psychology, 2002, 422 studies and 82,107 people, mostly health: a median 53 in a hundred; Rhodes and de Bruijn, “How big is the physical activity intention-behaviour gap?”, British Journal of Health Psychology, 2013, ten studies, 3,899 people: 54 in a hundred (42 per cent of the sample were intenders who acted, 36 per cent intenders who did not); DellaVigna and Malmendier, “Paying not to go to the gym”, American Economic Review, 2006, 7,752 members: forecast 9.5 visits a month, actual 4.17, so 44 in a hundred of the promised visits; Harris, Maurer and Lurie, “Do people who intend to get a flu shot actually get one?”, Journal of General Internal Medicine, 2009, 1,527 adults: just over half; Rogers and Aida, “Vote self-prediction hardly predicts who will vote”, American Politics Research, 2014, 29,403 people across three elections: fewer than half of those who said they would vote did; White, Hardisty and Habib, “The elusive green consumer”, Harvard Business Review, 2019: 65 per cent say they want to buy from sustainable brands, 26 per cent do, so 40 in a hundred; Ganczak and colleagues, “Does vaccinating against influenza in a given epidemic season have an impact on vaccination in the next season?”, International Journal of Environmental Research and Public Health, 2022, a Polish follow-up study: of patients willing to have the next season’s flu vaccine, 31.9 per cent had it; Cowe and Williams, Who are the ethical consumers?, Co-operative Bank, 2000, the “30:3” gap, 30 per cent say and 3 per cent buy, so 10 in a hundred, as reported in Bray, Johns and Kilburn, Journal of Business Ethics, 2011. Range 10 to 54; counting the two “about half” results as 50, the median of the eight is 47. Background: Webb and Sheeran, “Does changing behavioral intentions engender behavior change?”, Psychological Bulletin, 2006: across 47 experiments, a medium-to-large change in intention (0.66) produced a small-to-medium change in behaviour (0.36). Sheeran and Webb, “The intention-behavior gap”, Social and Personality Psychology Compass, 2016. Conner and Norman, “Understanding the intention-behavior gap”, Frontiers in Psychology, 2022. Stirratt and colleagues, “Self-report measures of medication adherence behavior”, Translational Behavioral Medicine, 2015.
Between people and systems
Fogg, “A behavior model for persuasive design”, Persuasive ’09, 2009: behaviour happens when motivation, ability and a prompt meet. Michie, van Stralen and West, “The behaviour change wheel”, Implementation Science, 2011. DellaVigna and Linos, “RCTs to scale: comprehensive evidence from two nudge units”, Econometrica, 2022. Sheeran and Orbell, “Using implementation intentions to increase attendance for cervical cancer screening”, Health Psychology, 2000: attendance 69 per cent without a when-and-where plan, 92 per cent with one. Gollwitzer and Sheeran, “Implementation intentions and goal achievement: a meta-analysis”, Advances in Experimental Social Psychology, 2006: 94 tests, effect size 0.65.