One review  investigated the effectiveness of incentive schemes to improve health and other behaviours:
Analysis of the studies reviewed showed that single or dual component incentive schemes are effective in encouraging positive health behaviours where a simple or single action is required, rather than a sustained health behaviour change. The Child Health Programme as described in the White Paper Choosing Health covers screening and immunisations which are single event health behaviours shown in our review as likely to benefit from the use of incentives to encourage uptake.
The government target to reduce health inequalities as measured by infant mortality by 2010 focuses on interventions to improve services and support for pregnant women, new mothers and their babies. The highest rate of infant mortality is in children born to teenage mothers. We found non-financial incentives to be effective in encouraging teenage mothers to attend an early post-natal health clinic.
The interventions were also shown to be effective in reducing smoking behaviours in the context of school-based competitions. These findings are based on a small number of studies, none of which were conducted in the UK, but they are consistent with other systematic review evidence.
The incentives were mostly financial or gifts/tokens.
A subsequent scoping review  found 27 potentially* systematic reviews relating to the use of incentives to reduce smoking behaviours and to encourage healthy eating and obesity reduction. The review found: eight primary studies on smoking in people with low socio-economic status, but no systematic reviews; 13 primary studies and just one potentially systematic review on smoking in pregnancy; and 16 primary studies and just one systematic review on obesity and weight loss. It was concluded that further systematic reviews are needed in these areas.
The review found no evidence that single or dual component incentive schemes are effective in improving either the levels of effort applied to educational tests or attendance levels in school.
Overall single or dual component incentive schemes do not appear to offer policy-makers or practitioners a simple route to ensuring general positive behaviour changes in young people. However, they may be useful in particular settings and for particular groups.
An earlier study  describes 37 schemes using incentives aimed at promoting a range of positive behaviours in young people. The schemes were mostly based in the UK, with some from the USA, Australia and New Zealand. Two were international in scope. Fifteen of the schemes targeted young people at risk; eleven provided direct cash incentives; and the others used a variety of different material incentives.
1. A summary of ongoing activity in the use of incentive schemes to encourage positive behaviours in young people (2005)
2. A systematic review of the evidence for incentive schemes to encourage positive health and other social behaviours in young people (2006)
3. Incentives to improve smoking, physical activity, dietary and weight management behaviours: a scoping review of the research evidence (2009)
*The scoping review only looked at abstracts, so could not confirm that the systematic reviews actually used appropriate methods.