Another way to phrase this question would be: "What type of incentive and/or motivator would be necessary to persuade a person to undertake a beneficial, yet somewhat unpleasant, activity?

Contingency Management (ie. payment for behavior change) is an established psychosocial intervention with a strong evidence base to support its utilization across a wide variety of health behaviors. We are currently involved in a programme of research to explore its effectiveness at promoting health behaviors and in maintaining abstinence from drugs.

From the UK NICE website:

"“Drug services should introduce contingency management programmes… to reduce illicit drug use and/or promote engagement with services for people receiving methadone maintenance treatment. … Where possible, implementation in the NHS should draw on the experience so far (albeit limited) of contingency management in the NHS and on the experience of agencies such as the National Treatment Agency for Substance Misuse (NTA) in the implementation of service developments in drug misuse.”[ii]

In 2009 the NTA conducted a demonstration programme that looked at the implementation of CM in selected drug treatment services. Since the programme concluded, CM for drug use has been included as an intervention in the NDTMS modality codes. Meanwhile, the expertise of the pilot sites has been placed at the disposal of the ConMan programme of five linked research studies that started in 2009 and runs to 2014.

The aim of the study is to develop a UK evidence base for contingency management in addiction treatment. The programme, which is funded by a National Institute for Health Research (NIHR) Programme Grant, is being led by the South London & Maudsley (SLaM) NHS Foundation Trust, but is a collaborative venture by investigators based at three London NHS trusts and universities."

In my opinion, it’s good to have a contingency/situational approach to this phenomenon. In economic terms, different people respond to different amounts of money as the marginal utility of money decreases. For example considering $ 1000 prize for smoking cessation in lower income population can be effective than in higher income population. So In practice, this method may just be applicable to some degree, otherwise we must expend all the Gross Domestic Product (GDP) in providing financial incentives for wealthy people!

For developing countries (eg. PNG) especially in the rural populations and the settlements, the effectiveness of such intervention will be very costly and the provider may not have the financial resource to sustain such activity for a continuous period. An additional high cost would include logistics ( taking into account the remoteness). I support Eirini Agapidaki. Lets opt for the non financial incentives.

You may wish to read this earlier review of the literature by The King's Fund http://www.kingsfund.org.uk/sites/files/kf/field/field_document/paying-the-patient-kicking-bad-habits-supporting-paper-karen-jochelson.pdf. It shows that financial centimes can have an effect but it is often short lived and is most effective for simple actions eg attending a weight watchers meeting and less effective for changing complex behaviours

Not very effective. As a short term reward there may be some promising results initially but they won't last.

The real reward is experienced internally that produces a lasting change. External rewards are generally short term primarily because they are not for the self.. but for someone else. Simply put.