New York, April 3 (IANS): A team of US researchers has found that monetary rewards for healthy behaviour can pay off both in the pocketbook and in positive psychological factors like internal motivation to eat fruits and vegetables, according to a study.

The study, which encouraged daily consumption of fruits and vegetables in exchange for payment, not only showed monetary incentives worked, but that participants increased their internal motivation to eat fruits and vegetables over time.

Increased fruit and vegetable consumption by participants is linked to more positive attitudes and self efficacy - the confidence in one's own ability to succeed.

"While programs involving monetary incentives to encourage healthy behaviour have become more popular in recent years, the evidence has been mixed as to how they can be most effective and how participants fare once the incentives stop," said lead author Casey Gardiner from University of Colorado Boulder in US.

"Some psychological research and theories suggest that if individuals have external motivations like payment to perform tasks, their internal, or intrinsic motivation can be undermined," said Gardiner of the psychology and neuroscience department.

The findings showed that participants who were assigned to receive payment for eating fruits and vegetables were still consuming more than usual two weeks after the study ended.

In the study, 60 adults were randomly assigned to three different groups.

Individuals in one group received $1 for every serving of fruits and vegetables they reported consuming daily over a three-week period.

People in the second group accrued $1 for every serving of fruits and vegetables eaten, with the lump sum money delivered at the end of the study.

Participants in the third group reported their fruit and vegetable consumption daily for three weeks with no incentives.

The participants who received daily monetary incentives had the greatest increase in their fruit and vegetable consumption.

"This finding highlights the importance of incentive design in health programs and differences in the timing or type of incentive can alter their effectiveness," Gardiner stated.

We essentially showed that incentives may be able to help people to 'jumpstart' behaviour changes, but that changes in key psychological factors help people maintain the behaviour when the incentives end, Gardiner noted.