This theory was developed by the behaviourist school of psychology, notably by B.F. Skinner earlier this century (Laird 1985, Burns 1995). Skinner believed that behaviour is a function of its consequences. The learner will repeat the desired behaviour if positive reinforcement (a pleasant consequence) follows the behaviour.
Positive reinforcement, or ‘rewards’ can include verbal reinforcement such as ‘That’s great’ or ‘You’re certainly on the right track’ through to more tangible rewards such as a certificate at the end of the course or promotion to a higher level in an organisation.
I’m not sure how much of this theory could be used in my project as it isn’t directly related, but I did find it interesting how positive reinforcement can be used to change behaviours. This could be adopted by communication design to encourage and enforce positive behaviour change.