Drives and desires can be described as a deficiency or need that activates behavior that is aimed at a goal or an incentive. These are thought to originate within the individual and may not require external stimuli to encourage the behavior. Basic drives could be sparked by deficiencies such as hunger, which motivates a person to seek food; whereas more subtle drives might be the desire for praise and approval, which motivates a person to behave in a manner pleasing to others.
By contrast, the role of extrinsic rewards and stimuli can be seen in the example of training animals by giving them treats when they perform a trick correctly. The treat motivates the animals to perform the trick consistently, even later when the treat is removed from the process.
Intrinsic motivation is the drive for which people engage in an activity, without obvious external incentives, such as a hobby. Intrinsic motivation has been studied by educational psychologists since the 1970s, and numerous studies have found it to be associated with high educational achievement and enjoyment by students.