Reward appears as result of changes in Discomfort level.
Reward = old Discomfort level Ė new Discomfort level
If Discomfort level was decreased by goalís event impact then reward is positive.
If Discomfort level was increased by goalís event impact then reward is negative.
Reward is distributed over cause concepts which are responsible for the goal satisfaction.
Related cause-effect relations could be also updated.
Reward isnít affected by fading.