This is an operant conditioning principle in which an organism is reinforced every single time that organism provides the appropriate operant response. For example, you, as a researcher, might present a food pellet every time the rat presses the lever. One of the biggest dangers when using this type of reinforcement is saturation (the organism basically gets full - you keep feeding it and it no longer wants the reinforcement because it is stuffed), so the idea that giving reinforcement all the time is the best way to teach/learn is not necessarily true.
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