Primary reinforcement

Primary reinforcement is a form of reinforcement in which a primary reinforcer is presented. Sometimes called an unconditioned reinforcer, this is a stimulus that does not require pairing to function as a reinforcer and most likely has obtained this function through the evolution and its role in species' survival.

Examples of primary reinforcers include sleep, food, air, water, and sex. Other primary reinforcers, such as certain drugs, may mimic the effects of other primary reinforcers. While these primary reinforcers are fairly stable through life and across individuals, the reinforcing value of different primary reinforcers varies due to multiple factors (e.g., genetics, experience). Thus, one person may prefer one type of food while another abhors it. Or one person may eat lots of food while another eats very little. So even though food is a primary reinforcer for both individuals, the value of food as a reinforcer differs between them.

Often primary reinforcers shift their reinforcing value temporarily through satiation and deprivation. Food, for example, may cease to be effective as a reinforcer after a certain amount of it has been consumed (satiation). After a period during which it does not receive any of the primary reinforcer (deprivation), however, the primary reinforcer may once again regain its effectiveness in increasing response strength.