Secondary reinforcement and number of primary reinforcements.

E and coworkers worked with pigeons in a small lab chamber.

The birds pecked a key on a variable-interval schedule.

Each food pellet came with a short red light. Later the light alone kept the birds pecking.

The team changed how many pellets each red light had been paired with.

More food pairings made the red light a stronger reinforcer.

Pecking speed went up, but not in a straight line.

Doubling the pairings did not double the response rate.

Todorov et al. (1984) later showed that how often you get food matters more than how big each piece is.

Wilkie et al. (1981) found that smaller food drops shift the response curve right, so you need more frequent delivery to keep rates high.

Together these studies tell the same story: reinforcer power grows with amount and with rate, but in a curved, not linear, way.

When you condition tokens, praise, or stickers, pair them with primary reinforcers many times.

Do not expect behavior to double just because you doubled the pairings.

Watch the response curve level off and adjust schedule density instead of chasing ever bigger jackpots.