The effects of primary reward on the I.Q. performance of grade-school children as a function of initial I.Q. level.

Researchers gave first- and second-graders a picture-vocabulary IQ test.

Each time a child answered correctly, the adult handed the child a piece of candy right away.

Kids were split by their starting IQ scores: low, middle, or high.

Only the low-scoring children earned higher IQ scores when candy was given.

Middle and high scorers stayed at the same level with or without candy.

A tiny sweet, delivered immediately, lifted the scores that needed lifting.

Alba et al. (1972) warned that rewarding behavior alone does not raise schoolwork accuracy.

The new study agrees: you must reward the actual correct answer, not just sitting still.

McGrother et al. (1996) later showed that group contingencies can beat individual ones for overall class scores.

Together the papers say: tie the reward to the skill you want, then decide if one kid or the whole group should earn it.

If a child scores low on early tests, a quick edible after each right response can unlock better performance.

Use this during assessments, drills, or flash-card reviews.

Keep the reward small and immediate; save group contingencies for class-wide goals later.