3 famous experiments proving that rewards do not nurture but can reduce intrinsic motivation

3 famous experiments proving that rewards do not nurture but can reduce intrinsic motivation. Learn about the Soma effect, large rewards, and the candle problem through psychological studies.

3 Experiments Proving Rewards Can Kill Intrinsic Motivation

Do rewards always help increase performance and boost motivation? The following experiments will make you rethink.

🎲 Experiment 1: The Soma Puzzle and the “Reward Kills Passion Effect”

Edward Deci – a pioneering psychologist in motivation research – conducted a famous experiment with the Soma Puzzle assembly game.

He divided participants into three groups:

Group 1: Told in advance that if they performed well, they would receive a “Skilled Player Certificate.”
Group 2: Not told anything beforehand but received a surprise reward after playing.
Group 3: No reward – simply played.

Results after two weeks: Groups 2 and 3 kept playing passionately as before. But Group 1 – knowing about the reward in advance – played less, with less focus and enthusiasm.

Deci concluded: Conditional rewards (“if you do well then...”) reduce intrinsic motivation. People stop doing things for the joy but for the expected outcome. And when the outcome disappears – the passion fades away too.

“You used to love your work. But when rewards are tied to KPIs – waking up each morning becomes a battle.” – Psychology & Applications Book

💰 Experiment 2: Big Rewards Can Kill Performance

A research team including Dan Ariely and three other economists conducted an experiment in India with 87 people.

They divided them into three groups:

Group 1: Small reward – equivalent to one day’s wage.
Group 2: Medium reward – equivalent to two weeks’ salary.
Group 3: Very large reward – equivalent to five months’ income.

Surprising result: The group receiving the large reward performed the worst. They were stressed, unfocused, and unable to do well on thinking or reflex tests.

In 8 out of 9 tests: The higher the reward → The worse the result.

Explanation: Large rewards become psychological pressure. When people work only for rewards, they tend to “freeze” and lose mental flexibility.

🕯️ Experiment 3: The Candle Problem and the Narrowing of Thought

The classic creativity problem: Participants are given a candle, a box of tacks, and a box of matches, asked to attach the candle to the wall so that wax doesn’t drip onto the table.

Correct solution: Use the box of tacks as a candle holder. But this requires overcoming “functional fixedness.”

The experiment compared two groups:

Group with cash reward
Group without reward

Result: The rewarded group took on average 3 and a half minutes longer to solve.

Reason: When motivated by rewards, thinking tends to “narrow.” Instead of exploring flexibly, they are limited by “doing it right to get the reward.”

“Creativity doesn’t arise from the pressure of rewards, but from a safe space to fail, to try, and to think differently.” – Psychology & Applications Book

📌 Conclusion – When Rewards Become a Double-Edged Sword

The above three experiments show: Rewards are not always effective. Without skillful use, rewards can:

Reduce intrinsic motivation
Create psychological pressure
Narrow creative thinking
Decrease performance

In modern human resource management, what matters most is building an environment that truly nurtures motivation – where employees work because they are trusted, learning, and connected to deeper meaning rather than just “hitting the bonus targets.”

SEO Keywords: intrinsic motivation, Soma effect, counterproductive rewards, Dan Ariely, candle problem, work performance, creativity, applied psychology, human resource management, Drive Daniel Pink