Motivation psychology; social psychology; behavioral science

Deci Effect

Pay and reward people in ways that support the work instead of replacing the work's own meaning. When rewards feel controlling, interest can drop after the reward disappears.

Popularity

Usefulness

Aliases

Reward-Undermining Effect / Undermining Effect of Extrinsic Rewards / Overjustification Effect / Extrinsic Rewards and Intrinsic Motivation

Domains

Education, management, parenting, coaching, product design, gamification, creative work

Definition

The Deci Effect describes a pattern in which outside rewards can weaken a person's built-in interest in something they already enjoy doing, especially when the reward feels like control rather than support.
In research writing, this idea is often discussed alongside the overjustification effect, cognitive evaluation theory, and self-determination theory.

Core Idea

Rewards are not always motivational in the long run. When a reward makes a person feel that they are doing an activity “for the reward” rather than because they choose or enjoy it, intrinsic motivation can decline. Rewards or feedback that support competence and autonomy may avoid this problem or sometimes increase motivation.

How It Works

A person initially finds an activity interesting or satisfying.
An external reward is introduced, especially one that is expected, tangible, or tied to doing the task.
The person may reinterpret their reason for acting: from “I enjoy this” to “I am doing this to get the reward.”
This can reduce perceived autonomy and shift motivation toward external control.
When the reward is removed, voluntary engagement may drop below the original level.
The effect is weaker or may not apply when rewards are unexpected, informational, autonomy-supporting, or used for tasks with little initial intrinsic interest.

Usage Example

A child enjoys drawing. Parents begin paying the child for every drawing. At first, the child draws more, but later may draw less when no payment is offered. A better approach is to praise effort and improvement, provide choice, and avoid making the activity feel like paid labor.

Famous Example

Example: In Edward Deci's early Soma-cube studies, participants worked on puzzles over several sessions. Some were paid during part of the task, and researchers later observed whether they kept playing once the payment stopped.
Why it fits this rule: The setup tested whether a reward changed voluntary interest after the reward was removed.

Use Cases / Situations Where It Applies

Designing classroom reward systems without damaging curiosity.
Managing creative or knowledge workers without turning every task into a transaction.
Building gamified apps where badges, points, or streaks might crowd out genuine interest.
Parenting and coaching, especially when a child already enjoys the activity.
Encouraging long-term learning, reading, coding, music, art, or problem-solving.

When Not to Use or Common Misuse

Do not interpret it as “all rewards are bad.”
Do not use it as an excuse to underpay people; fair compensation is separate from preserving intrinsic motivation.
Do not apply it strongly to boring or low-interest tasks where external incentives may be useful.
Do not reduce the effect to “large rewards are bad.” The key issue is often whether the reward feels controlling, expected, and task-contingent.
Do not assume praise is always good; praise can also feel controlling if it pressures performance rather than supporting competence.

Rule Invention / Origin

Invented by: Not formally invented as a universal “law.” It is associated with Edward L. Deci’s research on external rewards and intrinsic motivation.
Year of invention: No single formal invention year. The key origin is Deci’s 1971 paper, “Effects of Externally Mediated Rewards on Intrinsic Motivation.”
Country / context of origin: United States; experimental motivation research conducted at Carnegie-Mellon University, with Deci affiliated with the University of Rochester.

Short Practical Takeaway

Use rewards carefully: pay fairly, but do not turn an already meaningful or enjoyable activity into something people do only for a prize.