What is the Sunk Cost Fallacy?
The sunk cost fallacy is a cognitive bias. It compels individuals to continue investing time, money, or resources into a project or decision based on previously invested resources. They do this rather than considering future benefits. This psychological phenomenon often leads to poor decision-making. People feel reluctant to “waste” what they’ve already invested.
The Psychology Behind the Sunk Cost Fallacy
Our innate aversion to loss leads to the sunk cost fallacy. It also arises from the cognitive dissonance associated with abandoning a prior investment. Key psychological drivers include:
- Loss Aversion: Humans feel the pain of loss more acutely than the pleasure of gain. Abandoning a previous investment is perceived as a loss, even when it might be the rational choice.
- Cognitive Dissonance: People want their actions and beliefs to align. Admitting a previous investment was a mistake can create psychological discomfort.
- Commitment and Consistency Bias: Once we commit to a decision, we are motivated to act consistently with it, even when new information suggests otherwise.
- Overconfidence Bias: People often overestimate their ability to turn around a failing situation.
Relationships with Other Cognitive Biases
- Status Quo Bias: The tendency to prefer things as they are makes people reluctant to make changes.
- Anchoring Bias: The initial investment acts as an anchor, distorting our judgment about current or future value.
- Endowment Effect: We assign higher value to things we own, increasing attachment and unwillingness to let go.
Studies on the Sunk Cost Fallacy
- Arkes & Blumer (1985): Demonstrated the sunk cost effect in real-life scenarios. Participants who were made aware of their past investments were more likely to persist with an unprofitable decision.
- Thaler (1980): Explored how sunk costs influence consumer behaviour, showing that people irrationally persist with purchases to “justify” prior expenses.
- Whyte (1986): Found that managers often continue funding failing projects to avoid admitting to a bad initial decision.
See This Bias In Action
The more we’ve invested, the harder it is to walk away — even when we should:
- What Netflix Knows About Gym Member Retention — sunk cost as one of the three retention levers (alongside switching costs and relationship quality).
By recognising the sunk cost fallacy and its psychological underpinnings, individuals and organisations can make more rational decisions. They can adopt forward-thinking approaches that break free from the cycle of throwing good money after bad.