Prospect Theory
Overview
Prospect Theory is a psychological model that describes how individuals make decisions involving risk and uncertainty. Developed by psychologists Daniel Kahneman and Amos Tally in 1979, the theory revolutionized the field of economics by challenging "Expected Utility Theory," which assumed that humans are perfectly rational actors who always seek to maximize their total wealth. Instead, Prospect Theory suggests that people evaluate potential outcomes based on perceived gains and losses relative to a specific starting point, rather than looking at their final state of wealth. This shift in perspective allows for a more accurate understanding of why human behavior often appears irrational or inconsistent during economic and social decision-making processes.
Key Ideas
The core of Prospect Theory rests on several psychological phenomena that influence how we perceive value. The most prominent is loss aversion, which posits that the psychological pain associated with a loss is significantly more intense than the pleasure derived from an equivalent gain. For example, the distress felt after losing $100 is typically much greater than the satisfaction experienced after winning $100.
Another fundamental concept is reference dependence. Rather than assessing outcomes based on absolute wealth, individuals evaluate them relative to a "reference point," which is often their current status quo. A person might view a $50 bonus as a significant gain if they expected nothing, but may perceive it as a loss if they were expecting a $100 bonus.
Furthermore, the theory describes diminishing sensitivity. As gains or losses increase in magnitude, the marginal impact on an individual's perception decreases. The difference between winning $10 and $20 feels much larger than the difference between winning $1,010 and $1,020. This leads to a characteristic S-shaped value function: people tend to be risk-averse when facing certain gains (preferring a small sure thing over a risky gamble) but become risk-seeking when faced with certain losses (taking a large gamble to avoid an inevitable loss).
Finally, probability weighting explains how humans misinterpret likelihoods. People often overweight very low probabilities, such as the chance of winning a massive lottery jackpot, while underweighting high-probability events that are not certain.
Applications
Prospect Theory has implications for everyday life, particularly in finance and marketing. In personal investing, it explains the "disposition effect," where investors hold onto losing stocks too long in hopes of breaking even (risk-seeking in losses) while selling winning stocks too early to lock in a gain (risk-aversion in gains).
In consumer behavior, marketers utilize loss aversion through tactics like "limited time offers" or "free trials." By framing an offer as something the consumer might lose if they do not act immediately, companies tap into the psychological drive to avoid regret. Additionally, the way prices are framed, such as highlighting what a customer "saves" versus what they "spend, "directly manipulates the user's reference point.
Significance
The significance of Prospect Theory lies in its role as a cornerstone of behavioral economics. It provided the empirical evidence needed to move beyond the "rational man" model of classical economics, acknowledging that human cognitive biases are predictable and systematic.