In the psychology of affective forecasting, the impact bias, a form of which is the durability bias, is the tendency for people to overestimate the length or the intensity of future emotional states. Overview People display an impact bias when they overestimate the intensity and durability of affect when making predictions about their emotional responses. It is a cognitive bias that has been found in populations ranging from college students (e.g. Dunn, Wilson, & Gilbert, 2003; Buehler & McFarland, 2001), to sports fans (Wilson et al, 2000), to registered voters (Gilbert et al, 1998). Affective Forecasting Research shows that people often make errors about how much positive or negative effect an event will have on us. People mispredict their emotional reactions (how much pleasure or displeasure an event will bring them) when they mispredict how the event will occur. These mistaken projections can lead to mistaken assumptions about the impact of an event on their happiness. Generally, people accurately predict the valence, if an event will generate a positive or negative reaction, but people are less accurate in their predictions about the intensity and the duration of these effects. Mistaken projections To make decisions, people try to predict how an event will play out and what it will make them feel. However, when making these predictions, people are subject to many cognitive biases, including the impact bias. Research shows that people’s projections are often mistaken (e.g. Wilson & Gilbert, 2005; Buehler & McFarland, 2001; Loewenstein & Schake, 1999). Early studies revealed that this phenomenon is a result of people’s inability to anticipate how their feelings will be affected by external factors, and change over time (e.g. Kahneman, 1994). People are more prone to make errors about intensity and duration of affect, than about valence. These mistaken projections affect people’s ability to make decisions that maximize their happiness. Example In Gilbert et al., 1998, there was a conducted study on individuals participating in a job interview. The participants were separated into two groups; the unfair decision condition (where the decision of being hired was left up to a single MBA student with sole authority listening to the interview) and the fair decision condition (where the decision was made by a team of MBA students who had to independently and unanimously decide the fate of the interviewee). Then, certain participants were chosen to forecast how they would feel if they were chosen