Why and when peer prediction is superior to self-prediction: the weight given to future aspiration versus past achievement

Peer predictions of future behavior and achievement are often more accurate than those furnished by the self. Although both self- and peer predictions correlate equally with future outcomes, peers tend to avoid the degree of overoptimism so often seen in self-predictions. In 3 studies, the authors tested whether this differential accuracy arises because people give more weight to past behavior when predicting others, but emphasize agentic information, in particular data about their aspiration level, when predicting the self. Studies 1 and 3 showed that the exact same participants rated past behavior more diagnostic of future performance when predicting another person but viewed aspiration-level data as more valuable when someone else was trying to predict them. In Studies 2 and 3 (predicting an upcoming exam score and performance in a lab task, respectively), participants gave greater weight in self-predictions to aspiration-level data than did a yoked peer, who instead gave greater weight to evidence of past achievement. This differential weighting explained why peer predictions tended to be less optimistic and, thus, more accurate. Discussion centers on strategies for predicting future behavior and why people may remain ignorant of their own incompetence despite feedback.