A final set of biases shows how expectations can shape reality itself, for better and worse. The Pygmalion effect (also called the Rosenthal effect) demonstrates that higher expectations tend to produce improved performance: teachers who expect students to succeed elicit better work from them, just as managers who expect excellence tend to receive it. The Golem effect is the dark mirror: low expectations erode performance, as students and employees internalize the doubts of those who evaluate them. Authority bias and automation bias extend this pattern into the realm of expertise and technology. Authority bias leads us to attribute greater accuracy to the opinions of authority figures, even when those figures are not experts in the relevant domain. Automation bias leads us to over-rely on automated systems, sometimes ignoring contradictory information from non-automated sources, even when those systems produce errors.
Other biases in this family concern how we evaluate and remember people. The halo effect, discussed earlier as a perceptual bias, also operates in social evaluation: an overall positive impression in one area, such as attractiveness or likability, influences judgments about unrelated traits. Peak performance bias leads us to evaluate people by their best moments rather than by their typical behavior, which can produce unrealistic expectations in hiring, relationships, and self-evaluation. The Pratfall effect offers a counterintuitive counterweight: a highly competent person often becomes more likeable after committing a minor mistake, because the slip makes them seem more human and approachable.
Two effects from cognitive dissonance theory round out the picture. The Ben Franklin effect shows that doing a favor for someone tends to increase our liking for that person, because we rationalize the effort by upgrading our opinion; Franklin famously asked a rival to lend him a rare book, and the request transformed their relationship. Effort justification works similarly: the more we have struggled to achieve something, the more we value the outcome, which is why harsh initiations can make group membership feel especially rewarding and why completed projects feel more valuable than the labor invested would suggest. Together, these biases show that expectations are not just passive forecasts but active forces that shape what we perceive, how we perform, and how we come to value the things we have built.