Identifying the Halo/Horns Effect with a Performance Review System

Most managers would like to think they’re being as fair as possible when it comes to completing reviews in their performance review system. Many tend to spend hours poring over each comment, every score. But when they step back, are all of their high-performers consistently scoring high in all categories? Are all of the low performers scoring low in every category? These managers might be falling victim to the Halo/Horns Effect.


The Halo/Horns Effect is a type of cognitive bias where a person’s impression of another can substantially influence one’s thoughts and feelings about that person. Psychologist Edward Thorndike first wrote about the Halo Effect in 1920. Thorndike performed a simple study in which he asked two high-ranking officers to evaluate their soldiers on physical qualities such as neatness, and mental qualities like intellect and leadership. The results of the study showed that if a soldier was rated high in one area, he also tended to be rated highly in all other areas.


There’s a flip side of the Halo Effect — the Horns Effect. A common workplace example of the Horns Effect might be one poorly performing employee diminishing the reputation of their entire department.


Both effects are a very real part of the performance appraisal process. Modern studies have shown that managers who rate an employee high in one or two key areas of performance tend to give favorable scores in all aspects of performance. The same goes for those managers that rate employees poorly in certain area; they tend to see a poorer rating overall.


So what are managers to do? How can they avoid falling victim to the Halo/Horns Effect, especially during appraisal time? The first key is documentation; a manager must take notes on all aspects of performances throughout the year. Having a healthy list of positive and not-so-positive aspects of performance gives the manager a more well-rounded view of the employee. Without notes, managers can tend to base their evaluations around one event or a recent memory of events.


Nobody is equally great at every aspect of their job so keep an eye out for reviews that might be consistently skewed high or low with little variation or a repeated use of only a few work examples throughout the review. Be sure managers know about the pitfalls of the Halo/Horns Effect so they can be cognizant of their appraisal and give useful feedback that employees can use in their continued growth in the workplace.