Halo effect

The halo effect is a cognitive bias in which an observer's overall impression of a person, company, brand, or product influences the observer's feelings and thoughts about that entity's character or properties. It was named by psychologist Edward Thorndike in reference to a person being perceived as having a halo. Subsequent researchers have studied it in relation to attractiveness and its bearing on the judicial and educational systems. The halo effect is a specific type of confirmation bias, wherein positive feelings in one area cause ambiguous or neutral traits to be viewed positively. Edward Thorndike originally coined the term referring only to people; however, its use has been greatly expanded especially in the area of brand marketing.

The term "halo" is used in analogy with the religious concept: a glowing circle crowning the heads of saints in countless medieval and Renaissance paintings, bathing the saint's face in heavenly light. The observer may be subject to overestimating the worth of the observed by the presence of a quality that adds light on the whole like a halo. In other words, observers tend to bend their judgement according to one patent characteristic of the person (the "halo"), generalizing towards a judgement of that person's character (e.g., in the literal hagiologic case, "entirely good and worthy").

The halo effect works in both positive and negative directions (the horns effect): If the observer likes one aspect of something, they will have a positive predisposition toward everything about it. If the observer dislikes one aspect of something, they will have a negative predisposition toward everything about it.

Edward Thorndike, known for his contributions to educational psychology, coined the phrase "halo effect" and was the first to support it with empirical research. He gave the phenomenon its name in his 1920 article “A Constant Error in Psychological Ratings”. He had noted in a previous study made in 1915 that estimates of traits in the same person were very highly and evenly correlated. In “Constant Error”, Thorndike set out to replicate the study in hopes of pinning down the bias that he thought was present in these ratings.

In "A Constant Error in Psychological Ratings", Thorndike asked two commanding officers to evaluate their soldiers in terms of physical qualities (neatness, voice, physique, bearing, and energy), intellect, leadership skills, and personal qualities (including dependability, loyalty, responsibility, selflessness, and cooperation). His goal was to see how the ratings of one characteristic affected other characteristics.

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