The Halo Effect: Why People Often Judge a Book by Its Cover

• We form a first impression of someone, then try to prove that that impression is right.
• We may struggle to separate the different traits that an entity is composed of. For example, if we try to assess someone's competence at work, we take irrelevant facts into account, such as how likeable or confident the person is.
• When we have to assess complex factors, we pick the features that stand out or are easy to understand to reduce our cognitive load.
• We rely on past experience.
• We rely on mental shortcuts.

The halo effect influences how you judge others. Just because someone has a single positive trait doesn't mean you should form a favourable opinion of them. Conversely, just because they have a single negative quality doesn't mean you should form a negative impression.

The most effective way to withstand the halo effect is to slow down your reasoning process.

You can take advantage of how other people view you and the things you make.

For example, we can take into account how our traits and behaviours in one area will influence how other people perceive us in different areas and how they will observe us overall.

• The halo effect in marketing: The halo effect can also influence how we judge things, such as products and companies. For example, if you have a positive impression of a specific brand, you're more likely to buy products from that brand.
• The horns effect: Our negative opinion of someone or something in one domain will influence our impression of them in other domains. For example, if you dislike a product's looks, you may assume the product will have poor performance, even if it's not the case.

Psychologist Edward Thorndike first wrote about the halo effect in his 1920 paper "A Constant Error in Psychological Ratings". He notes that people tend to think of a person in general as relatively good or rather inferior and to judge the qualities of a person by this general feeling.

Thorndike does not use the term 'halo effect' in the paper but does use the word 'halo' when referring to this phenomenon.