Halo effect
The halo effect is a bias in which one positive impression of a person, product or brand spills over into judgments of its other, unrelated qualities. A negative first impression works the same way in reverse, sometimes called the horn effect.
How it works
The psychologist Edward Thorndike named it in 1920, after finding that officers who rated soldiers highly on one trait rated them highly on unrelated traits too. One global impression drove every rating.
In research, the halo effect distorts ratings: participants who like a product's look rate its ease of use higher, and a well-known brand scores better on features it shares with rivals. It also affects researchers, who may interpret a charismatic participant's comments more favorably. Countermeasures include rating attributes separately, asking about specific experiences instead of general impressions, testing unbranded versions and comparing ratings against observed behavior, since what people do is less exposed to a halo than what they say.
A worked example
Identical blenders, one with the brand's logo and one without, go to two groups of 200 shoppers each. The branded version scores 8.1 out of 10 for "easy to clean", the unbranded version 6.9. Since nothing else differs, the 1.2-point gap can be attributed to the brand.
Related
Automate this in Pulse
Price, delivery and support rated separately in a Pulse survey give a team the pattern a halo effect leaves, ratings that rise and fall together from one respondent to the next.