Biases in thinking
Halo effect
One good trait colours how people judge everything else, so an attractive or well-known product is assumed to be good in other ways too.
A polished first screen makes people assume the rest is just as well made; a trusted brand gets the benefit of the doubt on a new product. It works in reverse as well.
It's why first impressions and craft matter, and why research participants who like a brand rate its features more kindly. Separate the questions to get honest answers.
In practice
Testers rate a beautifully designed prototype as easier to use, even when it takes them longer to finish the task.
Common mistake
Relying on the halo instead of fixing the product. It buys patience, not loyalty.
Where it comes from
Named by psychologist Edward Thorndike in 1920, after military officers' ratings of their soldiers on unrelated qualities rose and fell together.