People are inclined to make decisions based on how readily available information is to them. If you can easily recall something, you are likely to rely more on this information than other facts or observations. This means judgements tend to be heavily weighted on the most recent piece of information received or the simplest thing to recall.
In practice, research has shown (pdf) that shoppers who can recall a few low-price products—perhaps because of a prominent ads or promotions—tend to think that a store offers low prices across the board, regardless of other evidence. And in a particularly devious experiment, a psychology professor (naturally) got his students to evaluate his teaching (pdf), with one group asked to list two things he could improve and another asked to list 10. Since it’s harder to think of 10 bad things than just two, the students asked to make a longer list gave the professor better ratings—seemingly concluding that if they couldn’t come up with enough critical things to fill out the form, then the course must be good.
Eshe Nelson writing in Quartz