I just read
this article and it says some interesting things about the link between what we think we know and how we perceive our environment in different mindsets.
Here are some snippets:
Psychologists Ulrich Weger and Stephen Loughnan recently asked two groups of people to answer questions. People in one group were told that before each question, the answer would be briefly flashed on their screens — too quickly to consciously perceive, but slow enough for their unconscious to take it in. The other group was told that the flashes simply signaled the next question. In fact, for both groups, a random string of letters, not the answers, was flashed. But, remarkably, the people who thought the answers were flashed did better on the test. Expecting to know the answers made people more likely to get the answers right.
In an eye exam, we are used to start experiencing problems at the bottom third of the eye chart, where letters start to get small. In another experiment, Ellen Langer and colleagues showed people a shifted chart. At the top, it included letters equivalent to the medium-size letters on the normal eye chart and the chart progressed to letters of very small size at the bottom. Because people were expecting to read the top two thirds of the shifted chart as well, they were able to read much smaller letters.
For example, when subtle cues in an environment trigger thoughts about a predator, that in turn triggers physiological changes that prepare the body for the impending confrontation even before the predator comes into sight.