There are many ways in which confidence can be expressed, both in the real world and in the research lab. For example, Yaniv and Foster (1995) present the concept of grain size. People communicate their confidence in an estimate via the precision (grain size) with which they express it." I think it was during the last half of the nineteenth century" implies a different degree of confidence than" I think it was around 1875." Listeners expect speakers to choose a grain size appropriate to their level of knowledge. People also use a variety of verbal probability terms to describe confidence in their predictions, choices, and estimates (eg," I'm pretty sure...,"" It's definitely not...,"" I really don't know, but..."), which people understand to imply different degrees of certainty (Wallsten & Budescu, 1983; Zimmer, 1984).

In the lab, most studies use one of three predominant paradigms. The two most often used involve providing a series of factual questions for which two alternative answers are given, one of which is correct. With the half-range format, questions take the following form:" Who lived longer-Ho Chi Minh or Claude Monet?" Judges select the answer they think is more likely to be correct and express their confidence using a numerical probability scale ranging from. 50 to 1.0. With the full-range format, judges receive the statement" Ho Chi Minh lived longer than Claude Monet did"