Anchoring and adjustment heuristic that influences the way people intuitively assess probabilities.  Most examples of anchoring and adjustment heuristics are concerned with numerical judgments.  For instance, if asked whether the population of Canada was greater or less than 30 million, you might give one or other answer. If then asked what you thought the actual population was, you would very likely guess somewhere around 30 million, because you have been anchored by the previous answer.