ABSTRACT
We propose a model of the representation and processing of uncertainty and use it to account for data from an experimental study of the use of probability words. Given two sentences, one using a probability word and the other phrased in terms of reasons-to-believe, subjects were asked to judge if the second was an acceptable paraphrase for the first. For certain word/paraphrase pairs there was a high degree of consensus about acceptability, for others the subjects were divided. We model the decision process as involving two stages. First, a concrete “mental” model is constructed which is consistent with the first phrase. The second phrase is then tested for compatibility with this model. In simulations two different representations for the meanings of phrases were tested, one based on probability intervals, and one based on qualitative argument structures. Both versions of the model give a good account for the data, both in terms of which paraphrases are judged to be acceptable and the relative proportions of subjects agreeing or disagreeing.
