Developmental Job Talk
Dr. Kathleen Corriveau will give a talk entitled "Children's selective trust in informants". Dr. Corriveau is a candidate for the position in the developmental area.
Rain likely. Do you carry an umbrella?
Everyone uses words and phrases such as "likely", "very likely", "doubtful", and "highly unlikely" when there is a degree of uncertainty involved in what they are saying. What do we mean when we use these terms? How likely is "likely" and how much more likely is "very likely"? Perhaps of more importance, do people generally mean the same thing when they use these terms? If someone tells you they think it is unlikely that Lance Armstrong will win another Tour de France, is the probability of his winning that they're trying to communicate the same probability that you're hearing? Whether or not we understand these terms in the same way may not matter very much when we're talking about the Tour de France, but it can have very important consequences if experts are talking about how likely it is that another country is developing weapons of mass destruction.
Cognitive psychologists who are interested in decision making, reasoning or language have examined how we understand terms that express uncertainty both when we use them and when we hear them. Some of their findings are quite surprising. Different people tend to use different words to communicate that something is uncertain. Two people may have identical views about how likely something is to happen but they may use different phrases to express the belief they share. Moreover, when people do use the same terms, they often mean very different things by them. Two people may agree that it's “unlikely” that Lance Armstrong will win another Tour de France but one may think his chance of winning is about 30% while the other may think it's only about 20%.
The issue becomes even more complicated when one takes into account that people will often use the same term to express different degrees of uncertainty in different circumstances depending on factors such as what they think the person they're talking to understands about the topic. When talking to another rider who understands the level of physical conditioning and training it takes to win the Tour de France, a cyclist might restrict the term "unlikely" to a much lower range of probabilities than when talking to a person who doesn't know very much about cycling. In the same manner, a doctor may express her estimate of the probability that a patient will recover using different terms when talking to the patient than when speaking with another doctor even though she is trying to express the same idea in both cases.
Dr. Thomas Wallsten uses experimental methods and mathematical models to study the language of uncertainty. Some of his recent work has explored the idea that people treat a word such as "doubtful" as applying to a range of probabilities. For example, one person might use the term "doubtful" when he thinks the chance that something will happen lies somewhere between 15% and 30%. Moreover, even within this range, he might use the term more often to describe probabilities in the middle than at the extremes. So, he might use “doubtful” most often for probabilities in the 20%-25% range, intermixing it with “highly doubtful” for a range below that and with “unlikely” for a range above it.
This approach, allows Dr. Wallsten to develop a more accurate understanding of what different people mean when they use a common term such as "doubtful" to express a degree of uncertainty. Understanding what different people mean when they use these terms can then be used to improve communication between experts who are called upon to estimate the likelihood that an event will occur and people who have to make a decision based on what the expert tells them. A better understanding of these issues can help government policy makers make better decisions based on what the intelligence analysts tell them and can help patients make better decisions about their medical care after they've heard from their doctor.