The notion that the co-occurrence of two events is more likely than the occurrence of either event alone. When people are asked to predict the outcomes of events, the added detail, especially when representative of the situation, leads them to increase their estimate of the likelihood of their joint occurrence. For example, in one study, people thought that President Reagan was more likely to provide more federal support for unwed mothers <I>and</I> cut federal support to local governments than he was to simply provide more federal support for unwed mothers (Tversky and Kahneman 1983). See <a href="search.pl?p=representativeness">representativeness</a>.<o:p></o:p></P>
 <ul>
   <li>Tversky, A. &amp; D. Kahneman (1983), “Extensional vs. 
intuitive reasoning: the conjunctive fallacy in probability judgment,” 
<I>Psychological Review</I>, 90, 293-315.</li>
 </ul>