Making Good Decisions with Minimal Information: Simultaneous and Sequential Choice

The adaptive pressures facing humans and other animals to make decisions quickly can be met both by increasing internal information-processing speed and by minimizing the amount of information to be used. Here we focus on the latter effect and ask how, and how well, agents can make good decisions with a minimal amount of information, using two specific tasks as examples. When a choice must be made between simultaneously-available options, minimal information in the form of binary recognition (whether or not each item is recognized) can be used in the recognition heuristic to choose effectively. When options are encountered sequentially one at a time, minimal information as to whether or not each option is the best encountered so far is sufficient to guide agents using a simple search-cutoff rule to high performance along several choice criteria. Both of these examples have important economic as well as biological applications, and show the power of simple fast and frugal heuristics to produce good decisions with little information. This revised version was published online in August 2006 with corrections to the Cover Date.     

Royal African Company Share Prices during the South Sea Bubble

Price bubbles provide a unique opportunity to test whether investors act rationally and have sufficient knowledge of the economic environment in which they trade. We focus our attention on the 1720 South Sea bubble episode as experienced by a company not involved in governmental debt financing—the Royal African Company. Following the example of the South Sea Company, the Royal African Company lent its funds to equityholders at a preferential rate. Recognizing this benefit along with the announced dividends explains a large portion of the bubble. Furthermore, the unexplained residual does not behave like an exploding bubble, casting doubt that speculative excess motivated market participants in 1720. Our findings are indeed consistent with investor rationality, and the unexplained residual suggests that we are missing information that was available to the British financial market in 1720.