Journal of Economic Behavior and Organization 8 (1987) 137-144. North-Holland STILL SEARCHING John D. HEY University of York, ti¢~li,~ton, York YO ! 5DD, UK Received August 1985, final version received February !986 This paper investigates whether search behaviour is (1) sensitive to the existence of a monetary reward, (2) sensitive to the availability of recall and (3) sensitive to the availability of information. Our results suggested that optimal behaviour increases with information, decreases with recall but (at least for modest amounts of money) is insensitive to the payment structure. In 1982 I published in this journal a report on some preliminary laboratory-type investigations into search behaviour. My main interest then was in behaviour in situations ,,vhere the searchers' initial information was negligible. I discovered that the "actual' rules of search employed by the subjects in my experiments were more akin to 'rules of thumb' than to the "optimal' rule, though the implications of these rules (in terms of the objective function) were remarkably close to the implications of the optimal rale. Other economists [most no:ably Schotter and Braunstein (1981)], investi- gating behaviour in situations where searchers had considerably more initial information, discovered behavieur considerably closer to optimal behaviour. This lends provisional support to the intuitively appealing hypothesis that behaviour approaches the optimal as the information availabI~ to the searcher increases. Conversely, behaviour becomes increasingly subject to apparently arbitrary "rules of thumb' as information decreases. [A related argument can be found in Heiner (1983) who argues that rigidity, and hence predictability, of behaviour increases as the complexity of the environment increases, and as the decision-making ability of the individual decreases]. An alternative interpretation of the 'rules of thumb' findings revolves around the incentives present in my earlier experimental investigations. In those experiments, the subjects were not paid for taking part in the experiment. They were, however, required to 'think aloud' as they carried out the experiments, and their spoken thoughts were tape-recorded for later analysis. Clearly this provides some form of incentive, though naturally there is doubt whether it is of the appropriate form. A monetary incentive would, no doubt, be more appropriate and more natural. 0167-2681/87/$3.50 © i98~, Elsevier Scica~ IJublishers B.V. (North-Holland)