As the use of information technology continues to bring a dramatic increase in the amount of data available to managers, researchers have noted that having too much data can be as much of a problem as having too little. It becomes very important to understand the effects of "information explosion" on the way managers perform their work. This study examines the effect of the amount of available data on the process and outcome of thinking within a context where managers are equipped with computing tools. The purpose of this study is to better understand how managers respond cognitively to increased information availability. In this experiment with 104 MBAs three groups of subjects were asked to identify high and low potential market categories for effective direct mail sales based on three different amount of computer-based socioeconomic data designed based on existing research on cognition and information overload. Analyses of the outcomes showed that the group with medium amount of data used data and computer-based analysis tools most effectively and efficiently. We expect that the study will provide us a base to relate future MIS research to theories on cognition in such related fields as psychology and organizational behavior.