Abstract In computer-supported information exchange, people frequently tend to withhold their own information and free-ride on the others' contributions. In doing so, they save costs (time and effort) and maximize their own benefit. However, if everyone behaved in this way, there would be no information sharing at all. In this experiment, we tested if the presentation of a random number could serve as a cognitive anchor and influence the amount of shared information. The experimental setting had all the features of an information-exchange dilemma. Before participants could share information, a random generator presented a random number. It was found that this number served as a cognitive anchor and influenced both the participants' behavioral intentions and their actual behavior. Particularly, the high anchor increased cooperation, even though enhanced cooperation was obviously detrimental to the individual's own benefit.