["\n\nPurpose\nForensic interviewers often face witnesses who are unwilling to cooperate with the investigation. In this experimental study, we examined the extent to which cooperativeness instructions affect information disclosure in a witness investigative interview.\n\n\nMethods\nOne hundred and thirty‐six participants watched a recorded mock‐crime and were interviewed twice as mock‐witnesses. They were randomly assigned to one of four conditions instructing different levels of cooperativeness: Control (no instructions), Cooperation, No Cooperation, and No Cooperation plus Cooperation. The cooperativeness instructions aimed to influence how participants’ perceived the costs and benefits of cooperation. We predicted that Cooperation and No Cooperation instructions would increase and decrease information disclosure and accuracy, respectively.\n\n\nResults\nWe found decreased information disclosure and, to a lesser extent, accuracy in the No Cooperation and No Cooperation plus Cooperation conditions. In a second interview, the shift of instructions from No Cooperation to Cooperation led to a limited increase of information disclosure at no cost of accuracy. Cooperativeness instructions partially influenced the communication strategies participants used to disclose or withhold information.\n\n\nConclusions\nOur results demonstrate the detrimental effects of uncooperativeness on information disclosure and, to a lesser extent, the accuracy of witness statements. We discuss the implications of a lack of witness cooperation and the importance of gaining witness cooperation to facilitate information disclosure in investigative interviews.\n\n", "Legal and Criminological Psychology, Volume 25, Issue 2, Page 133-149, September 2020. "]