Determining the nature of jurors' knowledge about factors influencing eyewitness memory is critical for judges' decisions to admit expert testimony. Past empirical research has primarily assessed such knowledge using responses to survey questions. Yet, research from a variety of fields suggests that expressed beliefs may over- or under-estimate the ability of respondents to act appropriately when faced with a situation where such knowledge is relevant. Participants in this study evaluated the accuracy of eyewitnesses depicted in brief trial transcripts and answered survey questions to assess their beliefs regarding the same eyewitness memory issues. Results revealed that participants' performance on the transcripts did not correlate with their survey responses for most issues. Our findings highlight some potential strengths and weaknesses of survey measures of knowledge about eyewitness memory, and suggest the need for more diverse research investigating people's understanding and use of such knowledge. Copyright © 2009 John Wiley & Sons, Ltd.