Dr. Sterling conducted a laboratory experiment to investigate the effect of post-event discussion on the accuracy of eyewitness testimony. She recruited a sample of 15 academic staff from her university's psychology department and showed them a video of a daylight mugging. Half of the participants then discussed the video in pairs, where one member was a confederate who deliberately introduced misleading information about the perpetrator wearing a bright green backpack. The remaining participants sat in silence. Dr. Sterling then used a free-recall written report to assess their recall of the perpetrator's clothing.