From the thesis abstract: "This thesis reports the results of a study which tested participants' abilities to recall five different types of computer passwords. Each participant was assigned in a randomized procedure to one of six response intervals. Recall testing of computer-generated passwords, user-created passwords, passphrases, associative passwords and cognitive passwords was conducted using a computer program which simulated system log-on procedures. This study indicates the relative merits of these five password types are more difficult to distinguish when data are collected in the realistic setting of a log-on simulation instead of via paper surveys, as was done in previous research."
Defense Technical Information Center (DTIC): http://www.dtic.mil/dtic/