Mitchell Eisen Forensic Psychology Eyewitness Memory Lab

Mitchell Eisen

Professor and Director, Forensic MS option

College of Natural and Social Sciences
Department of Psychology
Office: King Hall C3060
Research Lab: King Hall D3071B
Telephone: 323-343-5006



Dr. Eisen is Director of the Forensic Psychology Graduate Program here at Cal State L.A. Dr. Eisen is also the Research liaison for the Partnership between CSULA and the Juvenile Court, and a member of the Coordinating Council for the California Forensic Science Institute (CFSI). In addition, Dr.  Eisen serves on the panel of experts for the Los Angeles County Superior Court in the area of eyewitness memory.


Teaching interests include psychology and the law, human memory, assesment, and psychopathology.


New research from our lab on SHOWUPS done by police in real world conditions: How suggestive are they? The US Supreme Court has acknowledged that showups are inherently suggestive, however, they are still used quite often in day to day police practice. These are the first studies done to examine showups in the field under real world conditions where the witnesses believed their identification would result in the arrest of the suspect. Across these two experiments over 600 students witnessed a theft and participated in a live showup that was conducted by local law enforcement. The crime and investigation were staged repeatedly for small groups of six participants under ideal witnessing conditions: Long clear exposure to the thief and 20-minute delay before the showup.  A uniformed officer responded to the reported crime and then escorted witnesses to meet with two other officers who conducted a live show-up with an innocent suspect. 



What happens when a witness either does not choose or selects a filler from the lineup and the officer prompts them to continue their search?

“Does Anyone Else Look Familiar?”: The Effects of Subtle Disconfirming Feedback on Confidence Judgments and Lineup Decisions

This study was designed to examine the effect of subtle disconfirming feedback on witness confidence judgments and lineup decision-making. Subtle disconfirming feedback took two forms in this study. Participants’ lineup decisions were either questioned by asking them in a neutral tone if they were sure about their choice and if anyone else looked familiar, or this same questioning was done in concert with skeptical gestures (e.g., shaking one’s head from side-to-side and squinting). It was hypothesized that subtle disconfirming feedback would lead to a decrease in witness confidence and the selection of additional photos, and that the effect would be strongest when the skeptical gestures were employed. In addition, we examined the relationship between confidence change following post-identification feedback and both memory for the perpetrator and suggestibility as measured by errors on misleading questions related to the event. Results revealed that subtle disconfirming feedback led to a significant decrease in confidence. Also, when participants were asked if anyone else looked familiar, more than 40% selected an additional picture; and of that group, the second choice was made with equal or greater confidence than their original decision 30% of the time. Moreover, suggestibility as measured by errors on misleading question was related to confidence change.



What happens when one witness hears another say that the perpetrator had a distinctive tattoo, and only one guy in the lineup has that type of tattoo; but he is not the actual culprit?

The effects of plausibility and retention interval on eyewitness conformity

One hundred and seventy seven participants watched a video of a simulated carjacking. Right after the video witness statements were taken from each participant; as they were asked to describe what they just witnessed.  All sessions involved five participants, consisting of two confederates and three subjects. The confederates’ each made three errors in their reports (6 in total). These errors included included three pieces of plausible and three pieces of implausible information about the culprit. These suggestions involved distinctive and forensically relevant features of the perpetrator; including the suggestion that the perpetrator had a tattoo on his neck. After a 5-minute, 50-minute, or 48-hour delay, free recall was obtained from each participant individually, and they were asked to pick the perpetrator from a target present or absent photo array.  In each of these photo arrays a filler with a tattoo on his neck was included. Results revealed a main effect for plausibility, the plausible misinformation was more likely to be included in the participants memory reports at each retention interval. Also, participants also selected the filler with the tattoo on his neck 38% of the time at the 5 and 50-minute retention intervals, and 36% of the time at 48 hours.



In this series of studies we examined how the introduction of bias by depicting the defendant as a gang member can affect jurors memory for the evidence and their decision-making. In four different studies over 1000 participants viewed three different abbreviated simulated trials where biased was systematically varied, as the defendant was either described as being gang affiliated or not. Consistently jurors voted guilty more often when the gang bias was induced.  Also, after deliberating in groups, many jurors continued to voted guilty in gang bias conditions even when reasonable doubt was clearly established, as evidence by no guilty verdicts in the no bias condition.


Ripple Effects: How Biased Evidence Can Cause Distortion in Jurors’ Memory

Pizzaro et al, (2006) proposed the theory of Ripple effects to explain how judgments of moral responsibility can have biasing effects on people’s memory for details of a crime. This research highlights the importance of understanding how potentially prejudicial information about a defendant can affect jurors’ perception of, and memory for, the evidence presented.  This is issue come up often in gang cases. In most US states, if the accused party is on record as having any association with gangs, it is common for that crime to be charged as  ‘gang-related’. Eisen et al, (2013) noted that labeling a defendant as a ‘gang-member” can induce a confirmation bias, leading jurors to filter the evidence through a negative stereotype, resulting in greater attention to information that confirms the established bias. However, there is also good reason to believe that this type of negative stereotype can have a ripple effect that extends well beyond how jurors filter the information, and also affects their memory for the evidence. This study was designed to examine how Ripple effects can bias jurors’ retrospective memory for the evidence presented in a trail where the defendant is charged with a gang-related offense.

Two experiments were conducted. In each experiment, participants viewed a simulated trial designed to establish reasonable doubt where the presence of gang evidence was manipulated. In both trials, the only evidence presented was a tentative eyewitness identification.  It was hypothesized that when the defendant was identified as a gang member, jurors would be more likely to vote guilty, even when reasonable doubt was established. In experiment 1, participants (n=212) viewed a trial involving robbery; in experiment 2, participants (n=235) viewed a more serious crime involving a murder. In the filmed trials, the defense attorney and prosecutor were played by judges, the victim/eyewitness was played by an actor, the investigating officer was played by a local police official, and the people’s gang expert was played by an officer who frequently provides gang testimony in court. Participants provided verdicts before and after deliberations.

Results demonstrated that when there was no mention of gang evidence, only one person out of 249 participants voted guilty across trials after deliberations. The fact that only one juror in the no-gang condition voted guilty shows that reasonable doubt was clearly established.  However, a significant minority of jurors continued to vote guilty when the defendant was described as a dangerous gang member (10% for robbery vs. 19% for murder). Qualitative analyses of the mock jurors post deliberation responses show evidence of a ripple effect. When asked why the participants voted guilty, in each experiment, the majority of participants in the gang condition noted that the defendant’s prior criminal history played a role in their decision. However, no evidence of this was offered in the trial.  It appears that hearing expert testimony on the operation of the gang lead jurors to incorrectly recall that evidence of prior criminal conduct was actually presented at trial.