December 15, 2016

Fight False Memory (in Your Witness Prep)

By Dr. Ken Broda-Bahm:


Remember when you took that hot air balloon ride as a kid? Or when you played that prank on a teacher by leaving slime on her desk? Or when you caused havoc by spilling a punch bowl at that wedding? Do you remember any of these events? Participants in studies have been induced to recall all of them, falsely. These studies are called “memory implantation studies,” and they demonstrate not just the power of suggestion, or perhaps the pervasiveness of human gullibility, but they also show us a bit of how memory works. According to a recent mega-analysis of these studies (Scoboria et al., 2016), they work, not because participants have poor memories, but because memory itself draws from multiple sources, some of which can be tricked. “The experience of remembering a past event,” they write, “is the result of multiple cognitive systems and processes. Inputs from numerous sources (e.g., records of prior perceptual processing, or prior thoughts, feelings, general knowledge, beliefs, goals, feelings of familiarity, etc.) give rise to an experience of remembering the past.” 

And the induced experience of remembering the past falsely is not a rare or outlier event. The researchers report, “suggestive practices appear to instill a degree of belief in false events in about two-thirds of study participants.” Actually more than two-thirds of study participants (69.7 percent) reached the point of “acceptance” of false memories — an, “I’m sure that happened, but I don’t necessarily remember it” feeling — while nearly half reached the “I remember it happening” point of reporting false memories about the event. Such high levels can be achieved because memory is, as I’ve written before, reconstruction. As the authors write, “One implication of having a reconstructive and flexible memory system is that people can develop rich and coherent autobiographical memories of entire events that never happened.” Of course memory matters when we are litigating about past events. There is what I call a “strong version” of concern over this that applies in criminal law: false confessions, distorted witness identifications, or remembered abuse and victimization that didn’t happen. But I want to write in this post about a “softer version” that may be more common but less noticeable: The power of suggestion that can be an artifact of witness preparation sessions.

The Research: How to Plant a False Memory

Here is the way memory implantation studies usually work. Participants volunteer for what they think is just a general study of memory. They are presented with a description of a number of childhood events. Some of them are true (provided by trusted family members), while others are false. The volunteers, however, think that they all come from the trusted family members. Over the course of two or three sessions, usually spread out over a week or more, the participants are encouraged to recall these childhood events in greater detail.

The researchers use various techniques, like including idiosyncratic personal details in the stories, encouraging visualization of the events, or presenting a suggested narrative of how it happened. The researchers explain that, “Together, these processes may encourage participants to develop perceptually rich and vivid mental experiences that they ultimately misinterpret as memories of the suggested event.”

Transcripts are kept of these sessions, and independent raters, who don’t know which events are true and which are false, review transcripts of these sessions to assess the extent to which the study participants accept and have memories of the events.

In the recent study, the research team obtained the session transcripts from eight peer-reviewed and published studies involving a total of 400 participants, and then developed a consistent and validated system for reviewing those transcripts.

The conclusion: “Given all three of these conditions,” self-relevant information, imagination procedure, and suggested narrative, “we found a false memory rate of 46.1 percent, and an acceptance rate of 69.7 percent.” Apparently, if we are told about a fictitious event and spend time imagining the event occurring, more than two-thirds of us will accept the event as true. 

The Precaution: Minimize the Risk of False Memories in Witness Prep

During a witness preparation session, the witness does not simply answer the question. Instead, there are attorneys and sometimes colleagues present, and the power of suggestion can sometimes come into play: Didn’t you see that memo? I thought you did? I think other team members testified that you did. And this document seems to say you did? Do you think you might have? Before you know it, a very honest witness might be pretty sure that she saw the memo.

There is not just an ethical reason for avoiding that suggestion (though that would be enough), there is a practical reason as well: A witness who strays beyond what they actually remember can get into trouble, and potentially get caught in an inconsistency. So there are a few steps to take to avoid that and keep the memories accurate.

Record Memories Early

In medical malpractice settings, it is often a good idea for the doctors involved to record everything they individually remember, down to the details, and address it all in a protected “To my attorney” letter. That lets counsel know what they’re dealing with and keeps the information preserved and vivid. Down the road, it also can improve testimony by avoiding a bunch of “I don’t remember” responses during deposition or trial.

Avoid Suggestion During Preparation Sessions

Attorneys have different tolerances for this. The vast majority want honest testimony, because that is easier to handle — warts and all — in trial. A few, however, are more likely to favor control, and would testify themselves if they could. The best practice is to listen to the witness, carefully, and avoid either the subtle and overt suggestion that a witness remember anything different than what they recall after their own independent best efforts.

Build a Strong and Confident Witness

As I have written before, witness confidence is one of your most precious assets. So you want to make sure your preparation session is building and not reducing confidence. That is probably the best reason to avoid pushing a witness’s recollection: A strong attorney can probably get a witness to deliver the preferred line, but it probably won’t be confident, or consistent, or able to hold up well in cross by an equally strong attorney from the other side.

One acknowledged limit of memory implantation studies is that it can be difficult to tell the difference between actual false memories and memories that have some element of truth. “Based on this study and on similar work,” the researchers write, “it can be difficult to objectively determine when someone is recollecting the past, versus reporting other forms of knowledge or belief or describing mental representations that have originated in other sources of experience….” And if it is difficult in the laboratory, they continue, “How, then, can we expect therapists, forensic investigators, medical personnel, human resource staff, or jurists to be any better at this task?” The answer is that we can’t expect. But the process requires best efforts, and part of that is remembering that memory is fragile and susceptible to influence.


Other Posts on Memory:


Scoboria, A., Wade, K. A., Lindsay, D. S., Azad, T., Strange, D., Ost, J., & Hyman, I. E. (2016). A mega-analysis of memory reports from eight peer-reviewed false memory implantation studies. Memory, 1-18.

Image credit:, used under license


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