Psychology Expert’s Testimony on the Process of Memory Formation Admitted
Posted on June 6, 2025 by Expert Witness Profiler
In October 2019, Nan Morgan McCartney was severely burned while attempting to start a fire in her backyard firepit. She used a plastic gasoline container manufactured by Scepter.
McCartney has given multiple different accounts of the incident over time, but the most recent account (in her deposition) is that she was trying to pour gas from the plastic container on the previously lit but not actively burning kindling in the firepit when gas vapor from the container came in contact with an unseen ember in the firepit and caused a “flashback explosion” of the gas in the container.
Scepter disclosed Dr. Charles Weaver as an expert to testify about the science of forming memories and factors that can affect memory recollection.
The Plaintiff filed a Daubert motion to exclude Weaver’s expert testimony.
Psychology Expert Witness
Charles A. Weaver III is currently Professor & Chair of Psychology and Neuroscience at Baylor University. He has published in the areas of memory and language, the relationship between confidence and memory, flashbulb memory (“where were you on 9/11?”), and eyewitness identification.
Weaver has served as a forensic expert in civil and criminal cases in more than 30 states and has testified in both federal and state courts, for both prosecution and defense.
Discussion by the Court
Relevance
McCartney argued that Weaver’s opinions are not helpful or reliable and that they should be excluded under Fed. R. Evid. 403. According to McCartney, issues of witness memory and veracity are not proper subjects of expert testimony since they are within the exclusive purview of the jury and the common experience of jurors.
Since one witness (expert or not) may not directly testify about the credibility of another witness, the Court held that Weaver cannot testify that McCartney’s current account of the incident was unreliable. Therefore, because Weaver will not be permitted to testify as to the veracity of McCartney’s current description of the incident or comment on the reliability of her memory, there is little danger of the jury being confused about their role in assessing McCartney’s credibility. However, Weaver’s expert testimony about how memories are formed and how they can be influenced over time will be helpful to the jury because those issues are grounded in science and are not entirely within the common experience of jurors.
In other words, Weaver will be permitted in this case to “testify as to the process of [memory] encoding, particularly in a traumatic situation, memory reconstruction, suggestibility, and post-event information,” but he “will not be permitted to opine on the ultimate issue of whether [Plaintiff’s] testimony is credible or incredible.”
Reliability
The Court did not overlook McCartney’s argument that Weaver’s opinions are unreliable because they did not “fit the facts of the case” for a variety of reasons, including the fact that Weaver is a “quintessential expert for hire.” The fact that Weaver did not interview McCartney does not undermine the reliability of his opinions since he is only being allowed to testify about the scientific basis for memory formation and alteration generally, not the veracity of McCartney’s current account of the incident. Finally, the fact that Weaver is a “career witness” and that his testimony has been excluded in other cases might be fodder for cross-examination, but it did not warrant exclusion of his testimony altogether.
Held
The Court granted in part and denied in part the Plaintiff’s motion to exclude Dr. Charles Weaver’s opinion under Daubert.
Key Takeaway:
Weaver’s testimony on the science of forming memories will “provide the jurors with the tools they need to evaluate Plaintiff’s claims of lost and recovered memories” and allow the jury to “decide for itself whether Plaintiff’s ‘newly found’ recollections are reliable and credible, or, alternatively, whether those she shared with emergency medical and police personnel contemporaneous with [the incident] are more credible and reliable.”
Case Details:
| Case Caption: | McCartney V. Myers Industries Inc Et Al |
| Docket Number: | 3:23cv7038 |
| Court Name: | United States District Court, Florida Northern |
| Order Date: | May 29, 2025 |
