Snap Shot
- The question: How does schizophrenia affect memory and source monitoring, and what does that mean when a complainant, a witness, or an accused person has the diagnosis?
- What the research shows: As groups, people with schizophrenia remember less than comparison groups, largely because of weaker encoding, and make more errors about where a memory came from, especially for things they imagined or generated themselves. Studies from one research group found more confidence in mistaken source judgments, and a scoping review links delusional thinking to source-memory biases and impaired metamemory. Laboratory false-memory rates are often similar to those of comparison groups, and one preliminary study, whose sample size was not available in the summary reviewed, found no greater susceptibility to co-witness misinformation.
- What it does not show: A diagnosis of schizophrenia does not make a report unreliable, and the research cannot say whether a particular person’s account is accurate. Most studies use word lists and small clinical samples, not memory for real events, and functioning varies widely across people and across periods of illness.
- The law: Every person is presumed competent to testify (Rule 601), and memory testimony is governed by Rule 702 and Houser, stays general, and may not vouch for or against a particular witness (Lindsey, Nordstrom). Competence to stand trial and mental responsibility are separate questions; in Arizona, Mott confines mental-disorder evidence on mens rea to the insanity defense.
- Issues for each side: Prosecutors can present research showing that witnesses with schizophrenia are often accurate, while documenting the account early and seeking corroboration; defense counsel can raise source-monitoring and confidence findings tied to specific content and clinical state, without arguing from the diagnosis alone.
Schizophrenia is a serious psychiatric disorder marked by psychotic symptoms, such as hallucinations and delusions, often with changes in motivation, emotional expression, and cognition, including memory. People with schizophrenia come into contact with the justice system in every role. They are complainants and witnesses, and adults with severe mental illness are victims of violent crime at markedly higher rates than the general population: in a random sample of 936 adults receiving outpatient, day, or residential mental health treatment in Chicago, more than one quarter had been victims of violent crime in the prior year, a rate more than 11 times that of the general population after adjustment for demographic differences (Teplin et al., 2005). That sample included people with several serious mental illnesses, not schizophrenia alone. People with schizophrenia are also accused persons, whose memory of events, statements to investigators, and capacity to assist counsel may be at issue.
Courts and parties sometimes treat the diagnosis as if it answered the question of reliability, in either direction. It does not. The research identifies specific memory processes that differ on average between people with schizophrenia and comparison groups, along with considerable overlap between the groups and variation over the course of the illness. The useful forensic questions concern those processes, the person’s condition when the events occurred and when the account was given, and how the account was obtained.
This paper summarizes research on encoding, source monitoring, confidence in memory errors, and false memory and suggestibility, then addresses witnesses and accused persons with schizophrenia, the limits of the evidence, and the governing federal, military, and Arizona law. Related material appears in Memory in Special Populations and Source Monitoring.
Episodic Memory and Encoding
A meta-analysis of 70 studies found a significant and stable memory impairment in schizophrenia, with a large composite effect for recall and a smaller but still significant effect for recognition (Aleman et al., 1999). The size of the impairment was not related to age, medication, duration of illness, or the severity of symptoms overall, although negative symptoms, such as reduced motivation and emotional expression, showed a small association. The meta-analysis is more than 25 years old; its central point is that the differences are not simply a product of acute psychosis.
The research points to encoding as an important source of the difference. In a study of 38 people with schizophrenia and 38 comparison participants, the group with schizophrenia made less use of deep, meaning-based organization when learning word lists, while early storage and retrieval appeared intact (Brébion et al., 1997). Consistent with that, the gap is smaller for recognition, which supplies retrieval support, than for free recall (Aleman et al., 1999). For legal purposes, a person with schizophrenia may give a less complete free narrative than other witnesses; incompleteness is not the same as inaccuracy.
Source Monitoring and Reality Monitoring
Source monitoring is the set of judgments by which people attribute a memory to its origin: whether something was seen or heard, who said it, and whether it was perceived or only imagined, thought, or suggested. Reality monitoring is the subset that distinguishes events that occurred from those that were internally generated (Johnson et al., 1993). Everyone makes these errors at times.
Source-monitoring differences in schizophrenia have been studied extensively because they offer a possible account of hallucinations, in which a person’s own inner speech or imagery may be experienced as coming from outside. A 2022 meta-analysis of 44 studies (1,566 participants with psychosis and 1,175 comparison participants) found poorer source-monitoring performance in psychosis overall, a moderate effect, with the clearest differences for distinguishing internal sources and for items the person had imagined (Damiani et al., 2022). Participants who experienced hallucinations differed from those who did not mainly in errors that attributed internally generated items to an external source. Not every analysis supports a specific deficit. An earlier meta-analysis of associative memory found large differences in both source memory and memory for paired items, with no difference by type of source judgment, and concluded that the difficulty is not specific to self-other distinctions but reflects a broader problem binding the parts of an experience together (Achim & Weiss, 2008).
For testimony, both accounts lead to the same practical questions: whether a disputed detail could have come from another source, such as a conversation, a document, a dream, or the person’s own earlier thoughts about the event, and whether there is a record that bears on when the detail first appeared.
Confidence in Memory Errors
A recurring finding in this literature concerns metacognition, a person’s judgment of how good his or her own memory is. In a source-monitoring study with 30 participants with schizophrenia and 21 comparison participants, the group with schizophrenia made more source errors and was more confident than comparison participants that mistaken source attributions were correct; in that study the bias was smaller among participants taking higher doses of antipsychotic medication (Moritz et al., 2003). A follow-up study found that participants with schizophrenia held a higher proportion of their high-confidence responses in error (Moritz et al., 2005). The authors proposed that confident errors may contribute to the fixed false beliefs that characterize delusions, a hypothesis rather than an established mechanism.
A scoping review of clinical and nonclinical research linked delusional thinking, rather than general memory ability, to errors of commission (false alarms and intrusions), source memory biases, and impaired metamemory, and proposed that these tendencies become more prominent during acute psychosis (Koller & Cannon, 2023). Confidence expressed after repeated questioning or exposure to other information is a weak guide to accuracy for any witness (see Confidence and Accuracy), and the link may be weaker still for some people with schizophrenia, particularly during periods of active delusional thinking. It does not suggest that their confident statements are generally wrong.
False Memory and Suggestibility
One might expect these findings to produce high rates of false memory, but the laboratory evidence is more mixed. A review concluded that neither general memory impairment nor false memories reliably distinguish people with schizophrenia or delusions from psychiatric comparison groups, and that the more distinctive feature is reduced awareness of one’s own memory errors (Moritz & Woodward, 2006). In a word-list study of adults with stabilized schizophrenia, participants recalled and recognized fewer studied words than comparison participants, but their rate of false memories for related, unpresented words was neither higher nor lower (Robin et al., 2023). The suggestion paradigm closest to witness settings has been tested only recently, in a single study: using a procedure in which co-witnesses unknowingly viewed different versions of a crime event, Shinde and Kumar (2025) reported that participants with schizophrenia were no more susceptible to co-witness misinformation than participants without psychiatric illness. The published summary does not report the sample size, and the finding has not yet been replicated, so it is best treated as preliminary.
These findings do not support an assumption that witnesses with schizophrenia are generally more suggestible or more prone to false memories than other witnesses. Nor do they show that suggestion is harmless for them; misinformation affects everyone (see The Misinformation Effect), and source-monitoring difficulty combined with confident errors is a reason to protect the account through careful interviewing and documentation.
Witnesses and Accused Persons with Schizophrenia
Many people with schizophrenia give accurate accounts. The illness is episodic and varies across people, and symptoms, medication, substance use, and stress can all affect cognition. The inquiry is individual: how the person functioned when the events occurred and when the account was given, whether the account concerns perceived events or matters plausibly connected to delusional content, how it was elicited, and what independent evidence bears on it. Delusional beliefs are typically specific in content; their presence does not make unrelated observations unreliable, and the absence of a delusion about the event does not make an account accurate.
The diagnosis can itself become a source of error. Discounting an account because the witness has schizophrenia is not supported by the memory research, and neither is crediting an account that has not been tested. Person-first language, such as “a witness with schizophrenia” rather than “a schizophrenic,” reflects the point that the diagnosis is one fact about the person, not the measure of his or her evidence, and it helps keep stigma out of the courtroom.
For accused persons, the same processes bear on statements to investigators, recollection of the events, and the ability to assist counsel; interrogation and suspect suggestibility are addressed in the False Confessions resources. Competence to stand trial and mental responsibility are decided under separate legal standards, discussed below, which memory research informs but does not answer.
Limits of the Evidence
Most of this research compares groups of outpatients or inpatients with comparison groups on word lists, pictures, or self-generated associations, with samples often of 20 to 60 people per group. Few studies examine memory for complex, emotionally significant events, and only one located study used a witness paradigm. Samples differ in symptoms, medication, illness duration, and co-occurring conditions, and many studies cannot separate the illness from medication, substance use, or reduced motivation during testing. Effect sizes describe average group differences with substantial overlap. Group research cannot determine whether a particular person’s memory of a particular event is accurate, or support inferring accuracy or inaccuracy from the diagnosis.
Questions to Ask About This Research
When the Aleman et al. (1999) meta-analysis is cited for a large memory impairment, counsel should ask what was measured: completeness of recall and recognition of laboratory material, not the accuracy of accounts of real events. When source-monitoring research such as Damiani et al. (2022) is offered to suggest that a witness confused imagination with reality, counsel should ask whether the disputed content is the kind those studies tested, whether there is any evidence of an alternative source for the detail, and whether the competing meta-analytic view (Achim & Weiss, 2008) has been acknowledged. When confidence findings (Moritz et al., 2003, 2005) are used to discount a confident witness, counsel should ask how many participants were studied, whether the witness was experiencing active delusional thinking at the relevant time, and whether the confidence at issue was expressed at the first account or after later questioning. When a witness with schizophrenia is said to be especially suggestible, counsel should ask what study shows that, given Robin et al. (2023) and Shinde and Kumar (2025); when Shinde and Kumar is offered to show the opposite, counsel should ask how many people it tested and whether it has been replicated. These questions are explained in “Reading Research Claims: A Guide for Attorneys” on this site.
Schizophrenia, Memory, and the Law
Federal and Military Standards
Federal Rule of Evidence 601 and Military Rule of Evidence 601 provide that every person is competent to be a witness unless the rules provide otherwise; a psychiatric diagnosis does not disqualify a witness, and questions about a witness’s capacity to perceive and remember are ordinarily matters for cross-examination and weight. Expert testimony on memory in schizophrenia is governed by Federal Rule of Evidence 702, as amended December 1, 2023, which requires the proponent to show that it is more likely than not that the testimony rests on sufficient facts or data and reflects a reliable application of reliable methods. Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) and Kumho Tire Co. v. Carmichael (1999) extend that gatekeeping obligation to all expert testimony, including non-scientific specialized knowledge. In courts-martial, admissibility is assessed under Military Rule of Evidence 702 and the factors of United States v. Houser (1993); the 2023 federal amendment took effect in the military rule in 2025 through Military Rule of Evidence 1102 (Joint Service Committee on Military Justice, 2025), and practitioners should confirm current text. A witness’s mental health records may be privileged under Military Rule of Evidence 513, subject to its exceptions and procedures.
For an accused person, competence to stand trial requires a sufficient present ability to consult with counsel with a reasonable degree of rational understanding and a rational and factual understanding of the proceedings (Dusky v. United States, 1960); in courts-martial, Rule for Courts-Martial 909 presumes capacity and bars trial of an accused who, because of a mental disease or defect, cannot understand the proceedings or cooperate intelligently in the defense. Under Rule for Courts-Martial 916(k), lack of mental responsibility is an affirmative defense and a lesser mental condition is not, although evidence of such a condition may be admissible on whether the accused had a required state of mind (see Observation Evidence and Mental State).
Arizona
Arizona Rule of Evidence 601 and A.R.S. § 13-4061 provide that every person is competent to be a witness in a criminal trial. Arizona Rule of Evidence 702 adopted the Daubert standard effective January 1, 2012, and was amended effective January 1, 2024, to track the 2023 federal amendment (Ariz. Sup. Ct. Order R-23-0004). State v. Chapple (1983), Arizona’s leading case on expert testimony about memory and eyewitness reliability, held exclusion of such testimony an abuse of discretion on its facts; admission otherwise rests in the trial court’s discretion, and State v. Nordstrom (2001) approved limiting an expert to general factors without an opinion on the accuracy of a particular witness. Under State v. Lindsey (1986) and State v. Moran (1986), no expert may opine on the accuracy, reliability, or credibility of a particular witness, which applies equally to testimony that a witness with schizophrenia is or is not reliable. When a defendant seeks a victim’s privileged mental health records, in camera review requires a sufficiently specific showing of a reasonable possibility that the records contain information to which the defendant is constitutionally entitled (R.S. v. Thompson, 2021, ¶ 30).
For accused persons, competence to stand trial is addressed under Arizona Rule of Criminal Procedure 11 and A.R.S. §§ 13-4501 et seq. Arizona’s guilty-except-insane defense is defined in A.R.S. § 13-502. In State v. Mott (1997), the Arizona Supreme Court held that expert evidence of a mental disorder short of insanity is not admissible to negate mens rea, and Clark v. Arizona (2006) upheld that rule while recognizing that observation evidence of a defendant’s behavior remains available on mens rea. In Arizona, therefore, evidence that schizophrenia affected an accused person’s mental state at the time of the offense ordinarily belongs to the insanity defense, while memory testimony about the reliability of later accounts is a separate question.
Special Issues in Legal Practice
The principles described above apply with equal force to every party in a legal proceeding. The science operates the same way regardless of who is asking the questions, and the research summarized here does not by itself favor either side. What differs between the parties is not the science but the vantage point — the particular places where these issues tend to surface, and the particular errors each party is best positioned to guard against. The two summaries below identify those recurring issues. They are offered for orientation, not as litigation strategy; in every case the controlling question is what the evidence in that case will, and will not, support, and the expert’s role is to inform the trier of fact rather than to advocate for either side.
Special Issues for Prosecutors
The research supports several propositions prosecutors can legitimately present. A diagnosis of schizophrenia does not make a witness incompetent or an account unreliable, and people with serious mental illness are victimized at high rates. Memory differences in schizophrenia appear largely as reduced completeness, especially in free recall, rather than as invented events; laboratory false-memory rates are often similar to those of comparison groups, and a single, not yet replicated witness-paradigm study found no greater susceptibility to co-witness misinformation. Prosecutors are well positioned to protect the value of such a witness’s account by recording an early free narrative, using open-ended questions, noting the person’s clinical condition at the time of the account, and documenting what information the witness was given.
The research also counsels caution. Source-monitoring difficulties and confidence in mistaken source judgments are documented at the group level, and a witness’s certainty is not a reliable substitute for corroboration, particularly for content that could be connected to delusional beliefs or to information heard from others. An expert’s general testimony that a witness group is accurate may not become an opinion that this witness is accurate (Lindsey). An accused person’s statements to investigators may likewise reflect source confusion or confident error and should be compared with what the person was told.
Special Issues for Defense
The research supports several propositions defense counsel can legitimately present. On average, people with schizophrenia show weaker encoding, more source-monitoring errors, particularly for internally generated material, and, in studies from one research group, greater confidence in mistaken source judgments. Where a disputed detail could have originated in another source or in the person’s own thoughts, and where there is evidence of the person’s condition at the relevant time, expert testimony explaining these processes can help the factfinder evaluate the account, including an accused person’s own statements.
The research also counsels caution about the limits that apply to the defense. The diagnosis does not show that an account is inaccurate, the false-memory findings are mixed, and many people with schizophrenia perform within the range of comparison groups. An expert may not testify that a particular witness’s memory is false, and arguments that rest on the diagnosis alone invite stigma rather than analysis. Requests for a witness’s mental health records require a specific basis under the governing rules. In Arizona, Mott limits the use of mental-disorder evidence to negate mens rea, so testimony about an accused person’s illness must be directed to a permitted purpose.
This paper is for educational purposes only and is not legal advice. The author is a psychologist, not an attorney; summaries of law are general and must be verified against current authority or with a licensed attorney.
References
Achim, A. M., & Weiss, A. P. (2008). No evidence for a differential deficit of reality monitoring in schizophrenia: A meta-analysis of the associative memory literature. Cognitive Neuropsychiatry, 13(5), 369–384. https://doi.org/10.1080/13546800802299476
Aleman, A., Hijman, R., de Haan, E. H. F., & Kahn, R. S. (1999). Memory impairment in schizophrenia: A meta-analysis. American Journal of Psychiatry, 156(9), 1358–1366. https://doi.org/10.1176/ajp.156.9.1358
Brébion, G., Amador, X., Smith, M. J., & Gorman, J. M. (1997). Mechanisms underlying memory impairment in schizophrenia. Psychological Medicine, 27(2), 383–393. https://doi.org/10.1017/S0033291796004448
Damiani, S., Donadeo, A., Bassetti, N., Salazar-de-Pablo, G., Guiot, C., Politi, P., & Fusar-Poli, P. (2022). Understanding source monitoring subtypes and their relation to psychosis: A systematic review and meta-analysis. Psychiatry and Clinical Neurosciences, 76(5), 162–171. https://doi.org/10.1111/pcn.13338
Johnson, M. K., Hashtroudi, S., & Lindsay, D. S. (1993). Source monitoring. Psychological Bulletin, 114(1), 3–28. https://doi.org/10.1037/0033-2909.114.1.3
Joint Service Committee on Military Justice. (2025). Amendments to the Military Rules of Evidence since 1984 (G. E. Maggs, Ed.; 2025 ed.). https://jsc.defense.gov/Portals/99/MRE%20Amendments%202025.pdf
Koller, W. N., & Cannon, T. D. (2023). Aberrant memory and delusional ideation: A pernicious partnership? Clinical Psychology Review, 99, Article 102231. https://doi.org/10.1016/j.cpr.2022.102231
Moritz, S., & Woodward, T. S. (2006). Metacognitive control over false memories: A key determinant of delusional thinking. Current Psychiatry Reports, 8(3), 184–190. https://doi.org/10.1007/s11920-006-0022-2
Moritz, S., Woodward, T. S., & Ruff, C. C. (2003). Source monitoring and memory confidence in schizophrenia. Psychological Medicine, 33(1), 131–139. https://doi.org/10.1017/S0033291702006852
Moritz, S., Woodward, T. S., Whitman, J. C., & Cuttler, C. (2005). Confidence in errors as a possible basis for delusions in schizophrenia. Journal of Nervous and Mental Disease, 193(1), 9–16. https://doi.org/10.1097/01.nmd.0000149213.10692.00
Robin, F., Salomé, F., & El Haj, M. (2023). False memories in individuals with stabilized schizophrenia. Psychological Reports, 126(5), 2119–2140. https://doi.org/10.1177/00332941221083213
Shinde, A., & Kumar, D. (2025). When an individual with schizophrenia has co-witnessed a crime: Exploring memory conformity for crime event in schizophrenia. Asian Journal of Psychiatry, 113, Article 104726. https://doi.org/10.1016/j.ajp.2025.104726
Teplin, L. A., McClelland, G. M., Abram, K. M., & Weiner, D. A. (2005). Crime victimization in adults with severe mental illness: Comparison with the National Crime Victimization Survey. Archives of General Psychiatry, 62(8), 911–921. https://doi.org/10.1001/archpsyc.62.8.911
Legal Authorities
Clark v. Arizona, 548 U.S. 735 (2006).
Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).
Dusky v. United States, 362 U.S. 402 (1960).
Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999).
R.S. v. Thompson, 251 Ariz. 111, 485 P.3d 1068 (2021).
State v. Chapple, 135 Ariz. 281, 660 P.2d 1208 (1983).
State v. Lindsey, 149 Ariz. 472, 720 P.2d 73 (1986).
State v. Moran, 151 Ariz. 378, 728 P.2d 248 (1986).
State v. Mott, 187 Ariz. 536, 931 P.2d 1046 (1997).
State v. Nordstrom, 200 Ariz. 229, 25 P.3d 717 (2001).
United States v. Houser, 36 M.J. 392 (C.M.A. 1993).
Ariz. Rev. Stat. Ann. § 13-502.
Ariz. Rev. Stat. Ann. § 13-4061.
Ariz. Rev. Stat. Ann. §§ 13-4501 et seq.
Fed. R. Evid. 601.
Fed. R. Evid. 702.
Ariz. R. Evid. 601.
Ariz. R. Evid. 702.
Ariz. Sup. Ct. Order R-23-0004 (amending Ariz. R. Evid. 702, effective Jan. 1, 2024).
Ariz. R. Crim. P. 11.
Mil. R. Evid. 513.
Mil. R. Evid. 601.
Mil. R. Evid. 702.
Mil. R. Evid. 1102.
Rule for Courts-Martial 909.
Rule for Courts-Martial 916(k).
Related topic papers: Memory in Special Populations · Source Monitoring · Confidence and Accuracy · False Memory · The Misinformation Effect · Observation Evidence and Mental State
Related topics from Arizona Forensic Services: False Confessions: Suggestibility · Courts-Martial