Snap Shot
- The question: Do people involved in a disputed event explain and remember their own conduct in ways that protect their self-image, and how should that affect the evaluation of their accounts?
- What the research shows: People generally attribute their successes to themselves and their failures to circumstances, a large and pervasive effect in a meta-analysis of 266 studies. People also tend to forget unflattering feedback about themselves, to remember their past performance and conduct as better than it was, and to retell a conflict in ways that favor their own role; participants who retold a story as its victim or its perpetrator distorted it to about the same extent.
- What it does not show: The bias is a group tendency that varies with culture, age, mental health, and relationship, and it is much smaller in depression. It does not show that any particular witness has shaded an account, and memory error that serves the self is not lying. Most studies use attributions for success and failure, laboratory feedback, or retold stories, not memory for contested criminal events.
- The law: Expert testimony on the bias must satisfy Rule 702 and, in courts-martial, Houser; Arizona permits general memory testimony (Chapple, Nordstrom) but no expert may opine that a particular witness is or is not truthful (Lindsey).
- Issues for each side: Prosecutors can explain why an accused may sincerely remember his or her own conduct as more reasonable than it was, but must recognize that the same research applies to complainants and government witnesses; defense counsel can explain why a complainant’s or co-participant’s allocation of blame warrants testing against independent evidence, but must recognize that the research applies equally to the accused.
The self-serving bias is the tendency to see and remember one’s own conduct in a way that protects or enhances self-image: to credit oneself for good outcomes, to locate the causes of bad outcomes in other people or circumstances, and to remember the past in a more flattering light than the record supports. The bias is among the most thoroughly documented findings in social psychology, and it is usually sincere. A person whose account has been shaped by it generally believes the account.
The bias reaches court because people who were involved in a disputed event, including complainants, accused persons, co-participants, and civil parties, are asked to describe what they did and why. Each has a self-image at stake, and the research predicts that each will tend to frame and remember the event in a way that favors his or her own role. The research applies symmetrically, and it does not convert self-favoring memory into evidence of deception.
This paper summarizes the research on the attributional self-serving bias, mnemic neglect (the selective forgetting of unflattering information about oneself), self-enhancement in memory, and motivated memory in disputes, followed by the limits of the evidence and the governing law. Egocentric Bias, which concerns the greater availability of one’s own actions and perspective, and The Self-Reference Effect, which concerns why self-relevant information is remembered well, are addressed in their own papers.
The Attributional Self-Serving Bias
Miller and Ross (1975) reviewed the early evidence that people take credit for success and deny responsibility for failure and asked whether the pattern reflected motivation to protect the self or ordinary information processing, such as the expectation of success. That question has not been fully resolved, and current accounts hold that both motivational and cognitive processes contribute (Shepperd et al., 2008). The size and generality of the pattern are better settled. A meta-analysis of 266 studies, yielding 503 effect sizes, found that people made more internal, stable, and global attributions for positive events than for negative events, with an average effect size of d = 0.96, and that the bias was present in nearly all samples (Mezulis et al., 2004).
The same meta-analysis found substantial variation. The bias was largest in children and older adults, smaller in Asian samples (d = 0.30) than in U.S. samples (d = 1.05), and markedly attenuated in samples with psychopathology (d = 0.48), particularly depression (d = 0.21), compared with samples without psychopathology (d = 1.28) (Mezulis et al., 2004). Another meta-analysis found that the bias grows when the self is threatened (Campbell & Sedikides, 1999), and experimental work found that it is reduced between people in close relationships, who extend to each other some of the credit they give themselves (Sedikides et al., 1998).
A related claim is often stated too broadly. The actor-observer hypothesis holds that people explain their own behavior by circumstances and others’ behavior by personality. A meta-analysis of 173 studies found that, across positive and negative events, the average asymmetry was close to zero; it appeared for negative events and reversed for positive events, a pattern that may reflect self-serving attribution rather than a general difference between actors and observers (Malle, 2006). The more accurate statement for court is that people tend to explain their own negative acts by circumstances, not that actors and observers generally see events differently.
Mnemic Neglect: Forgetting Unflattering Information
Self-serving processes affect what is remembered, not only how it is explained. In the mnemic neglect paradigm, participants read feedback describing behaviors that reflect positively or negatively on central traits, such as honesty or kindness, either as feedback about themselves or as feedback about another person. Participants later recalled fewer of the negative behaviors when the feedback concerned themselves than when it concerned another person, while recall of positive behaviors did not show the same deficit (Sedikides & Green, 2000). The effect has been attributed to shallower processing of threatening self-relevant information at encoding, and it is reduced when the feedback concerns peripheral rather than central traits or when the person is focused on self-improvement (Sedikides & Green, 2009; Sedikides et al., 2016).
A 2025 meta-analysis of 18 studies (93 independent samples, N = 4,989) found that the mnemic neglect effect was reliable but modest in size (g = 0.37), that participants recalled fewer central negative items about themselves than about another person, and that the effect varied with anxiety and with the kind of trait involved (Liu et al., 2025). A cross-cultural study found the effect in both American and Chinese participants, with no indication that it was larger among Americans (Tan et al., 2026). The paradigm uses written feedback about hypothetical behaviors, not memory for one’s own conduct in a real event.
Self-Enhancement in Memory
A recent review of the self-memory system groups self-enhancing bias with consistency bias and positivity bias as forms of distortion in which current goals and beliefs shape memory for the past, and it emphasizes that such biases can serve adaptive functions while also producing error (Schacter et al., 2024). Several studies show the pattern in verified records. College students who recalled their high school grades, checked against transcripts, were accurate for 89% of A grades but only 29% of D grades, and most errors inflated the grade (Bahrick et al., 1996). Across five experiments (N = 3,190), people recalled having been more generous in an economic game than they had actually been, even when paid for accurate recall; the effect appeared chiefly in people whose choices fell short of their own fairness standards and disappeared when they were not responsible for the outcome (Carlson et al., 2020). In a field study of managers who took part repeatedly in a firm’s tournament incentive system and learned their relative performance each time, managers remembered their past performance as better than it had been, and those overly positive memories were linked to their overconfident predictions (Huffman et al., 2022).
These findings show that memory for one’s own conduct can drift in a self-favoring direction while remaining sincere, and that the drift is greatest where the conduct conflicts with the person’s own standards. They do not show how large the drift is for a vivid, consequential event, and in the grades study accuracy was highest for the grades that reflected best on the students.
Motivated Memory in Disputes
The bias has been studied directly in legal and quasi-legal disputes. In bargaining experiments with undergraduates and law students, based on a motor vehicle accident case, participants assigned to the role of plaintiff or defendant read the same case materials, yet each side’s estimate of a fair settlement, and its prediction of what a judge would award, favored its own side, and the size of the gap predicted failure to settle (Loewenstein et al., 1993). A review of that research program concluded that the bias arises largely from selective evaluation of the same information, that reducing it reduced impasse, and that the same pattern appeared in a field study of teacher contract negotiations (Babcock & Loewenstein, 1997).
Research on the two sides of interpersonal conflict shows that the effect runs in both directions. In autobiographical accounts of everyday conflicts, people describing a time someone angered them tended to portray the provocation as arbitrary and its harm as lasting, while people describing a time they angered someone tended to portray their conduct as understandable and the incident as closed (Baumeister et al., 1990). Those accounts concerned different events, so a follow-up study gave all participants the same story. Participants who identified with the victim or with the perpetrator then retold it; both groups distorted the story to about the same extent, more than control participants, largely by omitting facts that did not suit their role, and the same pattern appeared in a study in which some participants were instructed to be as accurate as possible (Stillwell & Baumeister, 1997). Perpetrators emphasized mitigating circumstances and their own helpful acts; victims emphasized the severity of the offense and downplayed the perpetrator’s positive acts. These studies involved everyday conflicts and assigned roles, not criminal offenses, and the words “victim” and “perpetrator” describe the roles in the study.
The forensic implication is symmetric. An accused person may sincerely remember his or her conduct as more reasonable, more provoked, or less serious than it was. A complainant may sincerely remember the other person’s conduct as more deliberate and his or her own conduct as less involved than it was. Co-participants and others with a stake in how blame is assigned are subject to the same tendencies. In a study of a sexual assault scenario in which participants (total N = 1,341, across three experiments) were assigned the role of complainant or accused, susceptibility to later misinformation did not differ by role (Greene et al., 2025), which suggests that, at least for suggestibility, the role a person occupies does not by itself make that person’s memory more or less reliable. These are laboratory findings (studies of everyday conflicts and a simulated scenario), and they apply equally to accused persons, complainants, and other witnesses. None of this research converts self-favoring memory into evidence that a person is lying, and none of it shows that a particular account is distorted. Deliberate misstatement is a different question, and memory research does not answer it.
Limits of the Evidence
Most self-serving-bias research measures attributions for success and failure, recall of written feedback, or retellings of stories, with student or online participants and low stakes. Field studies of grades, managers, and negotiations show the pattern in real records, but not in memory for a contested criminal event. Effects are averages that vary with culture, age, mental health, anxiety, relationship, and the centrality of the trait threatened, and the bias is much smaller in depression. The research shows that self-favoring distortion is a normal tendency; it cannot show that a particular witness’s account is distorted, in which direction for a particular detail, or by how much. The limits run in the other direction as well: the distortions documented in these studies were concentrated in interpretation, emphasis, omission, and the least flattering items, not in the invention of whole events.
Questions to Ask About This Research
When the meta-analytic effect of d = 0.96 (Mezulis et al., 2004) is cited, counsel should ask what exactly was counted: attributions of positive and negative outcomes to internal or external causes, not the accuracy of memory for specific acts, and the same review found much smaller effects in some cultures and in depression. When mnemic neglect is cited, counsel should ask how large the effect was and in what task, because the 2025 meta-analysis found a modest effect in studies of written feedback (Liu et al., 2025). When Stillwell and Baumeister (1997) is cited to suggest that one party’s account is distorted, counsel should ask whether the same conclusion follows for the other party, because both roles distorted about equally. When the actor-observer difference is offered as established, counsel should ask about the meta-analysis that found it close to zero across events (Malle, 2006). In every case counsel should ask whether the expert is describing a general tendency or offering an opinion about a particular witness. These questions are explained in “Reading Research Claims: A Guide for Attorneys” on this site.
The Self-Serving Bias and the Law
Federal and Military Standards
Expert testimony about memory and attribution is governed by Federal Rule of Evidence 702, as amended December 1, 2023, under which the proponent must show the court that it is more likely than not that the rule’s requirements are met, including that the opinion reflects a reliable application of reliable principles and methods to the facts. Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) assigned the trial judge a gatekeeping role, and Kumho Tire Co. v. Carmichael (1999) extended that obligation to all expert testimony, including testimony based on technical or other specialized knowledge. In courts-martial, Military Rule of Evidence 702 tracks the federal rule, and the 2023 amendment became part of the military rule in 2025 through Military Rule of Evidence 1102 (Joint Service Committee on Military Justice, 2025); practitioners should confirm the current text. Military judges evaluate proffered expert testimony under the six factors of United States v. Houser (1993).
Arizona
Arizona Rule of Evidence 702 adopted the federal formulation and the Daubert standard effective January 1, 2012, and was amended effective January 1, 2024, to conform to the 2023 federal amendment (Ariz. Sup. Ct. Order R-23-0004). State v. Chapple (1983) is Arizona’s leading case on expert testimony concerning the reliability of memory and eyewitness accounts; excluding the expert was an abuse of discretion on its facts, while admission generally remains within the trial court’s discretion, and State v. Nordstrom (2001) approved limiting such an expert to general factors without opinions on the accuracy of a particular witness. Experts may not opine on whether a particular witness is telling the truth (State v. Lindsey, 1986, 149 Ariz. at 475), so testimony about the self-serving bias should describe tendencies rather than vouch for or against a complainant’s, a co-participant’s, or a defendant’s account.
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. People involved in a disputed event tend to explain their own negative conduct by circumstances, to forget unflattering information about themselves, and to remember their own past conduct as better than it was, and these tendencies are strongest when conduct conflicts with the person’s own standards. An accused’s sincere account that minimizes his or her role, or emphasizes provocation or mitigating circumstances, can therefore be inaccurate without being a calculated fabrication. A complainant’s account that differs from the accused’s can result from two people remembering from different roles and is not, by itself, evidence that the complainant is untruthful. Prosecutors are well positioned to secure early statements and contemporaneous records that do not depend on any party’s later framing.
The research also counsels caution. The role-based distortion research found that victims and perpetrators distorted to about the same extent, so testimony that describes the self-serving bias as operating only on the accused misstates it. Complainants, cooperating co-participants, and other government witnesses with a stake in how blame is assigned are subject to the same tendencies, including selective omission of facts that do not fit their role. The bias is a group tendency, weaker in some people and in depression, and it cannot be used to tell the factfinder that the accused’s account is false.
Special Issues for Defense
The research supports several propositions defense counsel can legitimately present. People who identify with one side of a conflict tend to retell it in a way that favors that side, largely by omitting uncongenial facts, and the pattern appeared in a study in which some participants were instructed to be as accurate as possible. In studies of everyday conflicts with assigned roles, people retold a story in ways that favored their role by omitting uncongenial facts; that tendency applies to every participant in a dispute, including complainants, accused persons, and co-participants, and it is a reason to compare any party’s account with independent evidence, not a finding about any particular account. In disputes, people evaluate the same information in ways that favor their own side, so a party’s characterization of shared documents or events is not a neutral reading of them. By the same reasoning, an accused’s account that differs from the complainant’s can result from two people remembering from different roles and is not, by itself, evidence that the accused is untruthful.
The research also counsels caution about the limits that apply to the defense. Self-favoring memory is not lying, and an expert may not tell the factfinder that a complainant’s account is distorted or untrue. The research uses everyday conflicts, assigned roles, and laboratory feedback, not sexual assault or other criminal offenses, and it does not predict which details of a particular account are affected. The accused’s account is subject to the same tendencies, and the research that supports scrutiny of a complainant’s framing supports equal scrutiny of the accused’s.
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
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Legal Authorities
Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).
Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999).
State v. Chapple, 135 Ariz. 281, 660 P.2d 1208 (1983).
State v. Lindsey, 149 Ariz. 472, 720 P.2d 73 (1986).
State v. Nordstrom, 200 Ariz. 229, 25 P.3d 717 (2001).
United States v. Houser, 36 M.J. 392 (C.M.A. 1993).
Fed. R. Evid. 702.
Mil. R. Evid. 702.
Mil. R. Evid. 1102.
Ariz. R. Evid. 702.
Ariz. Sup. Ct. Order R-23-0004 (amending Ariz. R. Evid. 702, effective Jan. 1, 2024).
Related topic papers: Egocentric Bias · The Self-Reference Effect · Hindsight Bias · Consistency Bias · Rosy Retrospection · Confirmation Bias