Fading Affect Bias – Arizona Forensic Services, LLC

Snap Shot

The question: Does the emotion attached to a memory change over time, and what does that mean for a witness’s demeanor and recalled distress when an account is given months or years after the event?

What the research shows: In most people, the unpleasant feeling attached to negative memories fades faster than the pleasant feeling attached to positive memories. The pattern begins within hours of an event, has been found in many cultures, and is generally stronger in psychologically healthy people. It is reduced in people with depressive symptoms, anxiety, or posttraumatic stress symptoms, and memories of serious losses fade less than everyday negative memories.

What it does not show: The fading affect bias concerns feeling, not factual accuracy. It does not show that a calm witness experienced a minor event, that a distressed witness is exaggerating, or that any particular account is accurate or inaccurate.

The law: Expert testimony is governed by Rule 702, Houser, and Chapple; general testimony about memory and emotion is permitted in appropriate cases, but an expert may not opine on a particular witness’s credibility (Lindsey).

Issues for each side: Prosecutors can explain that composed testimony long after an event is common and does not by itself indicate that little happened; defense counsel can explain that present emotion, strong or faint, is a poor measure of what happened, without suggesting that persistent distress signals exaggeration.

When people recall events from their own lives, the feelings that accompany the memories change over time. For most people, the sting of an unpleasant memory diminishes faster than the warmth of a pleasant one. Researchers call this asymmetry the fading affect bias. It has been replicated many times in studies of ordinary autobiographical memory, and researchers generally regard it as part of healthy emotional adjustment.

The finding reaches court because jurors and others often treat how upset a witness appears now as an index of what happened. A complainant who testifies calmly about an assault that occurred a year or more earlier may be thought to have experienced something less serious, or to be giving a false account; a witness who remains distressed may be thought to be exaggerating. Research on emotional fading bears on both assumptions. Because the bias concerns emotion rather than content, it also bears on what demeanor cannot show about accuracy.

This paper describes the research on the fading affect bias, how quickly it appears, why it is thought to occur, the conditions under which it is reduced, and its implications for delayed accounts and demeanor. It then reviews the limits of the evidence, the law governing expert testimony, and recurring issues for each side. A companion paper, Rosy Retrospection, addresses the related tendency to evaluate past experiences more favorably over time.

What the Fading Affect Bias Is

In a typical study, participants recall or record positive and negative events and rate how pleasant or unpleasant each felt when it happened; later, they rate how it feels to remember the event now. In an early diary study, the unpleasant affect of negative events faded more than the pleasant affect of positive events over the retention interval (Walker et al., 1997). Reviews of the research since then describe the effect as robust across methods, including diaries and retrospective recall, and across samples (Skowronski et al., 2014; Walker & Skowronski, 2009). In a study of more than 2,400 event descriptions from 562 participants in ten cultures, each sample showed the bias (Ritchie et al., 2015).

The bias concerns affect, the emotional charge of a memory. It does not describe whether the memory’s content is accurate or complete. A person may remember what happened in detail while the feeling that accompanied the event has substantially diminished, and a person may retain strong feelings about an event whose details have faded. The research measures people’s ratings of emotional intensity; it does not test the accuracy of the events recalled.

Negative emotion does not vanish. The bias is a difference in the rate of fading, and in most studies negative memories continue to carry some unpleasant feeling at the later rating. The strength of the effect also differs across kinds of events. In a community study conducted in Mexico, memories of the death of a loved one showed fading, but less fading than everyday negative memories (Bond et al., 2022).

How Quickly It Appears

Early research examined events weeks or years old. Later analyses found that the bias was already present within 12 hours of an event and persisted across three months (Gibbons et al., 2011). The differential fading of negative affect is therefore not only a long-term mellowing of distant memories but a process that begins soon after an event. For legal purposes, this means that by the time of a first formal interview, let alone a trial, the emotional intensity a person feels when recounting a negative event may already differ from what the person felt when it occurred.

Why It Is Thought to Occur

Researchers have proposed that the fading affect bias supports emotional well-being by allowing people to move past negative experiences while retaining the positive feeling of good ones, which helps maintain a favorable view of one’s own life (Walker, Skowronski, & Thompson, 2003; Walker & Skowronski, 2009). Rehearsal appears to matter: how often and in what way people think and talk about an event is associated with how its emotional intensity changes, and reviews describe social disclosure as generally associated with greater fading of negative affect (Skowronski et al., 2014). The bias was stronger among older participants in two age-diverse community samples, a finding the authors related to the emphasis on emotion regulation in later life (Marsh & Crawford, 2024). These explanations are interpretations of correlational and experimental findings, and the mechanisms are not fully settled.

When the Bias Is Reduced

The exceptions are as important for legal purposes as the general rule. In a study comparing participants with and without dysphoria, a mildly depressed mood, dysphoria disrupted the usual pattern, reducing or eliminating the faster fading of negative affect (Walker, Skowronski, Gibbons, et al., 2003). In a study of 296 participants, higher depressive symptoms were associated with less fading for both negative and positive memories, and the link for negative memories ran partly through a greater tendency to think about negative events (Marsh et al., 2019). Across three studies, higher trait anxiety was associated with a smaller bias and with less fading of both positive and negative affect (Walker et al., 2014).

Trauma raises the clearest exception. Posttraumatic stress disorder is defined in part by recurrent, involuntary, and distressing memories of the traumatic event and by intense distress when reminded of it (American Psychiatric Association, 2022), so persistent negative emotion is a recognized feature of the disorder rather than an anomaly. Direct research on the fading affect bias in trauma survivors is limited, but in the Mexican community study, participants with more posttraumatic stress symptoms showed less fading of affect across all their memories (Bond et al., 2022). Persistent, intense distress about a past event is therefore consistent with known patterns of memory and emotion, and it is not, by itself, a sign of exaggeration. Equally, persistent distress does not establish that a particular event occurred as described, because these studies measure feeling, not accuracy.

Implications for Delayed Accounts and Demeanor

Accounts in criminal cases are often given long after the event: a report may come some time after the event, investigations take time, and trials may occur a year or more after the first report. The fading affect bias suggests that a person who experienced a distressing event will often, though not always, feel less intense emotion when recounting it later than when it occurred. A composed demeanor at a later interview or at trial is therefore common and, by itself, is a weak indicator of how distressing the event was. The same research means that a person’s present report of how upset he or she was at the time is a retrospective rating that may itself have shifted.

Demeanor nonetheless affects judgments of credibility. In an experiment in which participants viewed a video of an actress portraying a rape complainant, credibility judgments were strongly influenced by the emotion displayed and not by the strength of the account, and a neutral or incongruent demeanor reduced perceived credibility, although story content and displayed emotion contributed about equally to estimates of the likelihood of a guilty verdict (Kaufmann et al., 2003). In a study of 189 police trainees, a more emotional complainant demeanor increased perceived credibility, an “emotional victim effect” that was explained both by violated expectations and by observers’ compassionate reactions (Ask & Landström, 2010). These studies show that people rely on demeanor; they do not show that demeanor is a valid guide to accuracy. Demeanor, whether calm or distressed, does not by itself indicate whether an account is accurate; that is why the research points to records and procedures. Taken together with the fading affect bias, they suggest that expectations about how a genuine complainant should appear, months or years later, may not match how emotion changes over time.

The research applies in the same way to the accused and to other witnesses. An accused person who describes an angry confrontation calmly at trial, or a witness who recounts a frightening event without visible distress, is showing the same ordinary change in feeling.

Limits of the Evidence

Most fading affect research uses college students or community volunteers who choose which events to report, and most events are everyday experiences rather than crimes. Emotional intensity at the time of the event is usually rated retrospectively, so the measure of initial emotion is itself a memory. The studies of trauma and of serious losses are few, and the posttraumatic stress finding comes from a single community sample. The research measures self-reported feeling, not demeanor observed by others, and the link between felt emotion and displayed emotion in a courtroom has not been studied directly in this literature. Group findings cannot establish how a particular witness felt at the time, why a particular witness appears calm or distressed, or whether a particular account is accurate.

Questions to Ask About This Research

If the research on emotional fading (Walker et al., 1997; Skowronski et al., 2014) is offered to account for a complainant’s composure on the stand, counsel can ask what exactly was measured: participants’ ratings of emotional intensity at the event and at recall, usually for everyday events, not observed courtroom demeanor or the accuracy of an account. When the research is used to argue that a calm witness experienced a minor event, or that a distressed witness is exaggerating, counsel can ask whether the conclusion follows from the design, because the studies show that fading varies with mood, anxiety, posttraumatic symptoms, and the kind of event (Bond et al., 2022; Marsh et al., 2019). When Gibbons et al. (2011) is relied on for the speed of fading, counsel can ask whether the events studied are comparable to the event in the case. When the demeanor studies (Kaufmann et al., 2003; Ask & Landström, 2010) are cited, counsel can ask who was studied and under what conditions, since the participants viewed actors or vignettes rather than real testimony. In each instance, counsel can ask whether a group tendency applies to this person. These questions are explained in “Reading Research Claims: A Guide for Attorneys” on this site.

Fading Affect Bias and the Law

Federal and Military Standards

Expert testimony about memory and emotion is governed by Federal Rule of Evidence 702, as amended December 1, 2023, under which the proponent must show that it is more likely than not that the rule’s requirements are met, including a reliable application of reliable principles and methods to the case. Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) made the trial judge a gatekeeper, 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, 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; admissibility is assessed under the six factors of United States v. Houser (1993). Testimony about demeanor and emotional fading is general in nature; an expert may explain the research but may not tell the members or jury that a particular witness’s demeanor shows that the witness is truthful or untruthful.

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 about memory and eyewitness reliability; excluding such testimony was an abuse of discretion on its facts, and admission otherwise remains within the trial court’s discretion, with the expert permissibly limited to general factors (State v. Nordstrom, 2001). Arizona permits general, educational testimony by an expert who has not evaluated the witness, if it satisfies Rule 702 and Rule 403 (State v. Salazar-Mercado, 2014), and prohibits expert testimony about whether a particular witness is truthful (State v. Lindsey, 1986, 149 Ariz. at 475).

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. The unpleasant feeling attached to negative memories commonly fades over time, beginning soon after an event, so a complainant who testifies calmly long after an assault is showing an ordinary pattern, and calm demeanor does not by itself indicate that the event was minor or did not occur. Persistent distress is also consistent with known patterns, particularly in people with depressive or posttraumatic symptoms. Research showing that observers rely on demeanor in judging complainants supports general testimony explaining why demeanor does not by itself indicate accuracy, and prosecutors are well positioned to build the case on what the account says and on corroborating evidence, not on how the complainant appears.

The research also counsels caution. Fading affect research measures feeling, not accuracy, so it cannot support an argument that a complainant’s account is accurate, and testimony that presents persistent distress as confirming that an event occurred goes beyond the research. A complainant’s present description of how distressed he or she was at the time is a retrospective rating that may have shifted. The same principles apply to the accused and defense witnesses, whose calm or emotional demeanor is equally uninformative about truthfulness.

Special Issues for Defense

The research supports several propositions defense counsel can legitimately present. Present emotion, calm or distressed, is not a reliable measure of what happened in the past: felt and displayed emotion can reflect mood, anxiety, and rehearsal as well as the event itself, although the link between felt and displayed emotion in court has not been studied directly in this research, and a person’s recollection of how much he or she suffered is itself a memory that can change with time and mood. General testimony on these points can help the factfinder avoid treating vivid emotion as corroboration. Where a claim of emotional harm is in issue, the time elapsed and the course of disclosure bear on how recalled distress should be weighed, and mental-health history may bear on it in either direction (for example, depressive or posttraumatic symptoms reduce fading).

The research also counsels caution about the limits that apply to the defense. Fading affect research does not support arguments that a calm complainant experienced a minor event or fabricated one, or that intense, persistent distress indicates exaggeration or malingering; persistent distress is consistent with depressive and posttraumatic conditions. An expert cannot tell the factfinder that a particular witness’s demeanor shows truthfulness or untruthfulness. The accused’s own calm or emotional presentation is subject to the same principles.

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

American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.). https://doi.org/10.1176/appi.books.9780890425787

Ask, K., & Landström, S. (2010). Why emotions matter: Expectancy violation and affective response mediate the emotional victim effect. Law and Human Behavior, 34(5), 392–401. https://doi.org/10.1007/s10979-009-9208-6

Bond, G. D., Speller, L. F., Jiménez, J. C., Smith, D., Marin, P. G., Greenham, M. B., Holman, R. D., & Varela, E. (2022). Fading affect bias in Mexico: Differential fading of emotional intensity in death memories and everyday negative memories. Applied Cognitive Psychology, 36(5), 1022–1033. https://doi.org/10.1002/acp.3987

Gibbons, J. A., Lee, S. A., & Walker, W. R. (2011). The fading affect bias begins within 12 hours and persists for 3 months. Applied Cognitive Psychology, 25(4), 663–672. https://doi.org/10.1002/acp.1738

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

Kaufmann, G., Drevland, G. C. B., Wessel, E., Overskeid, G., & Magnussen, S. (2003). The importance of being earnest: Displayed emotions and witness credibility. Applied Cognitive Psychology, 17(1), 21–34. https://doi.org/10.1002/acp.842

Marsh, C., & Crawford, M. T. (2024). Age is positively associated with fading affect bias: A cross-sectional comparison. Psychology and Aging, 39(2), 139–152. https://doi.org/10.1037/pag0000797

Marsh, C., Hammond, M. D., & Crawford, M. T. (2019). Thinking about negative life events as a mediator between depression and fading affect bias. PLOS ONE, 14(1), Article e0211147. https://doi.org/10.1371/journal.pone.0211147

Ritchie, T. D., Batteson, T. J., Bohn, A., Crawford, M. T., Ferguson, G. V., Schrauf, R. W., Vogl, R. J., & Walker, W. R. (2015). A pancultural perspective on the fading affect bias in autobiographical memory. Memory, 23(2), 278–290. https://doi.org/10.1080/09658211.2014.884138

Skowronski, J. J., Walker, W. R., Henderson, D. X., & Bond, G. D. (2014). The fading affect bias: Its history, its implications, and its future. Advances in Experimental Social Psychology, 49, 163–218. https://doi.org/10.1016/B978-0-12-800052-6.00003-2

Walker, W. R., & Skowronski, J. J. (2009). The fading affect bias: But what the hell is it for? Applied Cognitive Psychology, 23(8), 1122–1136. https://doi.org/10.1002/acp.1614

Walker, W. R., Skowronski, J. J., Gibbons, J. A., Vogl, R. J., & Thompson, C. P. (2003). On the emotions that accompany autobiographical memories: Dysphoria disrupts the fading affect bias. Cognition and Emotion, 17(5), 703–723. https://doi.org/10.1080/02699930302287

Walker, W. R., Skowronski, J. J., & Thompson, C. P. (2003). Life is pleasant—and memory helps to keep it that way! Review of General Psychology, 7(2), 203–210. https://doi.org/10.1037/1089-2680.7.2.203

Walker, W. R., Vogl, R. J., & Thompson, C. P. (1997). Autobiographical memory: Unpleasantness fades faster than pleasantness over time. Applied Cognitive Psychology, 11(5), 399–413. https://doi.org/10.1002/(SICI)1099-0720(199710)11:5<399::AID-ACP462>3.0.CO;2-E

Walker, W. R., Yancu, C. N., & Skowronski, J. J. (2014). Trait anxiety reduces affective fading for both positive and negative autobiographical memories. Advances in Cognitive Psychology, 10(3), 81–89. https://doi.org/10.5709/acp-0159-0

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).

State v. Salazar-Mercado, 234 Ariz. 590, 325 P.3d 996 (2014).

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).

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