How Does Negative Emotion Cause False Memories?

1. How Does Negative Emotion Cause False Memories? C. J. Brainerd, L. M. Stein, R. A. Silveira, G. Rohenkohl, & V. F. Reyna Cornell University, Pontifical Catholic University of Rio Grande do Sul , &University of Santa Cruz do Sul

2. Emotion, Memory Distortion, and Memory Evidence in Crimes • The bulk of criminal evidence (investigations & trials) consists of memory reports (e.g., oral interviews, written narratives, telephone conversations, e-mails, eyewitness identifications, interrogations, depositions, trial testimony) • A common feature of such reports is that emotional content is involved: • Criminal events are inherently emotional • Memory reports are often given in circumstances that are fraught with emotion (police interviews, interrogations, sworn testimony) - Hence, whether and how emotional content distorts memory is a fundamental question when it comes to the reliability of evidence

3. Basic Scientific Distinctions About Emotional Content • The 2-dimensional model of emotional content • It’s valenced (has a definite positive/negative, pleasant/unpleasant quality) • It’s physically arousing rather than calming • Data: Variations in valence and arousal affect memory performance differently (cf. Kensinger, 2004) • Variations in valence and arousal have different brain signatures • Valence = LVLPFC, MPFC, & RVLPFC activation • Arousal = L & R amygdale activation - Recent work has stressed that specific emotions (anger, sadness) may have unique semantic content [but that’s a story for another day]

4. Classic Ideas About How Emotion Affects Memory for Events • Dr. Johnson effect (“When a man knows he is to be hanged in a fortnight, it concentrates his mind wonderfully.”) • Scientific version: Negative content focuses attention on target events, improving verbatim memory and suppressing false memory • Go with the flow (e.g., Storbeck & Clore, 2005) • Positive content enhances meaning extraction, increasing false memory but leaving true memory unchanged • So, classic ideas add up to • Memory enhancement by negative emotion • Memory distortion by positive emotion • But, notice that these ideas are just about valence – arousal is missing in action

5. Fuzzy-Trace Theory & Emotion • Dual-trace theory of false memory • Verbatim traces of actual events: They support true memory and suppress false memory. • Gist traces of meaning content: They support false memories of meaning-sharing events and true memories. • FTT’s take on emotion • Valence is mainly a gist dimension, in 2 senses: Positive or negative valence is a concept in itself (“my junior prom was the pits”) but valence may also stimulate memory for other meaning content. [Think of it on analogy to semantic orienting tasks.] • Arousal is mainly a verbatim interference manipulation. (Sorry, Dr. Johnson.) Heating up the amygdale generates off-task noise that impairs verbatim memory for actual events. [Think of it on analogy to dual-task deficits.] • Negative valence stimulates semantic processing, relative to positive or neutral, producing stronger gist memories. • So, memory distortion is maximized by negative valence. • Caveats about the elderly and about children will be needed later.

6. How is Emotion-Induced Memory Distortion Studied in the Lab? • Separate emotion from study/test materials via mood induction before study; administer neutral study/test materials • Storbeck & Clore (2005); Bauml & Kuhbandner (2007); Corson & Verrier (2007) • Put the emotion in the study and test materials, as it is in crimes (e.g., Budson et al., 2006; Brainerd et al., in press) • Today’s experiments

7. Today’s Experiments • 2 experiments • 1 in Portuguese (Brazilian undergrads) • 1 in English (American undergrads) • Basic design: • Study several “emotional” DRM lists • Respond to conjoint recognition tests

8. Today’s Experiments • Emotional DRM lists • First 15 forward associates of a negative word (e.g., hungry, lie, thief), a neutral word (e.g., fruit, teacher, window), or a positive word (e.g., baby, god, hug) • Associates are presented as study words but the generating word is not • Generating words appear on memory tests as false memory probes • Arousal is controlled across the 3 valence types

9. Today’s Experiments • Conjoint recognition tests • Test probes: true (school), false (teacher), unrelated (lake – measures response bias) • Questions: verbatim = word on the list? gist = related to a word on the list? verbatim + gist = either a word on the list or a related word? • Math model: extracts measures of verbatim and gist memory, for both true and false items, from this 3 x 3 matrix

10. Combined Data (Signal Detection) of the Brazilian and U.S. Experiments

11. Combined Data of the Brazilian and U.S. Experiments

12. What the Data (d′) Show About Valence-Induced Memory Distortion • False memory is elevated by negative valence, relative to neutral valence. • False memory is lowered by positive valence, relative to neutral valence. • Net memory accuracy (d′ true - d′ false) is increased by positive, relative to neutral. • Net memory accuracy is decreased by negative, relative to neutral. • When valence is negative, memory is net inaccurate: The sign of d′ true - d′ false is negative.

13. Valence Effects on Verbatim and Gist Memory

14. Modeling Data: What Valence Does to Gist and Verbatim Memory • False memory probes: • Gist support for false items increases as we move from positive to neutral to negative. • Verbatim suppression of false items decreases as we move from positive to neutral to negative • True memory probes: • Gist support for true items increases from positive to neutral, but not from neutral to negative. • Verbatim support for true items varies only slightly across the 3 valence conditions

15. The Story So Far for Negative Valence • It increases false memory hugely and decreases net accuracy (because true memory does not increase nearly enough to compensate). • This is mainly a gist-memory effect. Negative valence is an especially good gist that is preferentially processed. • The distortion effects are valence-specific: Positive valence actually reduces false memory and increases net accuracy.

16. The Story So Far for Negative Valence • Arousal now needs to be folded into the valence picture • We’re working on it • CEL norming project • It looks like arousal amplifies gist processing (increasing false memory) when valence is positive

17. Two Caveats About Vulnerable Populations • Older adults, who are frequent victims of certain types of crimes: • Display positive gist-processing preferences, rather than the negative preferences of younger adults (Mikels, Carstensen). • So, it is likely that negative distortion effects will morph into positive ones in late adulthood. • Recent data from our labs and Mikel’s lab confirm this prediction. • Children, who are also frequent victims of certain types of crimes: • Display lower levels of false memory when distortion depends on extracting the gist of experience (Brainerd, Reyna, & Ceci, 2008). • So, it is likely that negative distortion effects will be absent or greatly attenuated in children and emerge with development. • Recent data from our labs confirm this prediction.