Memory modulation in the classroom: selective enhancement of college examination performance by arousal induced after lecture

Laboratory studies examining moderate physiological or emotional arousal induced after learning indicate that it enhances memory consolidation. Yet, no studies have yet examined this effect in an applied context. As such, arousal was induced after a college lecture and its selective effects were examined on later exam performance. Participants were divided into two groups who either watched a neutral video clip (n=66) or an arousing video clip (n=70) after lecture in a psychology course. The final examination occurred two weeks after the experimental manipulation. Only performance on the group of final exam items that covered material from the manipulated lecture were significantly different between groups. Other metrics, such as the midterm examination and the total final examination score, did not differ between groups. The results indicate that post-lecture arousal selectively increased the later retrieval of lecture material, despite the availability of the material for study before and after the manipulation. The results reinforce the role of post-learning arousal on memory consolidation processes, expanding the literature to include a real-world learning context.     

Choose Your Words Wisely: What Verbal Hesitation Indicates About Eyewitness Accuracy

Researchers have demonstrated qualitative differences in witness verbal reports made in the presence and absence of misinformation. The present study examined changes in linguistic markers present in verbal reports in the context of a repeated‐retrieval misinformation study. After witnessing an event, an immediate retrieval group engaged in a free‐recall test associated with the event. The delayed retrieval group completed a filler task. Following, all participants were presented with a post‐event narrative that included neutral, consistent, and misleading details. Both groups then took two free‐recall tests. We found that hesitations were more likely to accompany correctly remembered details if those details were altered in the narrative, than if there was consistency between the original event and narrative. We also found that retrieval prior to misinformation positively influenced the inclusion of hesitations in free‐recall reports that immediately followed the narrative.Copyright © 2015 John Wiley & Sons, Ltd.     

Trauma and memory: effects of post-event misinformation, retrieval order, and retention interval

The present study concerned effects of misinformation, retrieval order, and retention interval on eyewitness memory for a traumatic event (a vivid murder). Relations between misinformation acceptance and compliance were also examined. The classic three-stage misinformation paradigm (Loftus, 1979) was employed, with a multi-component recognition test added. Either immediately or 2 weeks after viewing a distressing film, 232 adults read a narrative (misleading or control) about the murder and then took a recognition test that tapped memory for central and peripheral details. Test-item order either matched the chronology of the film or was randomly determined. Significant misinformation effects were obtained. Moreover, control participants were more accurate in response to questions about central than peripheral information; however, this was not so for misinformed participants. Sequential but not random retrieval order resulted in a higher proportion of correct responses for central as opposed to peripheral misinformation questions. Compliance was significantly related to misinformation effects. Delay increased participants' suggestibility, impaired memory accuracy, and produced higher confidence ratings for misinformed participants compared to controls. Findings indicate that even for a highly negative event, adults' memory is not immune to inaccuracies and suggestive influences.     

Paradoxical effects of testing: retrieval enhances both accurate recall and suggestibility in eyewitnesses

Although retrieval practice typically enhances memory retention, it can also impair subsequent eyewitness memory accuracy (Chan, Thomas, & Bulevich, 2009). Specifically, participants who had taken an initial test about a witnessed event were more likely than nontested participants to recall subsequently encountered misinformation—an effect we called retrieval-enhanced suggestibility (RES). Here, we sought to test the generality of RES and to further elucidate its underlying mechanisms. To that end, we tested a dual mechanism account, which suggests that RES occurs because initial testing (a) enhances learning of the later misinformation by reducing proactive interference and (b) causes the reactivated memory trace to be more susceptible to later interference (i.e., a reconsolidation account). Three major findings emerged. First, RES was found after a 1-week delay, where a robust testing benefit occurred for event details that were not contradicted by later misinformation. Second, blockage of reconsolidation was unnecessary for RES to occur. Third, initial testing enhanced learning of the misinformation even when proactive interference played a minimal role.     

Post-encoding emotional arousal enhances consolidation of item memory,but not reality-monitoring source memory

The current study examined whether the effect of post-encoding emotional arousal on item memory extends to reality-monitoring source memory and, if so, whether the effect depends on emotionality of learning stimuli and testing format. In Experiment 1, participants encoded neutral words and imagined or viewed their corresponding object pictures. Then they watched a neutral, positive, or negative video. The 24-hour delayed test showed that emotional arousal had little effect on both item memory and reality-monitoring source memory. Experiment 2 was similar except that participants encoded neutral, positive, and negative words and imagined or viewed their corresponding object pictures. The results showed that positive and negative emotional arousal induced after encoding enhanced consolidation of item memory, but not reality-monitoring source memory, regardless of emotionality of learning stimuli. Experiment 3, identical to Experiment 2 except that participants were tested only on source memory for all the encoded items, still showed that post-encoding emotional arousal had little effect on consolidation of reality-monitoring source memory. Taken together, regardless of emotionality of learning stimuli and regardless of testing format of source memory (conjunction test vs. independent test), the facilitatory effect of post-encoding emotional arousal on item memory does not generalize to reality-monitoring source memory.     

Repeated testing in eyewitness memory: a means to improve recall of a negative emotional event

Participants viewed either a violent, arousing film or a non-violent, control version of the same film. After viewing the film, they made three successive attempts to recall details of the event. Participants who were exposed to the negative emotional event were better than control participants at recalling details of the event itself, but they were worse at recalling details that preceded or followed the violence. Both groups of participants recalled significantly more information over successive recall attempts, suggesting that memory impairment due to arousal can be alleviated by repeated testing. Repeated testing was also associated with a small but reliable increase in memory intrusions. The implications of these findings for research on hypermnesia and on the relationship between arousal and memory are discussed. © 1998 John Wiley & Sons, Ltd.     

Testing potentiates new learning in the misinformation paradigm

Retrieval enhanced suggestibility (RES) is the finding that the misinformation effect is exacerbated when a test precedes misleading postevent information (Chan, Thomas, & Bulevich Psychological Science 20: 66–73, 2009). In the present study, we tested three hypotheses relevant to RES. First, we examined whether retrieval of critical details was necessary for the RES effect. Second, we examined whether initial testing influenced the allocation of attention to critical details during postevent information processing. Finally, we examined whether RES resulted in impaired access to the originally learned information. We compared three groups of participants in three experiments: an identical-test group, a related-test group, and a standard misinformation group. Both testing groups were tested on the original event before the introduction of misinformation; however, the identical-test group took the same test before and after the misinformation, whereas the related-test group took different tests before and after misinformation. We found that testing before misleading postevent information affected attention allocation to details in the postevent narrative. Furthermore, the RES effect did not accompany reduced accessibility to the original information, as measured by a modified–modified free recall test. These data have implications for how testing may potentiate new learning.     

Memory enhancement by a semantically unrelated emotional arousal source induced after learning

It has been well established that moderate physiological or emotional arousal modulates memory. However, there is some controversy about whether the source of arousal must be semantically related to the information to be remembered. To test this idea, 35 healthy young adult participants learned a list of common nouns and afterward viewed a semantically unrelated, neutral or emotionally arousing videotape. The tape was shown after learning to prevent arousal effects on encoding or attention, instead influencing memory consolidation. Heart rate increase was significantly greater in the arousal group, and negative affect was significantly less reported in the non-arousal group after the video. The arousal group remembered significantly more words than the non-arousal group at both 30 min and 24 h delays, despite comparable group memory performance prior to the arousal manipulation. These results demonstrate that emotional arousal, even from an unrelated source, is capable of modulating memory consolidation. Potential reasons for contradictory findings in some previous studies, such as the timing of "delayed" memory tests, are discussed.     

Misleading Suggestions can Alter Later Memory Reports even Following a Cognitive Interview

Taking an immediate recall test prior to misinformation exposure can increase eyewitness suggestibility—a finding termed retrieval‐enhanced suggestibility. Here, we examined whether retrieval‐enhanced suggestibility would occur when participants were administered an immediate Cognitive Interview (CI). The CI is an investigative interviewing technique that consistently elicits more correct details in memory reports than standard interviews. In this study, participants watched a video of a crime and then completed a distractor task (control condition), a free recall test, or the CI. They then heard misinformation presented in a narrative. Participants produced more accurate memory details in the CI than in free recall despite spending equal time on both tasks. However, the CI also increased the later report of misinformation relative to the control condition. These results show that initial retrieval can increase subsequent suggestibility even when such retrieval occurs under relatively ideal conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Post-event spontaneous intrusive recollections and strength of memory for emotional events in men and women

Spontaneous intrusive recollections (SIRs) follow traumatic events in clinical and non-clinical populations. To determine whether any relationship exists between SIRs and enhanced memory for emotional events, participants viewed emotional or neutral films, had their memory for the films tested two days later, and estimated the number of SIRs they experienced for each film. SIR frequency related positively to memory strength, an effect more pronounced in the emotional condition. These findings represent the first demonstration of a relationship between SIRs occurring after an emotional experience and subsequent memory strength for that experience. The results are consistent with the possibility that emotional arousal leads both to elevated SIR frequency and better memory, and that the covert rehearsal associated with SIRs enhances memory for emotional relative to neutral stimuli. Additional evidence of menstrual cycle influences on SIR incidence in female participants appears to merit consideration in future work.     

The effect of mood on confidence in false memories

The goal of this study was to examine the effect of mood on suggestibility in the misinformation paradigm. To investigate the relative effects of valence and arousal, as well as affect-specific influences, six mood conditions were included: positive mood with low/high arousal (serene/happy), negative mood with low/high arousal (sad/angry), neutral mood, and a control condition. Participants watched a movie and were exposed to misleading information by means of a narrative. Memory was tested in a surprise forced-choice recognition task, with confidence judgements. The mood induction procedure was shown to be effective. A significant misinformation effect confirmed that participants were misled by the false information provided. Mood did not affect susceptibility to the misinformation effect, but did significantly influence participants’ belief in their false memories. Feeling sad induced the highest confidence ratings. Results are discussed in terms of different problem-solving strategies associated with discrete affective states, and have implications for both legal and clinical settings.     

Why misinformation is more likely to be recognised over time: A source monitoring account

Although memory for actual events tends to be forgotten over time, memory for misinformation tends to be retrieved at a stable rate over long delays or at a rate greater than that found immediately after encoding. To examine whether source monitoring errors contribute to this phenomenon, two experiments investigated subjects' memory for the source of misinformation at different retention intervals. Subjects viewed a slide presentation, read a narrative containing misinformation, and, either 10 minutes or 1 week later, completed a recognition test about details seen in the slides and about the source of these details. After the longer retention interval in both experiments, participants were more likely to agree that they had seen misleading information and were also more likely to incorrectly associate the misinformation with the slide event. Theoretical implications of these findings are considered.     

Cortisol response and psychological distress predict susceptibility to false memories for a trauma film

For eyewitness testimony to be considered reliable, it is important to ensure memory remains accurate following the event. As many testimonies involve traumatic, as opposed to neutral, events, it is important to consider the role of distress in susceptibility to false memories. The aim of this study was to investigate whether cortisol response following a stressor would be associated with susceptibility to false memories. Psychological distress responses were also investigated, specifically, dissociation, intrusions, and avoidance. Participants were allocated to one of three conditions: those who viewed a neutral film (N?=?35), those who viewed a real trauma film (N?=?35), and a trauma “reappraisal” group where participants were told the film was not real (N?=?35). All received misinformation about the film in the form of a narrative. Participants provided saliva samples (to assess cortisol) and completed distress and memory questionnaires. Cortisol response was a significant predictor of the misinformation effect. Dissociation and avoidance were related to confabulations. In conclusion, following a stressor an individual may differ with regard to their psychological response to the event, and also whether they experience a cortisol increase. This may affect whether they are more distressed later on, and also whether they remember the event accurately.     

Moderate-to-vigorous intensity cycling exercise immediately after visual learning enhances delayed recognition memory performance

A single bout of acute aerobic exercise has been shown to improve long-term memory, though it is unclear if exercise before learning or after learning is optimal for memory enhancement. Although some research has demonstrated that exercise before learning is ideal, investigations have consistently shown that acute arousal post-learning is a powerful memory enhancer. Therefore, the purpose of this investigation was to compare the effects of self-perceived hard cycling before or after learning on recognition memory for emotional and neutral images, and examine the relationship between central noradrenergic activity and memory performance. Seventy-two males and females (18–35 years of age) participated in this between-subjects study. Participants were randomly assigned to one of the following groups: exercise before learning, exercise after learning, and control. Participants in the exercise groups engaged in 20 min of cycling at a rating of perceived exertion (RPE) of 15 (“hard”) on the Borg RPE scale before or after viewing a series of 90 pleasant, unpleasant, and neutral images (30 each). Participants in the control group engaged in no exercise before or after image viewing. At several time points throughout the experiment, saliva was collected to measure salivary alpha amylase (sAA), a marker of central noradrenergic activity. One-week later, recognition memory was assessed where participants viewed 180 images (90 new) and had to identify which images were previously viewed. Participants in the exercise after learning group had significantly higher recognition memory compared to the control group, but this was not seen with exercise before learning. sAA was not correlated with memory in any group, though it did increase during exercise. These results demonstrate that acute self-perceived hard cycling post-learning, but not pre-learning, improves recognition memory, though this was unrelated to the exercise-induced increase in central noradrenergic activity as measured in saliva.     

Do emotional stimuli enhance or impede recall relative to neutral stimuli? An investigation of two “false memory” tasks

Many eyewitness memory situations involve negative and distressing events; however, many studies investigating “false memory” phenomena use neutral stimuli only. The aim of the present study was to determine how both the Deese–Roediger–McDermott (DRM) procedure and the Misinformation Effect Paradigm tasks were related to each other using distressing and neutral stimuli. Participants completed the DRM (with negative and neutral word lists) and viewed a distressing or neutral film. Misinformation for the film was introduced and memory was assessed. Film accuracy and misinformation susceptibility were found to be greater for those who viewed the distressing film relative to the neutral film. Accuracy responses on both tasks were related, however, susceptibility to the DRM illusion and Misinformation Effect were not. The misinformation findings support the Paradoxical Negative Emotion (PNE) hypothesis that negative stimuli will lead to remembering more accurate details but also greater likelihood of memory distortion. However, the PNE hypothesis was not supported for the DRM results. The findings also suggest that the DRM and Misinformation tasks are not equivalent and may have differences in underlying mechanisms. Future research should focus on more ecologically valid methods of assessing false memory.     

Misled subjects may know more than their performance implies

Many studies have demonstrated that subjects exposed to misleading postevent information are likely to report the misinformation with confidence on subsequent tests of memory for the event. The purpose of the present studies was to determine whether subjects exposed to misleading postevent information come to believe they remember seeing the misinformation at the original event. A second question addressed by the present studies is whether exposure to misinformation reduces subjects' ability to remember the source of items they witnessed at the original event. In two experiments, subjects viewed a slide sequence depicting an event, were subsequently exposed to misleading information or neutral information about selected aspects of the event, and were later tested on their memory for the source of original and misleading details. The results showed that exposure to misinformation did not lead subjects to believe they remembered seeing the misinformation, nor did it reduce subjects' ability to accurately identify the source of originally seen details. The same pattern of results was obtained whether subjects were tested immediately (Experiment 1) or after a 1-day delay (Experiment 2). Collectively, the results suggest that subjects may report misinformation even if they know they do not remember seeing it.     

Recalling a Witnessed Event Increases Eyewitness Suggestibility: The Reversed Testing Effect

ABSTRACT— People's later memory of an event can be altered by exposure to misinformation about that event. The typical misinformation paradigm, however, does not include a recall test prior to the introduction of misinformation, contrary to what real-life eyewitnesses encounter when they report to a 911 operator or crime-scene officer. Because retrieval is a powerful memory enhancer (the testing effect), recalling a witnessed event prior to receiving misinformation about it should reduce eyewitness suggestibility. We show, however, that immediate cued recall actually exacerbates the later misinformation effect for both younger and older adults. The reversed testing effect we observed was based on two mechanisms: First, immediate cued recall enhanced learning of the misinformation; second, the initially recalled details became particularly susceptible to interference from later misinformation, a finding suggesting that even human episodic memory may undergo a reconsolidation process. These results show that real-life eyewitness memory may be even more susceptible to misinformation than is currently envisioned.     

Overcoming Misinformation Effects in Eyewitness Memory: Effects of Encoding Time and Event Cues

Eyewitness memory is often distorted when misleading information is presented to subjects after encoding. Three experiments explored ways to overcome these misinformation effects. In Experiment 1, subjects viewed slides of a robbery, at a rate of four or seven seconds per slide. Five minutes later subjects were given a recognition test with few (1–3) or numerous (6–13) event cues. Providing numerous retrieval cues improved overall performance, but did not reduce the effects of misinformation. W ith week-long delays (Experiment 2) numerous retrieval cues did eliminate misinformation effects, but only when subjects viewed slides at the slower rate (seven seconds per slide). Experiment 3 essentially replicated this pattern, using a modified test to eliminate any biasing effects of distractors. Given adequate encoding and numerous retrieval cues, misinformation effects were eliminated, suggesting that under some conditions misinformation makes event memory inaccessible, but not unavailable.     

积极情绪加速心血管反应恢复的自主神经活动机制

通过对不同情绪唤醒状态下的心率变异性（HRV）和呼吸性窦性心率不齐（RSA）分析,探讨了积极情绪加速高唤醒消极情绪引起的心血管反应向基线恢复的自主神经活动机制。实验表明：与在观看高唤醒恐惧影片结束后观看悲伤影片和中性视频比较,观看高唤醒恐惧影片结束后观看快乐影片加速了高唤醒恐惧影片引起的心率、指脉等心血管反应向基线的恢复;与在观看高唤醒恐惧影片结束后观看悲伤视频和中性视频材料比较,观看高唤醒恐惧影片结束观看快乐影片后的恢复期,被试的迷走神经激活水平迅速增强,迷走神经激活水平甚至超过基线期。因此,积极情绪加速高唤醒消极情绪刺激引起的心血管反应向基线恢复,其自主神经活动机制是在积极情绪状态下个体有更强的迷走神经激活。     

Is saccade-induced retrieval enhancement a potential means of improving eyewitness evidence?

Saccade-induced retrieval enhancement (SIRE) is the effect whereby making bilateral saccades enhances the subsequent retrieval of memories. Two experiments explored SIRE's potential to improve eyewitness evidence. Participants viewed slideshows depicting crimes, and received contradictory and additive misinformation about event details either once (Experiment 1) or three times (Experiment 2). Participants then performed saccades or a fixation control task before being tested on their memory for the slideshows and making confidence judgements. Saccades increased discrimination between seen and unseen event details regardless of whether or what type of misinformation was presented. Because prior studies indicated that SIRE might be more robust for individuals who are strongly right-handed versus not, we examined SIRE as a function of handedness and found that saccades improved memory for event details regardless of participants' handedness. However, participants who were not strongly right-handed had fewer false memories than participants who were strongly right-handed, extending previous findings of superior memory among individuals who are not strongly right-handed. Saccades also increased confidence in true memories (Experiment 1) and decreased confidence in false memories (Experiment 2). The results support SIRE's potential to improve eyewitness evidence.