Cognitive control and suppression of memories of an emotional film

Prospective associations between intelligence, working memory capacity, and intrusive memories of a traumatic film: Potential mediating effects of rumination and memory disorganization

BACKGROUND AND OBJECTIVES

Field research indicates that lower intelligence may predispose trauma-exposed individuals towards the development of re-experiencing symptoms. However, this assumption requires further testing in controlled prospective studies. In the current analog study, we tested whether lower fluid intelligence and lower working memory capacity (WMC) independently contribute to intrusion development. Moreover, we investigated potential mediating effects of trauma memory characteristics and trait rumination.

METHODS

118 healthy participants completed tests measuring fluid intelligence and WMC. Two days later, they were exposed to a film clip depicting traumatic events (i.e., so-called trauma film). After exposure to the film, intrusions were assessed using a diary and an intrusion triggering task.

RESULTS

Our analyses revealed a negative correlation between fluid intelligence and intrusions during the intrusion triggering task. WMC did not correlate with any intrusion measure. Moreover, planned analyses did not yield any mediation effects.

LIMITATIONS

We used the trauma film paradigm to examine analog posttraumatic stress symptoms. This approach limits the generalizability of our findings with regard to symptom development following real-life traumatic events.

CONCLUSIONS

Our results show for the first time that higher fluid intelligence is associated with fewer intrusions of a trauma film. This association was evident for laboratory but not for ambulatory intrusions. By demonstrating this association using a prospective experimental design, our study importantly corroborates previous field research.

Negative item memory and associative memory: Influences of working memory capacity, anxiety sensitivity, and looming cognition

BACKGROUND AND OBJECTIVES

Traumatic or negative stimuli facilitate item memory but impair associated context memory. Vulnerability factors related to the maintenance and onset of posttraumatic stress disorder (PTSD), such as anxiety sensitivity, looming cognitive style, dissociation, and low working memory capacity, have been identified. However, little is known about how these factors influence negative item or associative memory.

METHODS

Eighty-five undergraduates completed self-report questionnaires, the operation span with words (OSPAN) task, and an item and associative memory task in which incidental encoding of negative and neutral items and context information (Day 1) was followed by an unexpected retrieval test (Day 2).

RESULTS

The results showed greater Hit rates and False Alarms on item memory and lower accuracy on context memory with negative stimuli than with neutral stimuli, replicating previous findings. Low working memory capacity and high dissociation were correlated with low negative item memory. Under low working memory capacity, high levels of anxiety sensitivity and looming cognitive style predicted high dissociation levels and low accuracy for negative item memory. There were no individual differences involving associative memory.

LIMITATIONS

A nonclinical sample was used, which limits the generalizability of our results to clinical samples.

CONCLUSIONS

Dissociation could be a coping strategy for reducing negative item memory. Anxiety sensitivity and looming cognitive style facilitate dissociative coping; however, working memory capacity buffers against these vulnerabilities.

A multiverse analysis of early attempts to replicate memory suppression with the Think/No-think Task

In 2001, Anderson and Green [2001. Suppressing unwanted memories by executive control. Nature, 410(6826), 366-369] showed memory suppression using a novel Think/No-think (TNT) task. When participants attempted to prevent studied words from entering awareness, they reported fewer of those words than baseline words in subsequent cued recall (i.e., suppression effect). The TNT literature contains predominantly positive findings and few null-results. Therefore we report unpublished replications conducted in the 2000s (N = 49; N = 36). As the features of the data obtained with the TNT task call for a variety of plausible solutions, we report parallel "universes" of data-analyses (i.e., multiverse analysis) testing the suppression effect. Two published studies (Wessel et al., 2005. Dissociation and memory suppression: A comparison of high and low dissociative individuals' performance on the Think-No think Task. Personality and Individual Differences, 39(8), 1461-1470, N = 68; Wessel et al., 2010. Cognitive control and suppression of memories of an emotional film. Journal of Behavior Therapy and Experimental Psychiatry, 41(2), 83-89. https://doi.org/10.1016/j.jbtep.2009.10.005, N = 80) were reanalysed in a similar fashion. For recall probed with studied cues (Same Probes, SP), some tests (sample 3) or all (samples 2 and 4) showed statistically significant suppression effects, whereas in sample 1, only one test showed significance. Recall probed with novel cues (Independent Probes, IP) predominantly rendered non-significant results. The absence of statistically significant IP suppression effects raises problems for inhibition theory and its implication that repression is a viable mechanism of forgetting. The pre-registration, materials, data, and code are publicly available (https://osf.io/qgcy5/).

Arresting visuospatial stimulation is insufficient to disrupt analogue traumatic intrusions

Intrusive memories are a core symptom of Post-Traumatic Stress Disorder (PTSD). A growing body of analogue studies using trauma films suggest that carrying out specific demanding tasks (e.g., playing the video game Tetris, pattern tapping) after the analogue trauma can reduce intrusive memories. To examine the mechanism behind this effect, we tested whether mere engagement with attention-grabbing and interesting visual stimuli disrupts intrusive memories, and whether this depends on working memory resources and/or the concurrent activation of trauma film memories. In a total sample of 234 healthy participants, we compared no-task control conditions to a perceptual rating task with visually arresting video clips (i.e., non-emotional, complex, moving displays), to a less arresting task with non-moving, blurred pictures (Study 1), and to more demanding imagery tasks with and without repetitive reminders of the trauma film (Study 2). Generally, we found moderate to strong evidence that none of the conditions lead to differences in intrusion frequency. Moreover, our data suggest that intrusive memories were neither related to individual differences in working memory capacity (i.e., operation span performance; Study 1), nor to the degree of engagement with a visuospatial task (i.e., one-week recognition performance; Study 2). Taken together, our findings suggest that the boundary conditions for successful interference with traumatic intrusions may be more complex and subtle than assumed. Future studies may want to test the role of prediction errors during (re-)consolidation, deliberate efforts to suppress thoughts, or the compatibility of the task demands with the individual's skills.

Investigating the effect of proactive interference control training on intrusive memories

Intrusive re-experiencing is a hallmark symptom of Posttraumatic Stress Disorder (PTSD). According to prominent models of intrusive phenomena, intrusive memories may result from impairments in the efficiency of working memory capacity (WMC), more specifically proactive interference control. Yet, experimental research is scarce. Therefore, the present study aimed to investigate experimentally the role of proactive interference control in intrusive memories. We randomly assigned 57 healthy participants to either receive a high interference control training or a low interference control training. Participants were then exposed to highly distressing film clips. WMC was assessed before and after the training. Intrusion symptoms were assessed directly post-training and after one week using an Intrusion Provocation Task (IPT), a one-week intrusions diary, and the retrospective intrusion subscale of the Impact of Event Sale - Revised (IES-R). Results indicated that both groups reported improvements in WMC and fewer intrusions on the second IPT post-training, with no differences between groups. Similarly, no group differences on intrusions were found at one-week follow-up (i.e., intrusion diary and IES-R). To conclude, these data are not consistent with the hypothesis that WMC plays a role in intrusive re-experiencing. Implications for future research are discussed.

A prospective examination of risk factors in the development of intrusions following a trauma analog

Several factors have been linked to the severity of posttraumatic distress, although retrospective designs in much of the literature limit conclusions regarding the temporal relation between risk factors and corresponding symptoms. To address these concerns, the current project employed an analog trauma paradigm to assess the impact of background characteristics, stress response, and post-stressor affect regulation on subjective distress and intrusive memories experienced during the subsequent processing of emotional stimuli. University students (N = 184; 56% female, 42% White/Non-Hispanic) were shown graphic scenes of a televised suicide. Physiological activation was recorded during exposure with emotion ratings collected following the film. Participants then viewed a sadness- or humor-eliciting prime under instructions to inhibit or naturally express emotion. Intrusions experienced during the priming film and residual distress at study's conclusion were rated prior to debriefing. Hierarchical regression identified reductions in emotional valence as a robust predictor of intrusions and distress. Sympathetic activation and exposure to the sadness prime were associated with intrusion frequency, whereas attenuated parasympathetic response predicted intrusion intensity. Expressive inhibition demonstrated a unique association with residual distress. Results suggest peritraumatic processes and post-exposure factors may hold more prominent relations with immediate trauma-related distress as compared to pre-existing survivor characteristics.

Memory consolidation reconfigures neural pathways involved in the suppression of emotional memories

The ability to suppress unwanted emotional memories is crucial for human mental health. Through consolidation over time, emotional memories often become resistant to change. However, how consolidation impacts the effectiveness of emotional memory suppression is still unknown. Using event-related fMRI while concurrently recording skin conductance, we investigated the neurobiological processes underlying the suppression of aversive memories before and after overnight consolidation. Here we report that consolidated aversive memories retain their emotional reactivity and become more resistant to suppression. Suppression of consolidated memories involves higher prefrontal engagement, and less concomitant hippocampal and amygdala disengagement. In parallel, we show a shift away from hippocampal-dependent representational patterns to distributed neocortical representational patterns in the suppression of aversive memories after consolidation. These findings demonstrate rapid changes in emotional memory organization with overnight consolidation, and suggest possible neurobiological bases underlying the resistance to suppression of emotional memories in affective disorders.

As memories consolidate over time, they become resistant to change, though how this impacts the volitional suppression of memories is not known. Liu and colleagues show that, after overnight consolidation, aversive memories exhibit distributed prefrontal representations and are harder to suppress.

Cognitive Load Undermines Thought Suppression in Acute Stress Disorder

Thought suppression studies demonstrate that attempts to suppress can be undermined by cognitive load. We report the first instance in which this has been tested experimentally in a sample of recently traumatized individuals. Individuals with and without acute stress disorder (ASD) were recruited following recent trauma and randomized to load or no load conditions (N=56). They monitored intrusive memories during baseline, suppression, and think anything phases. The impact of suppression and load on self-reported intrusions, attention bias (dot-probe), and memory priming (word-stem task) was assessed. The ASD load group were less able to suppress memories (d=0.32, CI95 [-0.15, 0.83], p=.088) than the ASD no load group (d=0.63, CI95 [0.08, 1.24], p<.001). In the think anything phase, the ASD load group reported more intrusions than the ASD no load or non-ASD groups (with and without load). No consistent findings were observed in relation to attentional bias. ASD load individuals exhibited stronger priming responses for motor vehicle accident and assault words than all other groups (ds between 0.35-0.73). Working memory did not moderate any outcomes of interest. The findings indicate that cognitive load interferes with suppression and may enhance access to trauma memories and associated material. The study extends previous research by demonstrating these effects for the first time in a clinical sample of recent survivors of trauma.

Individual differences in resting heart rate variability and cognitive control in posttraumatic stress disorder

Post-traumatic stress disorder (PTSD) is characterized by deficits in cognitive functioning, particularly cognitive control. Moreover, these deficits are thought to play a critical role in the etiology and maintenance of core PTSD symptoms such as intrusive thoughts and memories. However, the psychophysiological concomitants of cognitive control remain largely unexamined. In this article, we suggest that individual differences in heart rate variability (HRV), a physiological index of self-regulatory capacity, may underlie the association between cognitive control ability and intrusive cognitions in PTSD. We review evidence showing that individual differences in HRV at rest are related to prefrontal cortical activity and performance on a broad range of cognitive control tasks. We highlight the importance of inhibition as a mechanism by which HRV promotes successful cognitive control. In addition, we summarize recent research linking individual differences in HRV to performance on laboratory tasks that assess the ability to control unwanted memories and intrusive thoughts. We conclude by suggesting that future studies should examine the role of low HRV as a risk factor for developing PTSD.

Low emotional response to traumatic footage is associated with an absence of analogue flashbacks: an individual participant data meta-analysis of 16 trauma film paradigm experiments

Most people will experience or witness a traumatic event. A common occurrence after trauma is the experience of involuntary emotional memories of the traumatic event, herewith “flashbacks”. Some individuals, however, report no flashbacks. Prospective work investigating psychological factors associated with an absence of flashbacks is lacking. We performed an individual participant data meta-analysis on 16 experiments (n = 458) using the trauma film paradigm to investigate the association of emotional response to traumatic film footage and commonly collected baseline characteristics (trait anxiety, current depression, trauma history) with an absence of analogue flashbacks. An absence of analogue flashbacks was associated with low emotional response to the traumatic film footage and, to a lesser extent, low trait anxiety and low current depression levels. Trauma history and recognition memory for the film were not significantly associated with an absence of analogue flashbacks. Understanding why some individuals report an absence of flashbacks may aid preventative treatments against flashback development.

Vividness of general mental imagery is associated with the occurrence of intrusive memories

BACKGROUND AND OBJECTIVES

Intrusive memories of traumatic events constitute a core feature of post-traumatic stress disorder. However, the association of pre-traumatic factors with post-traumatic intrusive memories is still only poorly understood. The current study investigated the extent to which vividness of general mental imagery prior to an analogue stressor is positively associated with occurrence of intrusive images following such a stressor.

METHODS

Sixty-seven participants were exposed to video material depicting the aftermath of serious road traffic accidents. Additionally, participants filled in questionnaires on mental imagery, affect, peri-traumatic processing style, and intrusive memories.

RESULTS

Vividness of mental imagery before the analogue stressor correlated positively with the amount, vividness, and emotional distress due to intrusive images shortly after the analogue stressor and on the subsequently five days. Importantly, mental imagery assessed pre-stressor was associated with intrusive memories independently of trait anxiety and depression as well as participants' emotional response to the video. Peri-traumatic data-driven processing was also related to intrusive memories but not to the vividness of pre-stressor mental imagery.

LIMITATIONS

An analogue design was used. Results need to be replicated in a prospective design with survivors of traumatic events according to DSM-IV criteria.

CONCLUSIONS

The findings indicate that high levels of vividness of general mental imagery may contribute to the development of intrusive imaginal memories following exposure to traumatic events.

Towards a cognitive and neurobiological model of motivated forgetting

Historically, research on forgetting has been dominated by the assumption that forgetting is passive, reflecting decay, interference, and changes in context. This emphasis arises from the pervasive assumption that forgetting is a negative outcome. Here, we present a functional view of forgetting in which the fate of experience in memory is determined as much by motivational forces that dictate the focus of attention as it is by passive factors. A central tool of motivated forgetting is retrieval suppression, a process whereby people shut down episodic retrieval to control awareness. We review behavioral, neurobiological, and clinical research and show that retrieval suppression leads us to forget suppressed experiences. We discuss key questions necessary to address to develop this model, relationships to other forgetting phenomena, and the implications of this research for understanding recovered memories. This work provides a foundation for understanding how motivational forces influence what we remember of life experience.