What can directed forgetting tell us about clinical populations?

Memory updating and the structure of event representations

People form memories of specific events and use those memories to make predictions about similar new experiences. Living in a dynamic environment presents a challenge: How does one represent valid prior events in memory while encoding new experiences when things change? There is evidence for two seemingly contradictory classes of mechanism: One differentiates outdated event features by making them less similar or less accessible than updated event features. The other integrates updated features of new events with outdated memories, and the relationship between them, into a structured representation. Integrative encoding may occur when changed events trigger inaccurate predictions based on remembered prior events. We propose that this promotes subsequent recollection of events and their order, enabling adaptation to environmental changes.

Memory modulation: Dominance of negative visual context over neutral verbal memory

Neutral memories can be modulated via intentional memory control paradigms such as directed forgetting. In addition, previous studies have shown that neutral visual memories can be modulated indirectly, via remember and forget instructions towards competing verbal memories. Here we show that direct modulation of neutral verbal memory strength is impaired by negative visual context, and that negative visual context is resistant to indirect memory modulation. Participants were directly instructed to intentionally remember or forget newly encoded neutral verbal information. Importantly, this verbal information was interleaved with embedded negative visual context. Results showed that negative visual context eliminated the well-documented effect of direct instructions to intentionally remember verbal content. Furthermore, negative visual memory was highly persistent, overcoming its sensitivity to indirect modulation shown in previous studies. Finally, these memory effects persisted to the following day. These results demonstrate the dominance of negative visual context over neutral content, highlighting the challenges associated with memory modulation in psychopathologies involving maladaptive processing of negative visual memories.

Effects of anxiety level on directed forgetting of emotional information and related metacognitive judgments

The present study investigated intentional forgetting of emotional information in low vs. high anxiety groups, by using a directed forgetting paradigm. The groups were formed based on their scores on measures of state and trait anxiety. Participants were provided with positive, negative, and neutral photographs with either remember or forget instructions and further provided metacognitive judgments of learning for each photograph, indicating how likely they are to recognize the photograph in a subsequent recognition test. In the recognition test, they identified the photographs that they had seen in the learning session, irrespective of instruction. The results showed that directed forgetting was only observed in the high anxiety group. Furthermore, higher anxiety scores negatively correlated with the recognition of negative to-be-forgotten information, indicating that high anxiety is associated with a better ability to forget negative information. Metacognitive judgments showed awareness of the forget instructions and the valence of the photographs, but they were not affected by anxiety level. The results suggest that the effects of anxiety on cognitive control may be different between participants with higher vs. lower anxiety levels in a non-clinical sample. The results are discussed within several theoretical frameworks which claim that anxiety may lead to the inhibition and avoidance of negatively valenced mental content.

The effect of chronic academic stress on intentional forgetting

This study investigated whether chronic academic stress could affect the directed forgetting (DF) process. Both the stress group (undergoing preparation for a major academic examination) and the control group performed a DF task. A forgetting cue was presented after a to-be-forgotten (TBF) word, whereas no cue appeared after a to-be-remembered (TBR) item in the study phase. An old/new recognition test was used in the test phase. The results showed that (1) the stress group showed a higher level of self-reported stress, state anxiety, negative affect, and decreased cortisol awakening response (CAR) compared with the control group, suggesting a higher level of stress for the stress group. (2) Both groups showed superior recognition performance of TBR than TBF items, suggesting a DF effect. (3) The stress group showed inferior recognition performance of TBF items and an enhanced DF effect compared with the control group. These results demonstrated that the intentional memory control process might be enhanced under chronic academic stress.

Survival processing and directed forgetting: enhanced memory for both to-be-remembered and to-be-forgotten information

In a recently published study, (Parker, A., Parkin, A., & Dagnall, N. (2021). Effects of survival processing on list method directed forgetting. Memory (Hove, England), 29(5), 645-661) examined directed forgetting in a survival processing context using the list-method directed forgetting procedure. (Parker, A., Parkin, A., & Dagnall, N. (2021). Effects of survival processing on list method directed forgetting. Memory (Hove, England), 29(5), 645-661) found that the costs of directed forgetting were greater when engaging in survival processing than when making moving relevance or pleasantness ratings. However, according to most current accounts of directed forgetting, engaging in survival processing should not have enhanced the directed forgetting effect but rather should not have impacted the directed forgetting effect. In the present study, we further investigated how survival processing impacts directed forgetting using both the list (Experiment 1) and item method of directed forgetting (Experiment 2). In Experiment 1, we did not replicate the findings of (Parker, A., Parkin, A., & Dagnall, N. (2021). Effects of survival processing on list method directed forgetting. Memory (Hove, England), 29(5), 645-661) - that the directed forgetting effect is enhanced when engaging in survival processing. Rather, we demonstrated that making survival ratings and moving ratings yielded a similar cost of directed forgetting for List 1 items. In Experiment 2, survival processing provided an overall memory benefit (but not when recalling to-be-remembered and to-be-forgotten items in separate recall tests) but did not differentially impact to-be-remembered and to-be-forgotten words. Thus, we did not find evidence that survival processing influences directed forgetting.

Depersonalization Disorder: Directed Forgetting as a Function of Emotionality

There exists some evidence for a link between dissociation and emotionally avoidant information processing, yet studies to date have been contradictory. Our goal was to investigate emotionally avoidant processing in Depersonalization Disorder (DDD) using a directed forgetting (DF) paradigm. Thirty-two participants with DSM-IV DDD and 40 healthy controls performed an item-method DF task using positive, negative, and neutral words. Participants were also administered the Dissociative Experiences Scale (DES) and the Childhood Trauma Questionnaire (CTQ). The DDD group demonstrated significantly lower directed forgetting for negative, but not positive or neutral, words compared to controls. In the combined sample, DES total, depersonalization/derealization, and amnesia scores significantly inversely predicted explicit cued recall for to-be-forgotten negative words (higher dissociation, lower forgetting), while the CTQ was not predictive. The findings do not support emotionally avoidant processing in this paradigm; rather, DDD may be characterized by a diminished capacity to actively control attention and direct it away from emotionally disturbing material when instructed to do so.

Directed forgetting of pictures of everyday objects

Directed forgetting is a laboratory task in which subjects are explicitly cued to forget certain items and remember others. Volitional control over the contents of memory has been used to study clinical disorders, with successful intentional control of memory being a hallmark of a healthy mind. Yet the degree of volitional forgetting over the content of visual long-term memory is unclear when compared to words. Different kinds of visual stimuli (e.g., abstract symbols, line drawings, scenes) may not equally be susceptible to voluntary control in memory, and intentional forgetting studies have shown both twice as much forgetting of pictures compared to words (think/no-think task) and half as much forgetting of pictures compared to words (directed forgetting task). In the present study, we systematically test volitional control over pictures of everyday objects using item-method directed forgetting procedures. We find that subjects are able to intentionally prioritize memory for pictures cued as to be remembered over pictures cued to be forgotten. Here we show that directed forgetting effects are observed using pictures of everyday objects (albeit to a weaker extent compared to directed forgetting of words), suggesting increased confidence for generalization of directed forgetting literature to real-world applications. However, we caution clinical applications of intentional memory control until the underlying direction causing this effect (upregulation of remember-cued items or downregulation of forget-cued items) is known.

If you don't let it in, you don't have to get it out: Thought preemption as a method to control unwanted thoughts

To attain goals, people must proactively prevent interferences and react to interferences once they occur. Whereas most research focuses on how people deal with external interferences, here we investigate the use of proactive and reactive control in dealing with unwanted thoughts. To examine this question, we asked people to generate an association to each of several repeating cue words, while forbidding the repetition of associations. Reactively rejecting and replacing unwanted repeated associations after they occur entails slower response times. Conversely, proactive control entails constricting the search space and thus faster response times. To gain further insight into different potential proactive thought control mechanisms, we augmented the analysis of raw response times with a novel, hypothesis-based, tractable computational model describing how people serially sample associations. Our results indicate that people primarily react to unwanted thoughts after they occur. Yet, we found evidence for two latent proactive control mechanisms: one that allows people to mitigate the episodic strengthening of repeated thoughts, and another that helps avoid looping in a repetitive thought. Exploratory analysis showed a relationship between model parameters and self-reported individual differences in the control over unwanted thoughts in daily life. The findings indicate the novel task and model can advance our understanding of how people can and cannot control their thoughts and memories, and benefit future research on the mechanisms responsible for unwanted thought in different psychiatric conditions. Finally, we discuss implications concerning the involvement of associative thinking and various control processes in semantic fluency, decision-making and creativity.

Item method directed forgetting occurs independently of borderline personality traits, even for borderline-salient items

Clinical populations sometimes demonstrate difficulties forgetting stimuli related to their trauma-related disorder, perhaps because their intense personal connection to these stimuli produce deficits in the inhibitory control abilities necessary for forgetting. The present work examined this possibility for people who have high levels of traits implicated in borderline personality disorder (BPD). In two well-powered studies, we found no evidence for deficits in forgetting specific to BPD traits, even for people with clinically significant levels of the traits, contrary to previous studies. The present experiments updated the designs from earlier experiments to employ the most contemporary methods to examine directed forgetting recommended by recent reviews. With these improved methods, Study 1 found that participants showed significant directed forgetting for BPD-related words independent of their level of BPD traits, perhaps because the BPD-related words were so strongly associated with one another. Study 2 found that when we removed the strong relatedness between the stimuli, forgetting of BPD-relevant words was significant and did not interact with BPD symptomology. We concluded that in contrast to people with PTSD who show specific inhibitory deficits for trauma-related works, people with BPD show normal, intact inhibitory control even for words that they should find threatening.