Drinking the waters of Lethe: Bringing voluntary choice into the study of voluntary forgetting.

The directed forgetting paradigm has long been used to test whether humans can voluntarily choose to forget learned information. However, to date, nearly all directed forgetting paradigms have involved a forced-choice paradigm, in which the participants are instructed about which learned information they should forget. While studies have repeatedly shown that this directed forgetting does lead to a decreased ability to later remember the information, it is still unclear whether these effects would be present if participants were allowed to, of their own accord, choose which information they wanted to forget. In two experiments here, we introduce a free-choice variety of the item method directed forgetting paradigm and show that directed forgetting effects are robust, both for instructed and voluntary forgetting. We discuss the implications of our findings for notions of voluntary forgetting and for the self-choice effect in memory.

Collective remembering and future forecasting during the COVID-19 pandemic: How the impact of COVID-19 affected the themes and phenomenology of global and national memories across 15 countries.

The COVID-19 pandemic created a unique set of circumstances in which to investigate collective memory and future simulations of events reported during the onset of a potentially historic event. Between early April and late June 2020, we asked over 4,000 individuals from 15 countries across four continents to report on remarkable (a) national and (b) global events that (i) had happened since the first cases of COVID-19 were reported, and (ii) they expected to happen in the future. Whereas themes of infections, lockdown, and politics dominated global and national past events in most countries, themes of economy, a second wave, and lockdown dominated future events. The themes and phenomenological characteristics of the events differed based on contextual group factors. First, across all conditions, the event themes differed to a small yet significant degree depending on the severity of the pandemic and stringency of governmental response at the national level. Second, participants reported national events as less negative and more vivid than global events, and group differences in emotional valence were largest for future events. This research demonstrates that even during the early stages of the pandemic, themes relating to its onset and course were shared across many countries, thus providing preliminary evidence for the emergence of collective memories of this event as it was occurring. Current findings provide a profile of past and future collective events from the early stages of the ongoing pandemic, and factors accounting for the consistencies and differences in event representations across 15 countries are discussed.

Odor associated memories are not necessarily highly emotional.

Laboratory and clinical studies have shown that odors tend to evoke highly emotional autobiographical memories that frequently come from an early period in life. One potential explanation for this effect is that all memories associated with odors are particularly emotional, while another potential explanation is that the presence of an (emotional) odor during retrieval leads to the participants' impression that the retrieved memory is particularly emotional. To this point, nearly all research on odor evoked autobiographical memories has relied on the presence of an odor to cue the memory, a procedure that does not allow one to distinguish whether the emotionality of the memories is due to the memory itself or the presence of the current cue. In contrast, in the current studies, no stimuli were presented during the retrieval of autobiographical memories. Instead, we asked people to report on memories specifically associated with the five traditional different senses or asked for information about autobiographical memories evoked throughout the day and assessed the role of the senses in those experienced memories. Across the three studies, using slightly different methodologies, we found that odor associated autobiographical memories are not more emotional or older than memories (mainly) associated with other modalities. Our results carefully put into question the notion that odor associated autobiographical memories are more emotional than autobiographical memories mostly associated with other modalities. Since the difference between the presented and previous studies lies in a different situation at AM retrieval, these results present evidence towards retrieval-based explanations.

Emotional oddball: A review on memory effects.

How do emotional stimuli influence perception, attention, and ultimately memory? This debate at the cross-section of emotion and cognition research has a long tradition. The emotional oddball paradigm (EOP) has frequently been applied to investigate the detection and processing of (emotional) change detection (Schlüter & Bermeitinger, 2017). However, the EOP has also been used to reveal the effects of emotional deviants on memory for serially presented stimuli. In this integrative article, we review the results of 29 experiments published between the years 2000 and 2017. Based on these data, we provide an overview of how the EOP is applied in the context of memory research. We also review and integrate the empirical evidence for memory effects in the EOP (with a special focus on retrograde and anterograde emotion-induced effects) and present theories of emotional memory as well as their fit with the results obtained by the EOP. Directions for future research are presented that would help to address important issues of the current debate around emotion-induced memory effects.

An in-depth review of the methods, findings, and theories associated with odor-evoked autobiographical memory.

Over the past nearly 35 years, there has been sporadic interest in what has commonly come to be known as the Proust phenomenon, whereby autobiographical memories are retrieved and experienced differently when evoked by odors as compared with other types of cues, such as words, images or sounds. The purpose of this review is threefold. First, we provide a detailed analysis of the methods used to investigate Proust effects. Second, we review and analyze the various findings from the literature and determine what we feel to be the most important and stable findings. Third, we provide a series of previously postulated and new hypotheses that attempt to account for the various findings. Given the early stage of research, the current review aims to provide a measure of organization to the field, as well serve as a guide for how future investigations may address the topic. We conclude with the recommendation that research in this area shift its focus from establishing the phenomenon towards explaining its causes.

Olfactory Context Dependent Memory: Direct Presentation of Odorants.

Information is retrieved more effectively when the retrieval occurs in the same context as that in which the information was first encoded. This is termed context dependent memory (CDM). One category of cues that have been shown to effectively produce CDM effects are odors. However, it is unclear what the boundary conditions of these CDM effects are. In particular, given that olfaction has been called an implicit sense, it is possible that odors are only effective mnemonic cues when they are presented in the background. This assertion seems even more likely given that previous research has shown odors to be poor cues during paired associate memory tests, where odors are in the focus of attention as mnemonic cues for other information. In order to determine whether odors are only effective contextual mnemonic cues when presented outside the central focus of an observer, an olfactory CDM experiment was performed in which odorants were presented directly, rather than ambiently. Direct presentation was accomplished with the aid of an olfactometer. The olfactometer not only allows for direct presentation of odorants, but provides other methodological benefits, including the allowance of trial by trial manipulations of odorant presentations and, relatedly, time-specific releases of odorants. The presence of the same odor during both encoding and retrieval enhanced memory performance, regardless of whether the odor was presented ambiently or directly. This finding can serve as a basis for future olfactory CDM research which can utilize the benefits of direct presentation.

Response priming with motion primes: negative compatibility or congruency effects, even in free-choice trials.

How actions are chosen, and what they are influenced by, has been the focus of several research traditions. Influences on actions are often studied using compatibility paradigms, such as response priming. Here, a first stimulus (i.e., the prime) is presented shortly before a second stimulus (i.e., the target) which has to be classified. Reaction times to the target are often reduced when primes and targets are compatible compared to incompatible primes and targets-i.e., a positive compatibility effect (PCE). There are, however, some conditions in which reliably negative compatibility effects (NCEs), with faster reactions to incompatible targets, are found. Actions in real life are often influenced by perceived motion and are less determined by following (target) stimuli as it is the case in typical response priming studies with predetermined stimulus-response mappings. Thus, in the current experiment we used motion primes in forced-choice trials (with >> and << as targets) as well as in free-choice trials (with <> and >< as targets). Essentially, we found PCEs in the short-SOA condition and NCEs in the long-SOA condition. The pattern was not qualified by task (i.e., forced choice/free choice). The results provide evidence that NCEs with motion primes are found even without strong links between target stimuli and responses and that especially PCEs can be found with simpler and smaller targets than have been used in previous experiments.

Olfactory Context-Dependent Memory and the Effects of Affective Congruency.

Odors have been claimed to be particularly effective mnemonic cues, possibly because of the strong links between olfaction and emotion processing. Indeed, past research has shown that odors can bias processing towards affectively congruent material. In order to determine whether this processing bias translates to memory, we conducted 2 olfactory-enhanced-context memory experiments where we manipulated affective congruency between the olfactory context and to-be-remembered material. Given the presumed importance of valence to olfactory perception, we hypothesized that memory would be best for affectively congruent material in the olfactory enhanced context groups. Across the 2 experiments, groups which encoded and retrieved material in the presence of an odorant exhibited better memory performance than groups that did not have the added olfactory context during encoding and retrieval. While context-enhanced memory was exhibited in the presence of both pleasant and unpleasant odors, there was no indication that memory was dependent on affective congruency between the olfactory context and the to-be-remembered material. While the results provide further support for the notion that odors can act as powerful contextual mnemonic cues, they call into question the notion that affective congruency between context and focal material is important for later memory performance.

On the use (and misuse?) of the Edinburgh Handedness Inventory.

Researchers who study human cognition and behavior, especially from a neuroscience perspective, often measure subjects' handedness. The most common measure of handedness is the Edinburgh Handedness Inventory (EHI; Oldfield, 1971). Several potential problems with the EHI have been identified during its long history. We informally observed that individual researchers have adopted a variety of modified versions of the EHI, each addressing perceived shortcomings in its own way. To confirm this, we reviewed 899 articles reporting usage of the EHI from 1998 to 2012. For those articles reporting details of the instrument used, we coded information about test items, response format, and scheme for classifying individuals as right-handed. We found tremendous diversity in all three components of the inventory, confirming that many variants of the EHI are used in contemporary research. We furthermore report evidence that researchers who use variants may be unaware that they are not using the original instrument. Variant usage appears to be largely ad hoc and lacking any semblance of uniformity within the scientific community. We discuss how highly variable usage of the EHI may imperil efforts to produce replicable and convergent research findings, and we offer recommendations for future action.

Consistency of handedness, regardless of direction, predicts baseline memory accuracy and potential for memory enhancement.

Research has shown that consistently right-handed individuals have poorer memory than do inconsistently right- or left-handed individuals under baseline conditions but more reliably exhibit enhanced memory retrieval after making a series of saccadic eye movements. From this it could be that consistent versus inconsistent handedness, regardless of left/right direction, is an important individual difference factor in memory. Or, more specifically, it could be the presence or absence of consistent right-handedness that matters for memory. To resolve this ambiguity, we compared consistent and inconsistent left- and right-handers on associative recognition tests taken after saccades or a no-saccades control activity. Consistent-handers exhibited poorer memory than did inconsistent-handers following the control activity, and saccades enhanced retrieval for consistent-handers only. Saccades impaired retrieval for inconsistent-handers. None of these effects depended on left/right direction. Hence, this study establishes handedness consistency, regardless of direction, as an important individual difference factor in memory.