Tobias Sommer

Event segmentation divides continuous experience into discrete events. Previous research suggests that poorer temporal order memory and higher temporal distance ratings for pairs of items that were encoded across a boundary, compared to those encoded within the same event, serve as behavioural markers of event boundary perception. Four pre-registered experiments challenge the widely accepted interpretation that these effects depend solely on processes that occur during the encoding of event boundaries. We found that temporal order memory and temporal distance judgments depend critically on associative and reconstructive memory at retrieval, specifically memory for each item's event-defining source and for the order of those sources. Retrieval processes determined both the magnitude and direction of effects typically attributed solely to encoding processes. We outline a new retrieved-context model variant that distinguishes object- and event-based contextual evidence for temporal judgments. Our findings suggest that greater caution is required when interpreting behavioural markers of event segmentation.

Recent adversity (RA) increases the risk of later mental health problems, but the mechanisms underlying this association remain largely unclear. Altered associative learning and specifically threat learning processes may constitute a potential pathway. Cross-sectional studies link RA to reduced threat-safety discrimination, a process crucial for adaptive functioning; however, longitudinal evidence allowing for more causal conclusions is lacking. In this prospective longitudinal study, 69 healthy participants completed fear acquisition, 24h-delayed extinction training and a reinstatement-test at two measurement time points six months apart (T0 and T1). We captured exposure to RA between T0 and T1 as well as autonomic and neural responses (SCRs and BOLD-fMRI), fear ratings, and salivary and hair cortisol at both assessments. During acquisition training, at the beginning of extinction (i.e., fear recall) and reinstatement-test at T1, RA-exposed individuals showed less autonomic threat-safety discrimination than unexposed individuals, mainly driven by blunted threat signal responding. These group differences predicted depression levels at the 1 and 1.5 year follow-ups and were mirrored by distinct activation in key fear-related brain regions, including striatal regions, thalamus, vmPFC, insula, and amygdala, whereas self-reported fear was unrelated to RA. In conclusion, across multiple outcomes, RA shapes threat learning and retrieval under conditions of (potential) imminent threat, with reduced autonomic threat discrimination prospectively predicting elevated depressive symptoms at 1- and 1.5-year follow-up. Overall, these findings implicate altered threat learning and retrieval processes as a potential mechanistic pathway through which RA becomes biologically embedded, potentially elevating psychopathological risk.

Adverse childhood experiences (ACEs) are well established and strong risk factors for mental health challenges later in life, but the underlying mechanisms remain largely unclear. Associative learning, which shapes emotional and cognitive responses to environmental cues, may play a critical role in this relationship. However, the neural underpinnings linking ACEs and ACE load to alterations in associative threat and safety learning remain poorly understood. In this multimodal fMRI study, 171 participants (97 with ACEs, 74 without ACEs) underwent a one-day fear conditioning paradigm, which included fear acquisition, generalization, extinction, and a return of fear test (ROF) after reinstatement. During fear acquisition, generalization and the ROF test, higher ACE load was associated with reduced discrimination between threat and safety cues, primarily driven by blunted responses to the threat cue across arousal ratings and central nodes of the fear network key brain regions (striatal regions and the vmPFC). During fear generalization, individuals with ACEs showed reduced activation in key brain regions to the CS+ (and GS+) but no differences in generalization gradients. In contrast, ACEs were neither related to expectancy ratings for nor aversiveness ratings for the unconditioned aversive event. These findings indicate a striking dissociation between cognitive and affective threat processing - putatively originating from a reduced transfer of US-related arousal to the CS+ as a mechanistic pathway through which ACEs become physiologically and neurobiologically embedded, thereby increasing the risk for mental health challenges.

The Spielberger State-Trait Anxiety Inventory (STAI) is the most cited measure of state and trait anxiety, and is routinely employed in a variety of research and clinical contexts. Here, we investigate the temporal stability as well as the convergent and discriminant validity of the German version of the STAI trait scale (STAI-T) across multiple time points in two independent samples (105 and 120 Caucasians). We observed temporal stabilities of .42-.67 for intervals between 20 and 41 months and from .81-.87 for intervals of five to 12 months, with decreasing stability as the time interval increased. Temporal stability estimates of the STAI-T were similar to those of related constructs. Additionally, examining the relationships within a nomological network support the recent conclusion that the STAI-T also shares substantial variance with questionnaires measuring negative emotionality such as depression, and hence does not measure anxiety specifically - despite its name. These results provide further psychometric information on what the STAI-T actually measures and to what extent STAI-T scores are expected to be stable across longer time intervals. This is of relevance for researchers aiming, for example, to use the STAI-T scale for predicting symptom trajectories and evaluating the effectiveness of therapeutic interventions.

The Spielberger State-Trait Anxiety Inventory (STAI) is the most cited measure of state and trait anxiety, and is routinely employed in a variety of research and clinical contexts. Here, we investigate the temporal stability as well as the convergent and discriminant validity of the German version of the STAI-T scale across multiple time points in two independent samples (105 and 120 Caucasians). We observed temporal stabilities of .42 - .67 for intervals between 20 and 41 months and from .81 - .87 for intervals of five to 12 months, with decreasing stability as the time interval increased. Temporal stability estimates of the STAI-T were similar to those of related constructs. Additionally, examining the relationships within a nomological network support the recent conclusion that the STAI-T also shares substantial variance with questionnaires measuring negative emotionality such as depression, and hence does not measure anxiety specifically – despite its name. These results provide further psychometric information on what the STAI-T actually measures and to what extent STAI-T scores are expected to be stable across longer time intervals. This is of relevance for researchers aiming, for example, to use the STAI-T scale for predicting symptom trajectories and evaluating the effectiveness of therapeutic interventions.

Communication, often grounded in shared expectations, faces challenges when a Sender and Receiver lack a common linguistic background. Our study explores how people instinctively turn to the fundamental principles of the physical world to overcome such barriers. Specifically, through an experimental game in which Senders convey messages via trajectories, we investigate how they develop novel strategies without relying on common linguistic cues. We build a computational model based on the principle of expectancy violations and a set of common universal priors derived from movement kinetics. The model replicates participant-designed messages with high accuracy and shows how its core variable—surprise—predicts the Receiver’s physiological and neuronal responses in brain areas processing expectation violations. This work highlights the adaptability of human communication, showing how surprise can be a powerful tool in forming new communicative strategies without relying on common language.

Emotionally arousing events are typically vividly remembered, which is generally adaptive but may contribute to mental disorders such as post-traumatic stress disorder. Previous research on emotional memory focused primarily on events that were experienced only once, leaving the memory mechanisms underlying repeatedly encountered emotional events largely unexplored. Here, we aimed to elucidate the brain mechanisms associated with memory for recurring emotional events. Specifically, we sought to determine whether the memory enhancement for recurring emotional events is linked to more variable neural representations, as predicted by the encoding-variability hypothesis, or to more stable representations across repetitions, as suggested by a memory reinstatement account. To investigate this, we repeatedly presented healthy men and women with images of emotionally negative or neutral scenes during three consecutive runs in an MRI scanner. Subsequent free recall was, as expected, enhanced for emotional compared with neutral images. Neural data showed that this emotional enhancement of memory was linked to (1) activation of the amygdala and anterior hippocampus during the initial encounter of the emotional event and (2) increased neural pattern similarity in frontoparietal cortices across event repetitions. Most importantly, a multilevel-moderated mediation analysis revealed that the impact of neocortical pattern stability across repetitions on emotional memory enhancement was moderated by amygdala activity during the initial exposure to the emotional event. Together, our findings show that the amygdala response during the initial encounter of an emotional event boosts subsequent remembering through a more precise reinstatement of the event representation during subsequent encounters of the same event.

Rationale: Animal studies suggest that the so-called “female” hormone estrogen enhances spatial navigation and memory. This contradicts the observation that males generally out-perform females in spatial navigation and tasks involving spatial memory. A closer look at the vast number of studies actually reveals that performance differences are not so clear. Objectives: To help clarify the unclear performance differences between men and women and the role of estrogen, we attempted to isolate organizational from activational effects of estrogen on spatial navigation and memory. Methods: In a double-blind, placebo-controlled study, we tested the effects of orally administered estradiol valerate (E2V) in healthy, young women in their low-hormone menstrual cycle phase, compared to healthy, young men. Participants performed several first-person, environmentally rich, 3-D computer games inspired by spatial navigation and memory paradigms in animal research. Results: We found navigation behavior suggesting that sex effects dominated any E2 effects with men performing better with allocentric strategies and women with egocentric strategies. Increased E2 levels did not lead to general improvements in spatial ability in either sex but to behavioral changes reflecting navigation flexibility. Conclusion: Estrogen-driven differences in spatial cognition might be better characterized on a spectrum of navigation flexibility rather than by categorical performance measures or skills.