Department of Cognitive Sciences

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Shared memories of event details are crucial to eyewitness testimony. When different people encode or recall the same event, similar scene-specific neural activity patterns emerge across individual brains. However, it remains unclear whether these patterns are specific to event details and how test expectancy (i.e., expecting free recall or general memory tests) and misinformation affect them. In this study, 100 participants were randomly assigned to view one of two versions of each event. Both versions featured identical scenarios, but with different details. About half of the participants were informed about the upcoming free recall before viewing events, while the others were told to expect a general memory test. Functional magnetic resonance imaging was used to record their brain activity during four stages: viewing original events, initial free recall, reading misinformation, and final free recall of original events. The neuroimaging data were analyzed based on the similarity of neural patterns across participants. Test expectancy increased the similarity of detail-specific neural activity patterns between individuals when they viewed original events in brain regions relevant for visual attention. Misinformation increased the likelihood of people forming shared false memories of event details. People who formed shared false memories exhibited similar detail-specific patterns of activity in the dorsomedial prefrontal cortex when reading misinformation. People who formed shared true memories exhibited similar detail-specific patterns of activity in the inferior parietal lobe when viewing original events, as well as in the ventrolateral prefrontal cortex and middle temporal gyrus when recalling them after exposure to misinformation. Our findings revealed that different brain regions of the default mode network play distinct roles in the encoding and recall of event details shared by individuals.

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Hippocampal subfields differentially develop and age, and they vary in vulnerability to neurodegenerative diseases. Innovation in high-resolution imaging has accelerated clinical research on human hippocampal subfields, but substantial differences in segmentation protocols impede comparisons of results across laboratories. The Hippocampal Subfields Group (HSG) is an international organization seeking to address this issue by developing a histologically valid, reliable, and freely available segmentation protocol for high-resolution T₂-weighted 3 T MRI (http://www.hippocampalsubfields.com). Here, we report the first portion of the protocol focused on subfields in the hippocampal body; protocols for the head and tail are in development. The body protocol includes definitions of the internal boundaries between subiculum, Cornu Ammonis (CA) 1-3 subfields, and dentate gyrus, in addition to the external boundaries of the hippocampus apart from surrounding white matter and cerebrospinal fluid. The segmentation protocol is based on a novel histological reference dataset labeled by multiple expert neuroanatomists. With broad participation of the research community, we voted on the segmentation protocol via an online survey, which included detailed protocol information, feasibility testing, demonstration videos, example segmentations, and labeled histology. All boundary definitions were rated as having high clarity and reached consensus agreement by Delphi procedure. The harmonized body protocol yielded high inter- and intra-rater reliability. In the present paper we report the procedures to develop and test the protocol, as well as the detailed procedures for manual segmentation using the harmonized protocol. The harmonized protocol will significantly facilitate cross-study comparisons and provide increased insight into the structure and function of hippocampal subfields across the lifespan and in neurodegenerative diseases.

Eileen Kowler was a member of the team of cognitive scientists that was assembled over a half a century ago by Robert M. Steinman. This team had grown and spanned several institutions in this country, as well as in Europe. The mechanisms governing the movements of the eyes were always at the center of Eileens attention, but her research, as well as the research of our interdisciplinary group, is best understood by realizing its roots in Gestalt psychology. In the first part, this paper describes perspectives of two of the authors from the point of view of Eileen Kowlers collaborators. The second part provides a new look at the origins of Gestalt psychology, pointing out the scientific context of what has been referred to as the Gestalt revolution. The Gestalt revolution closely followed similar revolutions in mathematics and in physics, and it gave rise to new questions and challenges that have received recognition only recently.

Conspiratorial thinking is an indelible part of American politics; indeed, conspiracy theories proliferated in North America even before the founding of the United States. A current headwind of trends appears to facilitate a surge in conspiratorial thinking, including the increased spread and accessibility of misinformation, steady declines in public trust in authority figures, and an increasingly polarized electorate marked by mutual partisan animosity. The annual symposium of the UC Irvine Center for Neuropolitics brought together experts in law, political science, neuroscience, philosophy, and psychology to discuss why and how conspiracy thought develops and persists. This paper synthesizes the insights from that symposium, addressing the foundations of conspiracy thinking in both individuals and society as a whole, and its place in the current American political landscape. Through integrating various disciplinary perspectives, the symposium aimed to identify possible pathways to alleviating the prevalence and influence of conspiratorial thinking.

The Greenland shark (Somniosus microcephalus) is the longest-living vertebrate and inhabits the exceptionally dim and cold waters of the Arctic deep sea. Due to its extreme lifespan, harsh environmental conditions, and prevalent corneal parasitisation, the Greenland shark has previously been thought to have impaired or degenerated vision. Here, we present genomic, transcriptomic, histological and functional evidence that the Greenland shark retains an intact visual system well-adapted for life in dim light. Histology and in vitro opsin expression revealed visual adaptations typical of deep-sea species, including densely packed, elongated rods and a short-wavelength shift in rod visual pigment sensitivity compared to shallow-water sharks. In situ hybridisation confirmed the presence of essential visual cell types: rods, Müller glia, and bipolar, amacrine, and ganglion cells. Moreover, despite being over a century old, the examined specimens showed no obvious signs of retinal degeneration. Using whole genome and retinal RNA-sequencing, we further show that dim-light (rod-based) vision genes are intact and robustly expressed, while many bright-light (cone-based) vision genes have become pseudogenized and/or are no longer expressed. Finally, we identify robust expression of DNA repair-associated genes in the retina, which may help support long-term maintenance of retinal integrity over the Greenland shark’s extreme lifespan.

Episodic memory involves remembering the what, when, and where components of an event. It has been observed in humans, other vertebrates, and the invertebrate cuttlefish. In clever behavioral experiments, cuttlefish have been shown to have episodic-like memory, where they demonstrate the ability to remember when and where a preferred food source will appear. The present work replicates this behavior with a parsimonious model of episodic memory. To further test this model and explore episodic-like memory, we introduce a predator-prey scenario in which the agent must remember what creatures (e.g. predator, desirable prey, or less desirable prey) appear at a given time and region of the model environment. This simulates similar situations that cuttlefish face in the wild. They will typically hide when predators are in the area, and hunt for prey when available. When the memory model is queried for an action (e.g., hunt or hide), the cuttlefish agent hunts for preferred food, like shrimp, when available, and hides at other times when a predator appears. When the memory model is queried for a place, the cuttlefish agent acts opportunistically, seeking less-preferred food (e.g., crabs) if it is located farther from a predator. These differences show how behavior can be altered depending on how memory is accessed. Querying the model over time might mimic mental time travel, a hallmark of episodic memory. Although developed with cuttlefish in mind, the model shares similarities with the hippocampal indexing theory and captures aspects of vertebrate episodic memory. This suggests that the underlying mechanisms supporting episodic-like behavior in the present model may be an example of convergent cognitive evolution.

The EZ-diffusion model is a simplification of the popular drift diffusion model of choice response times that allows researchers to calculate diffusion model parameters directly from data with no need for expensive computations. The EZ-diffusion model is based on a system of equations in which the diffusion model’s drift rate, boundary separation, and nondecision time parameters are jointly used to predict three summary statistics (the accuracy rate and the mean and variance of the correct response times). These equations can then be inverted to obtain estimators for the three parameters from these summary statistics. Here, we describe a probabilistic formulation of the EZ-diffusion model that can serve as a hyper-efficient proxy model to the drift diffusion model. The new formulation is based on sampling distributions of summary statistics and consists only of normal and binomial distributions. It can easily be implemented in any probabilistic programming language. We demonstrate the validity of the proxy model through extensive simulation studies and provide multiple examples (via https://osf.io/bzkpn/), including an implementation in JASP. We conclude that, although the recovery of some parameters with the proxy model is biased, the recovery of regression parameters is good, making the method useful for cognitive psychometrics (i.e., explanatory cognitive modeling). Casting the EZ-diffusion model in the broad family of Bayesian generative models allows us to benefit from mature implementations, practical workflows, and powerful extensions that are not possible without a probabilistic implementation and not feasible with the regular drift diffusion model. Code and example applications are provided via https://osf.io/bzkpn/.