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Target Selection And Enhancement During Attentional Tracking, Marvin R. Maechler

Dartmouth College Ph.D Dissertations

At any waking moment, we are bombarded with more sensory information than we can fully process. Attention is necessary to deal with the dynamic world we live in. One fundamental function of vision and attention is to keep track of moving objects, but what are the targets of attention during tracking?

One of the first theories of attentional tracking predicted that targets would be selected at early processing stages. By employing the double-drift illusion, which dissociates physical and perceived positions of moving objects, we investigated which of these positions is selected for tracking. Contrary to earlier theories and in line …

(Meta-)Physical Artworks: Digital Augmentation In Art Observation, Macy A. Toppan

Dartmouth College Master’s Theses

Augmented art— the subgenre of art that incorporates physical and digital artwork— is a rapidly growing field driven by advancing technology and a new generation for whom that tech is a given. Yet the presence of media like augmented and virtual reality in exhibition remains a controversial subject. Rather than focusing on the many theoretical debates about whether digital pieces can qualify as "good" art, we study it in practice through the eyes of the casual art observer. This paper highlights the audience in a within-participant study that asked viewers to take in a physical sculpture intentionally built with virtual …

Left Inferior Frontal Gyrus Connectivity With The Dorsomedial Subsystem Of Default Network Tracks Real-World Conversation Behaviour, Dhaval M. Bhatt

Dartmouth College Master’s Theses

Social interactions are multifaceted, complex, and critical to social behaviour as they help gather information, develop social connections, and regulate social behaviour (Lakey & Orehek, 2011; Testard et al., 2021; Jolly & Chang, 2021). Among social interactions, conversations find a special place for humans due to the nuances associated with language, conversational behaviour (e.g., gestures), and context (e.g., where conversations occur and what is discussed). Researchers have studied aspects of single conversation behaviour, content related to conversations, and brain function (Sievers et al., 2020). However, little is known about the brain function of densely-sampled in-person conversation behaviour. Filling this gap …

Say That Again: The Role Of Multimodal Redundancy In Communication And Context, Brandon Javier Dormes

Cognitive Science Senior Theses

With several modes of expression, such as facial expressions, body language, and speech working together to convey meaning, social communication is rich in redundancy. While typically relegated to signal preservation, this study investigates the role of cross-modal redundancies in establishing performance context, focusing on unaided, solo performances. Drawing on information theory, I operationalize redundancy as predictability and use an array of machine learning models to featurize speakers' facial expressions, body poses, movement speeds, acoustic features, and spoken language from 24 TEDTalks and 16 episodes of Comedy Central Stand-Up Presents. This analysis demonstrates that it is possible to distinguish between these …

Utilizing Mixed Graphical Network Models To Explore Parent Psychological Symptoms And Their Centrality To Parent Mental Health In Households With High Child Screen Usage, Piper F. Stacey, Nicholas C. Jacobson, Damien Lekkas

Computer Science Senior Theses

Especially among adolescents, screens are being used more than ever. In conjunction with this trend, mental illness is increasingly prevalent among both adults and children, and parental psychological problems are shown to be associated with children's TV watching, video watching, and gaming (Pulkki-Råback et al., 2022). This study aims to approach parent mental illness symptom by symptom to explore which specific symptoms are most central to parent psychological problems in households where children show high screen time behaviors. We draw from the Adolescent Brain Cognitive Development Study (ABCD Study®), a nationwide sample of 11,875 children aged 10-13 collected by …

Towards Scalable Mental Health: Leveraging Digital Tools In Combination With Computational Modeling To Aid In Treatment And Assessment Of Major Depressive Disorder, Matthew D. Nemesure

Dartmouth College Ph.D Dissertations

Major depressive disorder (MDD) is a debilitating disorder that impacts the lives of nearly 280 million individuals worldwide, representing 5% of the overall adult population. Unfortunately, these statistics have been both trending upward and are also likely an underestimate. This can be primarily attributed to lack of screening paired with a lack of providers. Worldwide, there are roughly 450 individuals living with MDD per mental health care provider. Adding to this burden, approximately half of affected individuals that do receive care of any kind will fail to remain in remission. The goal of this thesis work is to leverage statistical …

Mapping The Malleable Self: How Self-Views Are Represented And Learned Within The Social Brain, Sasha Carmela Brietzke

Dartmouth College Ph.D Dissertations

Humans possess a unique and wide-ranging ability to self-reflect that takes center stage in our everyday cognition. While many people believe their own self to be immutable, different contexts may warp how we perceive the self. The goal of this dissertation is to investigate two lenses through which we may view the self: (1) across time in the past and future, and (2) through the eyes of others via evaluative feedback. In Studies 1-3, I demonstrate that people’s ratings of their own personality become increasingly less differentiated as they consider more distant past and future selves. This effect was preferential …

What Makes Conversation Good? How Responsivity, Topics, And Insider Language Predict Feelings Of Connection, Emma M. Templeton

Dartmouth College Ph.D Dissertations

We spend our lives having conversations, and some inevitably go better than others. What happens in conversation that makes people feel connected? To explore this question, I recorded pairs of strangers and friends having unstructured conversations. In Chapter 1, I show that people who feel connected tend to respond quickly, creating short gaps between turns. However, long gaps are not necessarily bad. Although long gaps signal moments of disconnection and awkwardness for strangers, they mark moments of heightened connection for friends by providing space for enjoyment and mutual reflection. In Chapter 2, I examine how people start their conversations. Specifically, …

How Do We Represent Possibilities In The Visual World? — An Analysis Of Amodal Completion Under Cognitive And Perceptual Load., Camden Parker

Dartmouth College Undergraduate Theses

How do cognitive and perceptual load affect the way we experience the world when the visual scene is incomplete or partially occluded? The present study seeks to answer this question with a series of experiments based on primed matching, amodal completion, and load theory. In Experiment 1, we replicated results that amodal completion is automatic and supports multiple possible completions. In Experiment 2, we found that working memory load decreases the priming effects of both partially occluded and fully visible shapes. In Experiment 3, we found that perceptual load decreases the priming effect of partially occluded shapes more so than …

Analyzing Behavioral Adaptation To Covid-19 And Return To Pre-Pandemic Baselines In A Cohort Of College Seniors, Vlado Vojdanovski

Computer Science Senior Theses

As the critical phase of the COVID-19 pandemic seems to be winding down, it is important to analyze the adjustment to COVID-19 and return to normalcy of various populations. In this study we focus on the behavioral adjustments exhibited by a cohort of N=114 college seniors. To infer COVID-19 adjustment we compare the 2021 year (second year of COVID-19) to the 2020 year (first year of COVID-19) and 2019 (prepandemic baseline year). We begin with a broad analysis between the second and first covid year, finding that the second year of COVID-19 shows significant returns to pre-pandemic baselines on multiple …

Identifying Optimal Course Structures Using Topic Models, Tehut Tesfaye Biru

Dartmouth College Undergraduate Theses

This research project investigates whether there exists an optimal way to structure topics in educational course content that results in higher levels of engagement among students. It is implemented by fitting topic models to transcripts of educational videos contained in the Khan Academy platform. The fitted models were used to extract topic trajectories across time for each video and subsequently clustered based on whether they have similar “shapes”. The differences in mean engagement metrics per cluster suggest that some course shapes are more palatable to students regardless of subject matter. Additionally, the topic trajectories suggest a constant progression of topics …

Detecting Receptivity For Mhealth Interventions In The Natural Environment, Varun Mishra, Florian Künzler, Jan-Niklas Kramer, Elgar Fleisch, Tobias Kowatsch, David Kotz

Dartmouth Scholarship

Just-In-Time Adaptive Intervention (JITAI) is an emerging technique with great potential to support health behavior by providing the right type and amount of support at the right time. A crucial aspect of JITAIs is properly timing the delivery of interventions, to ensure that a user is receptive and ready to process and use the support provided. Some prior works have explored the association of context and some user-specific traits on receptivity, and have built post-study machine-learning models to detect receptivity. For effective intervention delivery, however, a JITAI system needs to make in-the-moment decisions about a user's receptivity. To this end, …

When Do Drivers Interact With In-Vehicle Well-Being Interventions? An Exploratory Analysis Of A Longitudinal Study On Public Roads, Kevin Koch, Varun Mishra, Shu Liu, Thomas Berger, Elgar Fleisch, David Kotz, Felix Wortmann

Dartmouth Scholarship

Recent developments of novel in-vehicle interventions show the potential to transform the otherwise routine and mundane task of commuting into opportunities to improve the drivers' health and well-being. Prior research has explored the effectiveness of various in-vehicle interventions and has identified moments in which drivers could be interruptible to interventions. All the previous studies, however, were conducted in either simulated or constrained real-world driving scenarios on a pre-determined route. In this paper, we take a step forward and evaluate when drivers interact with in-vehicle interventions in unconstrained free-living conditions.

To this end, we conducted a two-month longitudinal study with 10 …

A Comparison Of Neural Decoding Methods And Population Coding Across Thalamo-Cortical Head Direction Cells, Zishen Xu, Wei Wu, Shawn S. Winter, Max L. Mehlman, William N. Butler, Christine M. Simmons, Ryan E. Harvey, Laura E. Berkowitz, Yang Chen, Jeffrey S. Taube, Aaron A. Wilber, Benjamin J. Clark

Dartmouth Scholarship

Head direction (HD) cells, which fire action potentials whenever an animal points its head in a particular direction, are thought to subserve the animal’s sense of spatial orientation. HD cells are found prominently in several thalamo-cortical regions including anterior thalamic nuclei, postsubiculum, medial entorhinal cortex, parasubiculum, and the parietal cortex. While a number of methods in neural decoding have been developed to assess the dynamics of spatial signals within thalamo-cortical regions, studies conducting a quantitative comparison of machine learning and statistical model-based decoding methods on HD cell activity are currently lacking. Here, we compare statistical model-based and machine learning approaches …

Metaanalysis Of The Relationship Between Violent Video Game Play And Physical Aggression Over Time, Anna T. Prescott, James Sargent, Jay G. Hull

Dartmouth Scholarship

To clarify and quantify the influence of video game violence (VGV) on aggressive behavior, we conducted a metaanalysis of all prospective studies to date that assessed the relation between exposure to VGV and subsequent overt physical aggression. The search strategy identified 24 studies with over 17,000 participants and time lags ranging from 3 months to 4 years. The samples comprised various nationalities and ethnicities with mean ages from 9 to 19 years. For each study we obtained the standardized regression coefficient for the prospective effect of VGV on subsequent aggression, controlling for baseline aggression. VGV was related to aggression using …

Social Saliency Of The Cue Slows Attention Shifts, Vassiki Chauhan, Matteo Visconti Di Oleggio Castello, Alireza Soltani, Maria I. Gobbini

Dartmouth Scholarship

Eye gaze is a powerful cue that indicates where another person's attention is directed in the environment. Seeing another person's eye gaze shift spontaneously and reflexively elicits a shift of one's own attention to the same region in space. Here, we investigated whether reallocation of attention in the direction of eye gaze is modulated by personal familiarity with faces. On the one hand, the eye gaze of a close friend should be more effective in redirecting our attention as compared to the eye gaze of a stranger. On the other hand, the social relevance of a familiar face might itself …

Optimizing Virtual Reality For All Users Through Gaze-Contingent And Adaptive Focus Displays, Nitish Padmanaban, Robert Konrad, Tal Stramer, Emily Cooper, Gordon Wetzstein

Dartmouth Scholarship

From the desktop to the laptop to the mobile device, personal computing platforms evolve over time. Moving forward, wearable computing is widely expected to be integral to consumer electronics and beyond. The primary interface between a wearable computer and a user is often a near-eye display. However, current generation near-eye displays suffer from multiple limitations: they are unable to provide fully natural visual cues and comfortable viewing experiences for all users. At their core, many of the issues with near-eye displays are caused by limitations in conventional optics. Current displays cannot reproduce the changes in focus that accompany natural vision, …

A Computational Psychiatry Approach Identifies How Alpha-2a Noradrenergic Agonist Guanfacine Affects Feature-Based Reinforcement Learning In The Macaque, S. A. Hassani, M. Oemisch, M. Balcarras, S. Westendorff, S Ardid, M. A. Van Der Meer, P. Tiesinga, T. Womelsdorf

Dartmouth Scholarship

Noradrenaline is believed to support cognitive flexibility through the alpha 2A noradrenergic receptor (a2A-NAR) acting in prefrontal cortex. Enhanced flexibility has been inferred from improved working memory with the a2A-NA agonist Guanfacine. But it has been unclear whether Guanfacine improves specific attention and learning mechanisms beyond working memory, and whether the drug effects can be formalized computationally to allow single subject predictions. We tested and confirmed these suggestions in a case study with a healthy nonhuman primate performing a feature-based reversal learning task evaluating performance using Bayesian and Reinforcement learning models. In an initial dose-testing phase we found a Guanfacine …

Variations In Crowding, Saccadic Precision, And Spatial Localization Reveal The Shared Topology Of Spatial Vision, John A. Greenwood, Martin Szinte, Bilge Sayim, Patrick Cavanagh

Dartmouth Scholarship

Visual sensitivity varies across the visual field in several characteristic ways. For example, sensitivity declines sharply in peripheral (vs. foveal) vision and is typically worse in the upper (vs. lower) visual field. These variations can affect processes ranging from acuity and crowding (the deleterious effect of clutter on object recognition) to the precision of saccadic eye movements. Here we examine whether these variations can be attributed to a common source within the visual system. We first compared the size of crowding zones with the precision of saccades using an oriented clock target and two adjacent flanker elements. We report that …

Softening The Blow Of Social Exclusion: The Responsive Theory Of Social Exclusion, Gili Freedman, Kipling D. Williams, Jennifer S. Beer

Dartmouth Scholarship

Social exclusion is an interactive process between multiple people, yet previous research has focused almost solely on the negative impacts on targets. What advice is there for people on the other side (i.e., sources) who want to minimize its negative impact and preserve their own reputation? To provide an impetus for research on the interactive nature of exclusion, we propose the Responsive Theory of Social Exclusion. Our theory postulates that targets and sources’ needs are better maintained if sources use clear, explicit verbal communication. We propose that sources have three options: explicit rejection (clearly stating no), ostracism (ignoring), and ambiguous …

Meditative Movement As A Treatment For Pulmonary Dysfunction In Flight Attendants Exposed To Second-Hand Cigarette Smoke: Study Protocol For A Randomized Trial, Peter Payne, David Zava, Steven Fiering, Mardi Crane-Godreau

Dartmouth Scholarship

A study protocol is presented for the investigation of meditative movement (MM) as a treatment for pulmonary dysfunction in ight attendants (FA) who were exposed to second-hand cigarette smoke while ying before the smoking ban. The study will have three parts, some of which will run concurrently. The rst is a data gathering and screen- ing phase, which will gather data on pulmonary and other aspects of the health of FA, and will also serve to screen participants for the other phases. Second is an exercise selection phase, in which a variety of MM exercises will be taught, over a …

Visual Search Of Mooney Faces, Jessica E. Goold, Ming Meng

Dartmouth Scholarship

Faces spontaneously capture attention. However, which special attributes of a face underlie this effect is unclear. To address this question, we investigate how gist information, specific visual properties and differing amounts of experience with faces affect the time required to detect a face. Three visual search experiments were conducted investigating the rapidness of human observers to detect Mooney face images. Mooney images are two-toned, ambiguous images. They were used in order to have stimuli that maintain gist information but limit low-level image properties. Results from the experiments show: (1) Although upright Mooney faces were searched inefficiently, they were detected more …

Reconstructing Representations Of Dynamic Visual Objects In Early Visual Cortex, Edmund Chong, Ariana M. Familiar, Won Mok Shim

Dartmouth Scholarship

As raw sensory data are partial, our visual system extensively fills in missing details, creating enriched percepts based on incomplete bottom-up information. Despite evidence for internally generated representations at early stages of cortical processing, it is not known whether these representations include missing information of dynamically transforming objects. Long-range apparent motion (AM) provides a unique test case because objects in AM can undergo changes both in position and in features. Using fMRI and encoding methods, we found that the “intermediate” orientation of an apparently rotating grating, never presented in the retinal input but interpolated during AM, is reconstructed in population-level, …

Distinct Effects Of Contrast And Color On Subjective Rating Of Fearfulness, Zhengang Lu, Bingbing Guo, Anne Boguslavsky, Marcus Cappiello, Weiwei Zhang, Ming Meng

Dartmouth Scholarship

Natural scenes provide important affective cues for observers to avoid danger. From an adaptationist perspective, such cues affect the behavior of the observer and shape the evolution of the observer’s response. It is evolutionarily significant for individuals to extract affective information from the environment as quickly and as efficiently as possible. However, the nearly endless variations in physical appearance of natural scenes present a fundamental challenge for perceiving significant visual information. How image-level properties, such as contrast and color, influence the extraction of affective information leading to subjective emotional perception is unclear. On the one hand, studies have shown that …

Through A Glass Darkly: Facial Wrinkles Affect Our Processing Of Emotion In The Elderly, Maxi Freudenberg, Reginald B. Adams, Robert E. Kleck, Ursula Hess

Dartmouth Scholarship

The correct interpretation of emotional expressions is crucial for social life. However, emotions in old relative to young faces are recognized less well. One reason for this may be decreased signal clarity of older faces due to morphological changes, such as wrinkles and folds, obscuring facial displays of emotions. Across three experiments, the present research investigates how misattributions of emotions to elderly faces impair emotion discrimination. In a preliminary task, neutral expressions were perceived as more expressive in old than in young faces by human raters (Experiment 1A) and an automatic system for emotion recognition (Experiment 1B). Consequently, task difficulty …

Inversion Effects Reveal Dissociations In Facial Expression Of Emotion, Gender, And Object Processing, Pamela M. Pallett, Ming Meng

Dartmouth Scholarship

To distinguish between high-level visual processing mechanisms, the degree to which holistic processing is involved in facial identity, facial expression, and object perception is often examined through measuring inversion effects. However, participants may be biased by different experimental paradigms to use more or less holistic processing. Here we take a novel psychophysical approach to directly compare human face and object processing in the same experiment, with face processing broken into two categories: variant properties and invariant properties as they were tested using facial expressions of emotion and gender, respectively. Specifically, participants completed two different perceptual discrimination tasks. One involved making …

The Effect Of Altruistic Tendency On Fairness In Third-Party Punishment, Lu Sun, Peishan Tan, You Cheng, Jingwei Chen, Chen Qu

Dartmouth Scholarship

Third-party punishment, as an altruistic behavior, was found to relate to inequity aversion in previous research. Previous researchers have found that altruistic tendencies, as an individual difference, can affect resource division. Here, using the event-related potential (ERP) technique and a third-party punishment of dictator game paradigm, we explored third-party punishments in high and low altruists and recorded their EEG data. Behavioral results showed high altruists (vs. low altruists) were more likely to punish the dictators in unfair offers. ERP results revealed that patterns of medial frontal negativity (MFN) were modulated by unfairness. For high altruists, high unfair offers (90:10) elicited …

Belief About Nicotine Selectively Modulates Value And Reward Prediction Error Signals In Smokers, Xiaosi Gu, Terry Lohrenz, Ramiro Salas, Philip R. Baldwin, Alireza Soltani

Dartmouth Scholarship

Little is known about how prior beliefs impact biophysically described processes in the presence of neuroactive drugs, which presents a profound challenge to the understanding of the mechanisms and treatments of addiction. We engineered smokers' prior beliefs about the presence of nicotine in a cigarette smoked before a functional magnetic resonance imaging session where subjects carried out a sequential choice task. Using a model-based approach, we show that smokers' beliefs about nicotine specifically modulated learning signals (value and reward prediction error) defined by a computational model of mesolimbic dopamine systems. Belief of "no nicotine in cigarette" (compared with "nicotine in …

Pupil Dilation Dynamics Track Attention To High-Level Information, Olivia E. Kang, Katherine E. Huffer, Thalia P. Wheatley

Dartmouth Scholarship

It has long been thought that the eyes index the inner workings of the mind. Consistent with this intuition, empirical research has demonstrated that pupils dilate as a consequence of attentional effort. Recently, Smallwood et al. (2011) demonstrated that pupil dilations not only provide an index of overall attentional effort, but are time-locked to stimulus changes during attention (but not during mind-wandering). This finding suggests that pupil dilations afford a dynamic readout of conscious information processing. However, because stimulus onsets in their study involved shifts in luminance as well as information, they could not determine whether this coupling of stimulus …

Bursts And Heavy Tails In Temporal And Sequential Dynamics Of Foraging Decisions, Kanghoon Jung, Hyeran Jang, Jerald D. D. Kralik, Jaeseung Jeong

Dartmouth Scholarship

A fundamental understanding of behavior requires predicting when and what an individual will choose. However, the actual temporal and sequential dynamics of successive choices made among multiple alternatives remain unclear. In the current study, we tested the hypothesis that there is a general bursting property in both the timing and sequential patterns of foraging decisions. We conducted a foraging experiment in which rats chose among four different foods over a continuous two-week time period. Regarding when choices were made, we found bursts of rapidly occurring actions, separated by time-varying inactive periods, partially based on a circadian rhythm. Regarding what was …