Hanna Oh Descher, Ph.D.
Korrina Duffy, Ph.D.
Dissertation Abstract: This describes four studies that broadly explore the personality characteristics, physiological consequences, and neural mechanisms underlying the behavioral mimicry that occurs when people try to affiliate with others in social interactions. I address three research questions: (1) which individuals are more likely to mimic in the presence of an affiliation goal, (2) what are the physiological consequences of mimicking to build affiliation, and (3) what is the neural mechanism underlying top-down control of mimicry? Chapter 1 gives background on the causes and consequences of mimicry in social interactions. Chapter 2 asks whether extraverts mimic more than introverts as a way to build rapport. In two studies, participants were either given an affiliation goal or not before interacting with a confederate. Study 1 tested whether extraverts mimicked more than introverts in the presence of an affiliation goal. Study 2 replicated and expanded on the design of study 1 by assessing whether mimicry mediated the relationship between extraversion and rapport (as measured by an independent observer). Study 1 found that extraversion predicts increased mimicry when an affiliation goal is present but not when an affiliation goal is absent. Study 2 showed that mimicry mediates the relationship between extraversion and rapport but only when an affiliation goal is present. These studies show that the rapport-building ability of extraverts emerges only when they are motivated to affiliate, providing evidence for the reward-sensitivity-as-core model of extraversion over the sociability-as-core model of extraversion. Chapter 3 explored the link between psychological, behavioral, and physiological mechanisms involved in affiliation. In study 3, participants were randomly assigned to experience social rejection or social acceptance before they were given either an opportunity to mimic a confederate (face-to-face interaction) or not (interaction behind barrier). Rejected participants (1) mimicked a confederate significantly more than accepted participants and (2) mimicry significantly mediated the effect of social feedback (rejection vs. acceptance) on progesterone change, such that mimicking was associated with increases in progesterone. The results suggest that mimicry facilitates progesterone release, which provides preliminary evidence of a physiological mechanism by which mimicry exerts its psychological effects of increasing affiliation and decreasing psychosocial distress. In Chapter 4, study 4 directly tested two competing hypotheses on the role of the right temporoparietal junction (rTPJ) in top-down control of mimicry. Participants were randomized to receive either active or sham intermittent theta-burst stimulation (a type of stimulation that increases activation) to the rTPJ in a between-subjects design. After receiving either active or sham iTBS, I measured how much participants mimicked another person in a social interaction. The results show that, for participants in the active stimulation condition, hair and face touching was significantly lower during the social interaction compared to baseline. This finding suggests that higher activation in the rTPJ increases the distinction between representations of self and other, specifically biasing representations of self over other, leading to less mimicry. These results do not support the hypothesis that higher activation in the rTPJ leads to flexible control of self-other representations in line with goals. Chapter 5 provides an overview of the main findings of these studies, discusses how these studies inform one another, and points the field toward open questions for future research.Current Position: Postdoctoral fellow at the National Cancer Institute in the Behavioral Research Program
Jonathan Winkle, Ph.D.
Rosa Li, Ph.D.
Current Position: Postdoctoral associate in Decision Sciences at Duke (D-CIDES)
Amanda Utevsky, Ph.D.
Nathan Clement, Ph.D.
Emma Wu Dowd, Ph.D.
Jessica K. Stanek, Ph.D.
The present findings demonstrated that novelty and expectancy violation both drive dopaminergic circuitry capable of contributing to memory formation. Consistent with elevated dopaminergic midbrain and hippocampus activation for each, expected versus expectancy violating novelty did not differentially impact memory success. We also showed that high curiosity expectancy states drive memory formation. This was supported by activation in dopaminergic circuitry that was greater for subsequently remembered information only in the high curiosity state. Finally, we showed that cues that generate high expected reward value versus high reward uncertainty differentially modulate memory formation during reward anticipation. This behavioral result was consistent with distinct temporal profiles of dopaminergic action having differential downstream effects on episodic memory formation.
Integrating the present studies with previous research suggests that dopaminergic circuitry signals events that are unpredicted, whether cuing or resolving expectations. It also suggests that contextual differences change the contribution of the dopaminergic system during anticipation, depending on the nature of the expectation. And finally, this work is consistent with a model in which dopamine elevation in response to expectancy events positively modulates episodic memory formation.
Current Position: Clinical Research Study Manager, Institute for Trauma Recovery, Department of Anesthesiology, University of North Carolina at Chapel Hill
Caroline Drucker, Ph.D.
Joseph Barter, Ph.D.
Jeff MacInnes, Ph.D.
Courtnea Rainey, Ph.D.
Heather Mann, Ph.D.
Jiefeng Jiang, Ph.D.
Kait Clark, Ph.D.
Dissertation Abstract: Visual search, the process of detecting relevant items within an environment, is a vital skill required for navigating one’s visual environment as well as for careers, such as radiology and airport security, that rely upon accurate searching. Research over the course of several decades has established that visual search requires the integration of low- and high-level cognitive processes, including sensory analysis, attentional allocation, target discrimination, and decision-making. Search abilities are malleable and vary in accordance with long-term experiences, direct practice, and contextual factors in the immediate environment; however, the mechanisms responsible for changes in search performance remain largely unclear. A series of studies examine variation in visual search abilities and performance and aim to identify the underlying mechanisms. To assess differences associated with long-term experiences, visual search performance is compared between laypersons (typically undergraduates) and specific populations, including radiologists and avid action video game players. Behavioral markers of search processes are used to elucidate causes of enhanced search performance. To assess differences associated with direct practice, laypersons perform a visual search task over five consecutive days, and electrophysiological activity is recorded from the scalp on the first and last days of the protocol. Electrophysiological markers associated with specific stages of processing are analyzed to determine neurocognitive changes contributing to improved performance. To assess differences associated with contextual factors, laypersons are randomly assigned to experimental conditions in which they complete a visual search task within a particular framework or in the presence or absence of motivation, feedback, and/or time pressure. Results demonstrate that search abilities can improve through experience and direct training, but the mechanisms underlying effects in each case are different. Long-term experiences are associated with strategic attentional allocation, but direct training can improve low-level sensory analysis in addition to higher-level processes. Results also demonstrate nuanced effects of experience and context. On searches that contain multiple targets, task framework impacts accuracy for detecting additional targets after one target has been identified. The combination of motivation and feedback enhances accuracy for both single- and multiple-target searches. Implications for cognitive theory and applications to occupational protocols are discussed.
Current Position: Postdoctoral research associate, Simon Rushton lab, Cardiff University, Wales
Amy Winecoff, Ph.D.
Jessica Lake, Ph.D.
Nick DeWind, Ph.D.
David Barack, Ph.D.
R. Becket Ebitz, Ph.D.
Joseph A. Harris, Ph.D.
Dissertation Abstract: Any information represented in the brain, whether an individual is aware of it or not, holds the potential to affect behavior. The extent of visual perceptual processing that occurs in the absence of awareness is therefore a question of broad import and interest to the field of cognitive neuroscience. A useful approach for examining the extent and quality of visual processing that occurs in the absence of awareness is the dissociation paradigm. In this approach, experimenters track implicit measures of the visual process of interest across conditions of awareness modulated by visual presentation manipulations. Object-category discrimination by the visual system represents a relatively sophisticated level of representation that may or may not occur in the absence of awareness. Here, electrophysiological measures (scalp-recorded event-related potentials, or ERPs) of object-category discrimination by the brain (the face-specific N170 ERP component and the longer-latency face-specific negativity) were tracked across conditions of visual awareness as manipulated by multiple presentation paradigms (sandwich masking, object-substitution masking, the attentional blink, and motion-induced blindness). In addition, where possible, other related comparisons examining lower-level visual processes and higher-level attentional processes were employed to help delineate the specific level and mechanism by which awareness was disrupted in each case. The experiments implicated a unique set of mechanisms of reducing awareness for each method, while providing insight into the complex relationships between the various phases of visual processing in the human brain and awareness. Ultimately it was observed that neural indices of face-specific processing are differentially susceptible to disruption exerted by these various methods, and that there do in fact exist conditions in which awareness can be disrupted while leaving various facets and phases of face-specific processing intact. These findings help to establish object-category discrimination as a process that can occur in the absence of visual awareness, and contributes to our understanding of the neural factors that influence and determine behavior.
Current Position: Postdoctoral researcher, Otto-von-Guericke-Universität Magdeburg / Leibinz Institutute for Neurobiology in Magdeburg, Germany
Sarah E. Donohue, Ph.D.
Dissertation Abstract: At every moment in life we are receiving input from multiple sensory modalities. We are limited, however, in the amount of information we can selectively attend to and fully process at any one time. The ability to integrate the relevant corresponding multisensory inputs together and to segregate other sensory information that is conflicting or distracting is therefore fundamental to our ability to successfully navigate through our complex environment. Such multisensory integration and segregation is done on the basis of temporal, spatial, and semantic cues, often aided by selective attention to particular inputs from one or multiple modalities. The precise nature of how attention interacts with multisensory perception, and how this ramifies behaviorally and neurally, has been largely underexplored. Here, in a series of six cognitive experiments in humans using auditory and visual stimuli, along with electroencephalography (EEG) measures of brain activity and behavioral measures of task performance, I examine the interactions between attention, stimulus conflict, and multisensory processing. I demonstrate that attention can spread across modalities in a pattern that closely follows the temporal linking of multisensory stimuli, while also engendering the spatial linking of such multisensory stimuli. When stimulus inputs either within audition or across modalities conflict, I observe an electrophysiological signature of the processing of this conflict that is similar to what had been previously observed within the visual modality. Moreover, using neural measures of attentional distraction, I show that when task-irrelevant stimulus input from one modality conflicts with task-relevant input from another, attention is initially pulled toward the conflicting irrelevant modality, thereby contributing to the observed impairment in task performance. Finally, I demonstrate that there are individual differences in multisensory temporal processing in the population, in particular between those with extensive action-video-game experience versus those with little. However, everyone appears to be susceptible to multisensory distraction, a finding that should be taken into serious consideration in today’s complex world of multitasking.
Current Position: Postdoctoral researcher, Otto-von-Guericke-Universität Magdeburg / Leibinz Institutute for Neurobiology in Magdeburg, Germany
David V. Smith, Ph.D.
Daniel L. Bowling, Ph.D.
Dissertation Abstract: In most aspects of music—e.g., tempo, intensity, and rhythm—the emotional coloring of a melody is due at least in part to physical imitation of the characteristics of emotional expression in human behavior. Thus excited, happy melodies are fast and loud, with syncopated rhythms, whereas subdued sad melodies are slow and quiet, with more even rhythms. The tonality of a melody (e.g. major or minor) also conveys emotion, but unlike other aspects of music, the basis for its affective impact is not clear. This thesis examines the hypothesis that different collections of musical tones are associated with specific emotions because they mimic the natural relationship between emotion and tonality present in the human voice. To evaluate this possibility, I have conducted acoustical analyses on databases of music and speech drawn from a variety of cultures, and compared the tonal characteristics of emotional expression between these two forms of social communication. I find that: (1) the melodic characteristics of music and the prosodic characteristics of speech co-vary when examined across cultures; (2) the principal tonal characteristics of melodies composed in tonalities associated with positive/excited emotion and negative/subdued emotion are much the same in different cultures; (3) cross-cultural tonal similarities in music parallel cross-cultural tonal similarities in vocal expression; and (4) the tonal characteristics of emotional expression in the voice convey distinct emotions, thereby accounting for the specificity of emotional association in musical tonality. These findings, and the implausibility of alternative explanations that could account for them, suggest that the affective impact of musical tonality derives from mimicry of the tonal characteristics of vocalization in different emotional states.
Current Position: Postdoctoral researcher, Department of Cognitive Biology, Vienna
Sarah Heilbronner, Ph.D.
Vishnu "Deepu" Murty, Ph.D.
Dissertation Abstract: Memories are not veridical representations of the environment. Rather, an individual’s goals can influence how the surrounding environment is represented in long-term memory. The present dissertation aims to delineate the influence of reward and punishment motivation on human declarative memory encoding and its underlying neural circuitry. Chapter 1 provides a theoretical framework for investigating the influence of motivation on declarative memory. This chapter will review the animal and human literatures on declarative memory encoding, reward and punishment motivation, and the influence of motivation on learning and memory. Chapter 2 presents a study examining the behavioral effects of reward and punishment motivation on declarative memory encoding. Chapter 3 presents a study examining the neural circuitry underlying punishment-motivated declarative encoding using functional magnetic resonance imaging (fMRI), and compares these findings to previous studies of reward-motivated declarative encoding. Chapter 4 presents a study examining the influence of reward and punishment motivation on neural sensitivity to and declarative memory for unexpected events encountered during goal pursuit using fMRI. Finally, Chapter 5 synthesizes these results and proposes a model of how and why motivational valence has distinct influences on declarative memory encoding. Results indicated that behaviorally, reward motivation resulted in more enriched representations of the environment compared to punishment motivation. Neurally, these motivational states engaged distinct neuromodulatory systems and medial temporal lobe (MTL) targets during encoding. Specifically, results indicated that reward motivation supports interactions between the ventral tegmental area and the hippocampus, whereas, punishment motivation supports interactions between the amygdala and parahippocampal cortex. Together, these findings suggest that reward and punishment engage distinct systems of encoding and result in the storage of qualitatively different representations of the environment into long-term memory.
Current Position: Postdoctoral fellowship with Lila Davachi, New York University
Alexandra Rosati, Ph.D.
Dissertation Abstract: Abstract: Primates in the wild face complex foraging decisions where they must assess the most valuable of different potential resources to exploit, as well recall the location of options that can be widely distributed. While differences in diet and ecology have long been thought to be an important factor influencing brain evolution in primates, it is less well understood what psychological abilities animals actually use when making foraging decisions. This dissertation examines cognitive domains that play a crucial role in supporting foraging behaviors—spatial memory and decision-making—by integrating both psychological and biological approaches to behavior. In particular, the research presented here examines multiple species of primates to address the cognitive skills that different animals use to solve foraging problems (at the proximate level of analysis), as well as why some species appear to solve such problems differently than other species (at the ultimate level of analysis). The first goal of the dissertation is to compare closely-related species that vary in ecological characteristics, in order to illuminate how evolution shapes the cognitive skills used in foraging contexts. This component focuses on comparisons of spatial memory and decision-making strategies between chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), humans’ closest extant relatives. In addition, I report comparisons of memory skills amongst strepsirrhines (Lemur catta, Eulemur mongoz, Propithecus coquereli, and Varecia subsp.) to model cognitive evolution in a taxonomic group with greater ecological diversity than Pan. The second goal of the dissertation is to compare the psychological mechanisms that human and nonhuman great apes use for foraging, in order to identify potentially human-unique cognitive abilities. In terms of spatial memory, I examine whether other apes also exhibit human-like patterns of spatial memory development. In terms of decision-making, I examine whether apes exhibit a suite of human-like biases when making value-based choices about time, risk, and ambiguity. Finally, I directly compare human and ape preferences on a matched task to assess whether humans use any unique psychological abilities when making decisions about risk. In sum, this dissertation links studies of mechanism with hypotheses about function in order to illuminate the evolutionary roots of human's unique cognitive phenotype.
Current Position: Assistant professor, Department of Human Evolutionary Biology, Harvard University
Vinod Venkatraman, Ph.D.
Dissertation Abstract: We make a variety of decisions throughout our lives. Some decisions involve outcomes whose values can be readily compared, especially when those outcomes are simple, immediate, and familiar. Other decisions involve imperfect knowledge about their potential consequences: Should I accept the job offer I have now or wait for a possible better offer in the future? Understanding the choice process when consequences are uncertain – often called the study of decision making under risk – has been the focus of research in behavioral economics, cognitive psychology, and now neuroscience. Hallmark of human decision making is the ability to use multiple strategies in representing and evaluating complex decision problems, and to flexibly adapt these strategies to contextual changes in the environment. Yet, little is known about the mechanisms underlying this flexible use of strategies, both across individuals as well as decision contexts. I propose a hypothetical model of cognitive control that is primarily characterized by hierarchical interactions – whose level depends on current environmental demands – between functional subdivisions of medial and lateral PFC.
Current Position: Assistant Professor, Department of Marketing, Fox School of Business, Temple University
Maureen Ritchey, Ph.D.
Dissertation Abstract: Emotion is known to influence multiple aspects of memory formation, which may include the initial encoding of the memory trace, its consolidation over time, and the efficacy of its retrieval. However, prior investigations have tended to treat emotional modulation of episodic memory as a unitary construct, thus conflating the contributions of these different stages to emotion-mediated memory enhancements. The present thesis aims to disentangle the component processes of emotional memory formation and retrieval through a series of studies using cognitive behavioral and functional magnetic resonance imaging (fMRI) methods. In the first 2 studies, neural activity was evaluated during the initial viewing of emotionally arousing and neutral scenes and, in the 3rd study, neural activity during this initial viewing period was compared to that during a recognition memory task. The findings are compatible with the proposal that two distinct networks support successful emotional memory formation: an amygdala-medial temporal lobe (MTL) network that modulates the consolidation of memories over time and a prefrontal-MTL network that translates emotion effects on controlled elaboration into superior memory encoding. The superlative quality of emotional memories is furthermore marked by heightened similarity between neural states at encoding and retrieval, suggesting another line of evidence through which emotion effects can be observed. Taken together, the results presented here highlight the heterogeneity of processes that confer mnemonic advantages to emotionally significant information.
Current Position: Postdoctoral Scholar, Center for Neuroscience, University of California, Davis