Competing Motivational Processes: Autonomic Correlates and Behavioral Output
An organism’s willingness to expend energy is highly malleable and responsive to both internal and environmental perturbations. Motivation promotes physiological and behavioral prioritization driven by current needs. Goals associated with motivational states support processes that benefit daily life as well as long-term survival. Organisms are motivated by an expansive set of needs, ranging from balancing low-level metabolic processes to higher-order maintenance of social systems. Often as one motivation increases, organisms will de-prioritize other motivational processes and shift resources towards behavioral and physiological processes associated with current needs. With a focus on hunger, fatigue, and loneliness I will discuss how autonomic physiology can inform our understanding of how organisms prioritize behavior and survive in ever-changing environments.
A Task-Induced Functional Gradient of Adolescent Psychopathology
Scale-free brain activity occurs when a neural time-series has a high degree of self-similarity in the temporal domain, resulting in more smooth-looking fluctuations. Recent findings from human neuroimaging studies suggest that measures of scale-free brain activity can indicate the “health” of complex neural networks. Among these findings is evidence that less scale-free signals are associated with harder tasks, more novel tasks, poorer performance, increased age, and greater symptoms across a broad range of psychopathologies.
We build on this work and examine covariance between psychopathology and patterns of fMRI-based scale-free brain activity in 1,839 adolescents (9-10 years old) during a working memory task. In this study we use the Hurst exponent to measure the degree to which an individual fMRI BOLD time-series is scale-free. We find a hurst-psychopathology gradient which associates less scale-free brains with higher levels of psychopathology and worse working memory performance. This is in line with the expectations of previous research on hurst and psychopathology. We additionally ask how similar the spatial distribution of this gradient map is to spatial patterns of activations associated with psychological and cognitive terms. We find that the hurst-psychopathology gradient is positively correlated to terms related to task-specific cognition and negatively correlated to terms related to cue-response. This suggests that individuals with higher levels of psychopathology “look” like they are engaged more in task specific processing despite having worse performance. In contrast individuals with lower levels of psychopathology “look” like they are less engaged in task-specific processing despite having better performance.
Seeing Fruit on trees: the role of normalization in dynamic feature-linking
Vision, and other senses, must reconstruct a model of the outside world in a way that allows for action. Our nervous system must extrapolate from incomplete and ambiguous information to do so, as in the case of the transformation of the two retinas’ two-dimensional neural representation into a unified model of an ever-changing three-dimensional world.
The capacity for flexible perception is supported by sensory adaptation and attention, which culminate in a bias toward one possible percept over another. Implicit perceptual biases support an advantage for useful percepts from the inherently ambiguous retinal representations. Perceptual grouping is one well-characterized visual outcome that exemplifies biased perception by enhancing perceptual similarity. Until recently, grouped percepts have dominated accounts of ambiguity resolution, leaving other possible biases to be explored.
One published report supports the position that 1) A difference-enhancing bias exists to produce percepts of objects in view that are maximally different; and 2) A normalization account of perceptual grouping may explain dynamical feature-linking. Finally, four experiments are proposed to address A) how the visual system may use normalization to dynamically selects perceptual experience, B) To what extent does normalization acts globally, or locally, C) what is the influence of magnocellular and parvocellular antagonism in resolving ambiguous figures and ground, and D) can attention influence the resolution of ambiguity? Taken together, these data will provide insight into the neural computation the visual system performs on ambiguous representations to produce separable perceptual outcomes under different input statistics.
Do Hering’s sensations determine lexical color categories?
In principle, languages could create lexical color categories that partition color space in culture-specific ways. Nonetheless, the color categories in the lexicons of world languages are strikingly similar. Why is this so? One traditional explanation is based on Hering’s elemental sensations (redness, greenness, blueness and yellowness), which demarcate privileged regions of color space. Several recent studies have challenged the special status of Hering’s sensations. Are they the cause or the by-product of “red”, “green”, “blue” and “yellow” color categories of the Indo-European languages? Here, we describe the results of three studies that address this issue. The first two studies examined the understanding of Hering’s elemental sensations in subjects speaking languages that are missing terms for some of these sensations. Color naming by the Hadza people is sparse and distributed: most speakers do not use terms for all the Hering sensations (or most other basic color categories of IndoEuropean languages), yet each person uses a different subset of the terms. Thus, the language as a whole demonstrates a complete Hering lexicon, though no idiolect does so. Somali-speaking observers use a term “grue” that does not respect the color boundaries of the Hering color terms, and particularly their term for “yellow” often names colors of every hue. A third study examined the elemental sensations in English-speaking deuteranomalous trichromats. Their initial physiological encoding of color differed from that of color-normal observers. Nevertheless, their choices of broadband lights corresponding to the unique and binary hues of Hering’s theory were similar, but not identical, to those of color normal observers. These results highlight the importance of language in mediating color understanding but are inconsistent with the view that culture alone guides color category formation.
Neural signatures of attentional engagement during narratives and its consequences for event memory
The degree to which we are engaged in narratives fluctuates over time. What drives these changes in engagement, and how do they affect what we remember? To address these questions, I will first present evidence from behavioral studies in which individuals continuously reported their level of engagement as they watched a television show or listened to an audio-narrated story. People experienced similar fluctuations of engagement during narratives, and were more engaged during more emotional moments. I will next describe results from two functional MRI experiments demonstrating that changes in a pattern of functional brain connectivity predicted changes in how engaged people were in these same narratives. This predictive “engagement network” not only was related to a validated neuromarker of sustained attention, but also predicted what narrative events people recalled after the MRI scan. Together these findings reveal a robust, generalizable neural signature of attentional engagement in naturalistic contexts and elucidate relationships between narrative engagement, sustained attention, and event memory.
“I’m in an encoding state of mind”: Neural mechanisms of memory formation
How do we successfully form new memories? A classic approach to assessing memory formation is the comparison of activity patterns during the study of items that will later be remembered compared to the study of items that will later be forgotten — a contrast dubbed the subsequent memory effect (SME). Although this approach has been fruitful, there are many reasons why we may forget, meaning that the SME contrast is a coarse assay of memory formation. Here we use alternative approaches in which we refine the SME contrast and investigate the role of mnemonic states in memory formation. We record scalp EEG or fMRI while participants perform memory tasks and use a combination of univariate and multivariate approaches to assess successful memory formation. We find that neural SME signals reflect memory organization processes and that mnemonic states, estimated through multivariate analysis methods, may be better predictors of subsequent memory than traditional univariate signals. A central goal of our future work is to identify the factors that induce mnemonic states and to link the engagement of mnemonic states to performance across cognitive tasks.
Lingua Franca Use as a Hidden Barrier to Conflict Resolution
When international negotiation faces a communication barrier a solution is to use a lingua franca that is native to neither side, presumably putting the parties on equal footing through the use of a common language. Here we show that despite common belief, using a lingua franca erects hidden barriers to conflict resolution. In three studies in which native Hebrew speaking Israelis evaluated an outline for a peace building proposal, they consistently perceived it less favorably when it was in English than when it was presented in their native Hebrew. The use of the lingua franca elicits a less positive emotional response as compared to the use of a native language, thereby reducing how favorably the proposal was evaluated as being for their side. This has implications for cross-national negotiation in diplomacy as well as commerce.
Environmental influences on thought content and connectedness
Exposure to natural environments, compared to urban environments, has generally been shown to be beneficial for positive affect, pro-social thinking, and feelings of
connectedness. As most studies use pre- and post-exposure testing, the time course of these changes in thoughts and feelings is unclear. Additionally, individual differences, such as trait impulsivity, which may mediate the relationship between environmental exposure and changes in affect and cognition, are less well understood. I will present a study where we investigated these questions by surveying participants at three timepoints during a one hour walk in both a natural and urban environment. Our results showed that differences between positive affect and environmental connectedness were detected by the first survey time point (20 minutes), and most differences remained significant throughout the entire walk. We did not replicate the association of trait impulsivity with changes in positive affect. However, exploratory analysis uncovered several other traits that should be further investigated as individual difference measures that may influence whether an individual reaps the benefits of spending time in natural environments.
Description’s role in language and concept learning
Learning from description seems straightforward: if you hear about a “blue dax,” you might think you should learn that daxes are likely to be blue. But, counterintuitively, you should do the opposite. This is because people describe the rare or interesting features of objects, and not their typical features. If you hear about a “blue dax,” it is likely that most daxes are not blue. In this talk, I will draw on corpus analyses of conversation, language modeling, and experiments with adults to suggest that learning from description poses a problem for associative models of language and concept learning. Corpus analyses of parent–child conversations show that when talking to children as young as 14 months old, parents use description to highlight the surprising, atypical features of things (e.g., “brown apple”) rather than their typical, generalizable features (e.g., “red apple”). That is, people remark on features that are surprising given their world knowledge, even when talking to a child whose world knowledge is still nascent. Because language is structured in this way, models of word meaning that associate co-occurring words (here, Word2vec) fail to capture typicality relationships between nouns and adjectives well. Finally, adults take into account that description remarks upon the remarkable when interpreting utterances about novel categories (e.g., “Pass me the blue dax”): they do not simply associate the descriptor with the novel category, but infer that the descriptor points out an atypical feature (e.g., that it is rare for daxes to be blue). Overall, we find that people produce and interpret description based on principles of informative communication—not veridical description of the world—and this raises problems for associative models of language and concept learning as well as natural language processing.
Cognitive Effort and Decision-making: Integrating Computational, Behavioral, And Psychophysiological Approaches
Our ability to perform tasks is constrained by our limited mental resources, which mandates that people should minimize use of cognitively “effortful” processing when possible. Recent theories posit that decisions to expend effort are governed by a cost-benefit tradeoff, whereby the potential benefits of effort can offset its perceived costs. I will present a series of recent, computationally-informed experiments combining behavioural experimentation and pupillometry to gain critical insights into understanding when and why we allocate—or withhold—cognitive effort, both from an individual differences perspective, and at the level of the task by examining the effect of changes in costs and benefits. We find that individual differences in cognitive capacity—and relatedly, intrinsic motivation—govern trial-to-trial adjustments to cognitive effort expenditure in accordance with shifts in costs (i.e., opportunity costs) and benefits (i.e., rewards). Further, we find that task-evoked pupillary responses can elucidate internal computations of these effort allocation decisions.
Predicting functional organization and its impact on behavior
In many ways, cognitive neuroscience is the attempt to use physiological observation to clarify the mechanisms that shape behavior. Over the past 25 years, fMRI has provided a system-wide and yet somewhat spatially precise view of the response in human cortex evoked by a wide variety of stimuli and task contexts. The current talk focuses on the other direction of inference; the implications of this observed functional organization for behavior. To begin, we must interrogate the methodological and empirical frameworks underlying our derivation of this organization, partially by exploring its relationship to and predictability from gross neuroanatomy. Next, across a series of studies, the implications of two properties of functional organization for behavior will be explored: 1) the co-localization of visual working memory and perceptual processing and 2) implicit learning in the context of distributed responses. In sum, these results highlight the limitations of our current approach and hint at a new general mechanism for explaining observed behavior in context with the neural substrate.
The Fall 2020 Cognition Workshop will take place on Wednesdays from 4-5:15pm Central Time via Zoom (login details will be shared before each talk).
Below is the schedule of speakers, who will discuss work in cognitive psychology, neuroscience, and related topics.