Psychology

This article provides an overview of our ongoing research project to better understand and formally represent the sociocognitive processes employed in sociodramatic pretend play. Pretend play involves the collaborative cocreation and subsequent enactment of a narrative experience using physical objects. This paper describes our empirical study of human pretend play, including preliminary results; the computational representations of those initial findings; and the design of the Co-creative Cognitive Architecture (CoCoA), a set of components that support the design of co-creative intelligent agents.

The present study aimed to identify predictors of one aspect of sign language acquisition, sign learning, in hearing nonsigners. Candidate predictors were selected based on the theory that the observed relationship between phonological short-term memory and L2 lexical learning is due in part to common perceptual-motor processes. Hearing nonsigning adults completed a sign learning task, three assessments of short-term memory for movements (movement STM)- two of which used sign-like stimuli-and two visuospatial STM tasks. The final sample included 103 adults, ranging between 18 and 33 years of age. All predictors were moderately to strongly correlated with the sign learning task and to each other. A series of regression analyses revealed that both movement and visuospatial STM uniquely contributed to the prediction of sign learning. These results suggest that perceptual-motor processes play a significant role in sign learning and raise questions about the role of phonological processing.

This work is dedicated to the memories of my grandparents, Mary and Ernest Gaskins, my uncle, Lloyd J. Davenport, and Dr. Lawrence R. James, whose commitments to knowledge, integrity, and excellence as human beings influenced my life, work, and worldview in ways that defy description. inestimable value of supportive others in unexpectedly difficult times. For this lesson, I owe many thanks to many people. My greatest debt of gratitude is due my family and friends, whose boundless love, support, and faith in me kept me going through even the greatest of challenges. In particular: to my mother, for being my very best friend, and for sharing every sleepless night and struggle-even as she braved her own grave challenges; to my father, for always soothing my fears with a reminder that he knew I could accomplish anything I desired; to Neil, André, and Ernie, for taking care of the important things when I could not, all so that I could pursue my dreams; and to my honorary siblings Michelle, Eythan, Chaunteé, and Patrick for always listening, no matter how late the hour or how long I talked. I love and appreciate you all beyond measure. Throughout this process, I was fortunate to work alongside bright, friendly peers, especially the members of the Contextual Analysis and Situational Assessment Laboratory, whose support kept this process bearable. Among those invaluable colleagues, Dr. Nathan Wiita stood out for stepping up and taking me under his wing the moment I joined the CASA Lab, and being there for me every day since-earning my undying appreciation. I would also like to thank my committee for their insightful,

This work is dedicated to the memories of my grandparents, Mary and Ernest Gaskins, my uncle, Lloyd J. Davenport, and Dr. Lawrence R. James, whose commitments to knowledge, integrity, and excellence as human beings influenced my life, work, and worldview in ways that defy description. inestimable value of supportive others in unexpectedly difficult times. For this lesson, I owe many thanks to many people. My greatest debt of gratitude is due my family and friends, whose boundless love, support, and faith in me kept me going through even the greatest of challenges. In particular: to my mother, for being my very best friend, and for sharing every sleepless night and struggle-even as she braved her own grave challenges; to my father, for always soothing my fears with a reminder that he knew I could accomplish anything I desired; to Neil, André, and Ernie, for taking care of the important things when I could not, all so that I could pursue my dreams; and to my honorary siblings Michelle, Eythan, Chaunteé, and Patrick for always listening, no matter how late the hour or how long I talked. I love and appreciate you all beyond measure. Throughout this process, I was fortunate to work alongside bright, friendly peers, especially the members of the Contextual Analysis and Situational Assessment Laboratory, whose support kept this process bearable. Among those invaluable colleagues, Dr. Nathan Wiita stood out for stepping up and taking me under his wing the moment I joined the CASA Lab, and being there for me every day since-earning my undying appreciation. I would also like to thank my committee for their insightful,

A very basic computational model is proposed to explain two puzzling findings in the time perception literature. First, spontaneous motor actions are preceded by up to 1-2 s of preparatory activity ). Yet, subjects are only consciously aware of about a quarter of a second of motor preparation . Why are they not aware of the early part of preparation? Second, psychophysical findings support the principle of attention prior entry , which states that attended stimuli are perceived faster than unattended stimuli. However, electrophysiological studies reported no or little corresponding temporal difference between the neural signals for attended and unattended stimuli . We suggest that the key to understanding these puzzling findings is to think of onset detection in probabilistic terms. The two apparently paradoxical phenomena are naturally predicted by our signal detection theoretic model.

In an effort to continue the development of methods to understand social cognition, we adopt a technique called conjoint analysis that mathematically deduces preferences from the implied tradeoffs people make when choosing between sets of attributes at varying levels. We asked 101 students to make a series of choices between prospective teammates in a trivia contest who varied on three dimensions relevant to the decisions (education, IQ, experience) and one dimension that was irrelevant (body weight). Although participants stated explicitly that weight had little impact on their decisions, weight actually accounted for more than 25% of the variance in their revealed preferences. Additional analyses demonstrated that participants gave up about 11 IQ points to have a thin rather than overweight teammate. We suggest that conjoint analysis can be a valuable tool for detecting and quantifying the social costs of covert attitudes that are not in sync with overt values.

How do expectations about the identity of a forthcoming visual stimulus influence the neural mechanisms of perceptual decision making in the human brain? Previous investigations into this issue have mostly involved changing the subjects' attentional focus or the behavioral relevance of certain targets but rarely manipulated subjects' prior expectation about the likely identity of the stimulus. Also, because perceptual decisions were often paired with specific motor responses, it has been difficult to dissociate neural activity that reflects perceptual decisions from motor preparatory activity. Here we designed a task in which we induced prior expectations about the direction of a moving-dot pattern and withheld the stimulus-response mapping until the subjects were prompted to respond. In line with current models of perceptual decision making, we found that subjects' performance was influenced by their expectation about upcoming motion direction. The integration of such information into the decision process was reflected by heightened activity in the dorsolateral prefrontal cortex. Activity in this area reflected the degree to which subjects adjusted their decisions based on the prior expectation cue. Furthermore, there was increased effective connectivity between sensory regions (motion-sensitive medial temporal area MTϩ) and dorsolateral prefrontal cortex when subjects had a prior expectation about the upcoming motion direction. Dynamic causal modeling suggested that stimulus expectation modulated both the feedforward and feedback connectivity between MTϩ and prefrontal cortex. These results provide a mechanism of how prior expectations may affect perceptual decision making, namely by changing neural activity in, and sensory drive to, prefrontal areas.

When perceptual decisions are coupled to a specific effector, preparatory motor cortical activity may provide a window into the dynamics of the perceptual choice. Specifically, previous studies have observed a buildup of choice-selective activity in motor regions over time reflecting the integrated sensory evidence provided by visual cortex. Here we ask how this choice-selective motor activity is modified by prior expectation during a visual motion discrimination task. Computational models of decision making formalize decisions as the accumulation of evidence from a starting point to a decision bound. Within this framework, expectation could change the starting point, rate of accumulation, or the decision bound. Using magneto-encephalography in human observers, we specifically tested for changes in the starting point in choice-selective oscillatory activity over motor cortex. Inducing prior expectation about motion direction biased subjects' perceptual judgments as well as the choice-selective motor activity in the 8 -30 Hz frequency range before stimulus onset; the individual strength of these behavioral and neural biases were correlated across subjects. In the absence of explicit expectation cues, spontaneous biases in choice-selective activity were evident over motor cortex. These also predicted eventual perceptual choice and were, at least in part, induced by the choice on the previous trial. We conclude that both endogenous and explicitly induced perceptual expectations bias the starting point of decision-related activity, before the accumulation of sensory evidence.