Staying Together: A Bidirectional Delay–Coupled Approach to Joint Action

To understand how individuals adapt to and anticipate each other in joint tasks, we employ a bidirectional delay–coupled dynamical system that allows for mutual adaptation and anticipation. In delay–coupled systems, anticipation is achieved when one system compares its own time‐delayed behavior, which implicitly includes past information about the other system’s behavior, with the other system’s instantaneous behavior. Applied to joint music performance, the model allows each system to adapt its behavior to the dynamics of the other. Model predictions of asynchrony between two simultaneously produced musical voices were compared with duet pianists’ behavior; each partner performed one voice while auditory feedback perturbations occurred at unpredictable times during live performance. As the model predicted, when auditory feedback from one musical voice was removed, the asynchrony changed: The pianist’s voice that was removed anticipated (preceded) the actions of their partner. When the auditory feedback returned and both musicians could hear each other, they rapidly returned to baseline levels of asynchrony. To understand how the pianists anticipated each other, their performances were fitted by the model to examine change in model parameters (coupling strength, time‐delay). When auditory feedback for one or both voices was removed, the fits showed the expected decrease in coupling strength and time‐delay between the systems. When feedback about the voice(s) returned, the coupling strength and time‐delay returned to baseline. These findings support the idea that when people perform actions together, they do so as a coupled bidirectional anticipatory system.     

Terror Management and Personality: Variations in the Psychological Defense Against the Awareness of Mortality

Drawing on terror management theory (TMT), we discuss the psychological motivations that shape personality at two levels: the characteristically human personality common to us all and the individual differences that distinguish some people from others. TMT posits that the motivation to protect the self against deep-rooted fears about mortality drives people to maintain meaningful, reliable conceptions of reality and positive evaluations of themselves, two broad tendencies that form the foundation of every person’s personality. We review studies showing that mortality reminders increase efforts to bolster cultural sources of meaning and self-esteem in similar ways across individuals and cultures. TMT also posits that individual differences in personality partly reflect the different sources of meaning and self-esteem that people invest in to assuage mortality fears. We review evidence that individual differences predict the degree and direction of people’s defensive responses to mortality reminders. Directions for future research are discussed.