Crossmodal correspondences as common ground for joint action

Distinguishing between straight and curved sounds: Auditory shape in pitch, loudness, and tempo gestures

Sound-based trajectories or sound gestures draw links to spatiokinetic processes. For instance, a gliding, decreasing pitch conveys an analogous downward motion or fall. Whereas the gesture's pitch orientation and range convey its meaning and magnitude, respectively, the way in which pitch changes over time can be conceived of as gesture shape, which to date has rarely been studied in isolation. This article reports on an experiment that studied the perception of shape in uni-directional pitch, loudness, and tempo gestures, each assessed for four physical scalings. Gestures could increase or decrease over time and comprised different frequency and sound level ranges, durations, and different scaling contexts. Using a crossmodal-matching task, participants could reliably distinguish between pitch and loudness gestures and relate them to analogous visual line segments. Scalings based on equivalent-rectangular bandwidth (ERB) rate for pitch and raw signal amplitude for loudness were matched closest to a straight line, whereas other scalings led to perceptions of exponential or logarithmic curvatures. The investigated tempo gestures, by contrast, did not yield reliable differences. The reliable, robust perception of gesture shape for pitch and loudness has implications on various sound-design applications, especially those cases that rely on crossmodal mappings, e.g., visual analysis or control interfaces like audio waveforms or spectrograms. Given its perceptual relevance, auditory shape appears to be an integral part of sound gestures, while illustrating how crossmodal correspondences can underpin auditory perception.

Understanding joint action: Current theoretical and empirical approaches

Joint actions are omnipresent, ranging from a handshake between two people to the coordination of groups of people playing in an orchestra. We are highly skilled at coordinating our actions with those of others to reach common goals and rely on this ability throughout our daily lives. What are the social, cognitive and neural processes underlying this ability? How do others around us influence our task representations? How does joint action influence interpersonal interactions? How do language and gesture support joint action? What differentiates joint action from individual action? This article forms an introductory editorial to the field of joint action. It accompanies contributions to the special issue entitled "Current Issues in Joint Action Research". The issue brings together conceptual and empirical approaches on different topics, ranging from lower-level issues such as the link between perception and joint action, to higher-level issues such as language as a form of joint action.