Drew H. Abney

Complexity matching in dyadic conversation

Recent studies of dyadic interaction have examined phenomena of synchronization, entrainment, alignment, and convergence. All these forms of behavioral matching have been hypothesized to play a supportive role in establishing coordination and common ground between interlocutors. In the present study, evidence is found for a new kind of coordination termed complexity matching. Temporal dynamics in conversational speech signals were analyzed through time series of acoustic onset events. Timing in periods of acoustic energy was found to exhibit behavioral matching that reflects complementary timing in turn-taking. In addition, acoustic onset times were found to exhibit power law clustering across a range of timescales, and these power law functions were found to exhibit complexity matching that is distinct from behavioral matching. Complexity matching is discussed in terms of interactive alignment and other theoretical principles that lead to new hypotheses about information exchange in dyadic conversation and interaction in general.

Movement dynamics reflect a functional role for weak coupling and role structure in dyadic problem solving.

Successful interaction requires complex coordination of body movements. Previous research has suggested a functional role for coordination and especially synchronization (i.e., time-locked movement across individuals) in different types of human interaction contexts. Although such coordination has been shown to be nearly ubiquitous in human interaction, less is known about its function. One proposal is that synchrony supports and facilitates communication (Topics Cogn Sci 1:305–319, 2009). However, questions still remain about what the properties of coordination for optimizing communication might look like. In the present study, dyads worked together to construct towers from uncooked spaghetti and marshmallows. Using cross-recurrence quantification analysis, we found that dyads with loosely coupled gross body movements performed better, supporting recent work suggesting that simple synchrony may not be the key to effective performance (Riley et al. 2011). We also found evidence that leader–follower dynamics—when sensitive to the specific role structure of the interaction—impact task performance. We discuss our results with respect to the functional role of coordination in human interaction.

Using nonlinear methods to quantify changes in infant limb movements and vocalizations.

The pairing of dynamical systems theory and complexity science brings novel concepts and methods to the study of infant motor development. Accordingly, this longitudinal case study presents a new approach to characterizing the dynamics of infant limb and vocalization behaviors. A single infants vocalizations and limb movements were recorded from 51-days to 305-days of age. On each recording day, accelerometers were placed on all four of the infants limbs and an audio recorder was worn on the childs chest. Using nonlinear time series analysis methods, such as recurrence quantification analysis and Allan factor, we quantified changes in the stability and multiscale properties of the infants behaviors across age as well as how these dynamics relate across modalities and effectors. We observed that particular changes in these dynamics preceded or coincided with the onset of various developmental milestones. For example, the largest changes in vocalization dynamics preceded the onset of canonical babbling. The results show that nonlinear analyses can help to understand the functional co-development of different aspects of infant behavior.

Influence of musical groove on postural sway.

Timescales of postural fluctuation reflect underlying neuromuscular processes in balance control that are influenced by sensory information and the performance of concurrent cognitive and motor tasks. An open question is how postural fluctuations entrain to complex environmental rhythms, such as in music, which also vary on multiple timescales. Musical groove describes the property of music that encourages auditory-motor synchronization and is used to study voluntary motor entrainment to rhythmic sounds. The influence of groove on balance control mechanisms remains unexplored. We recorded fluctuations in center of pressure (CoP) of standing participants (N = 40) listening to low and high groove music and during quiet stance. We found an effect of musical groove on radial sway variability, with the least amount of variability in the high groove condition. In addition, we observed that groove influenced postural sway entrainment at various temporal scales. For example, with increasing levels of groove, we observed more entrainment to shorter, local timescale rhythmic musical occurrences. In contrast, we observed more entrainment to longer, global timescale features of the music, such as periodicity, with decreasing levels of groove. Finally, musical experience influenced the amount of postural variability and entrainment at local and global timescales. We conclude that groove in music and musical experience can influence the neural mechanisms that govern balance control, and discuss implications of our findings in terms of multiscale sensorimotor coupling. (PsycINFO Database Record

Joint perceptual decision-making: a case study in explanatory pluralism

Traditionally different approaches to the study of cognition have been viewed as competing explanatory frameworks. An alternative view, explanatory pluralism, regards different approaches to the study of cognition as complementary ways of studying the same phenomenon, at specific temporal and spatial scales, using appropriate methodological tools. Explanatory pluralism has been often described abstractly, but has rarely been applied to concrete cases. We present a case study of explanatory pluralism. We discuss three separate ways of studying the same phenomenon: a perceptual decision-making task (Bahrami et al., 2010), where pairs of subjects share information to jointly individuate an oddball stimulus among a set of distractors. Each approach analyzed the same corpus but targeted different units of analysis at different levels of description: decision-making at the behavioral level, confidence sharing at the linguistic level, and acoustic energy at the physical level. We discuss the utility of explanatory pluralism for describing this complex, multiscale phenomenon, show ways in which this case study sheds new light on the concept of pluralism, and highlight good practices to critically assess and complement approaches.

Response dynamics in prospective memory

Prospective memory (PM) is the ability to remember to execute a delayed behavior. Most theoretical and empirical work on PM has focused on the attentional resources that might facilitate successfully executing a delayed behavior. In the present study, we enhance the current understanding of attention allocation and also introduce novel evidence for the dynamics of PM retrieval. We recorded mouse-tracking trajectories during a prospective memory task to examine the continuous nature of attentional processes that support PM cue retrieval. We found that the velocity profiles of response trajectories differed as a function of PM cue focality while controlling for the canonical measure of response time, supporting the notions that monitoring is evident in the continuous nature of response trajectories and that such trajectories are sensitive to cue focality. Conditional velocity profiles of ongoing task trials indicated that monitoring occurred when the processing of PM cues differed from ongoing task instructions (Nonfocal PM condition): responses were made later in the profile, suggestive of a more controlled retrieval process. Analysis of PM cue retrieval profiles indicated correctly retrieved Focal PM cues were qualitatively and quantitatively different from all other PM cue retrieval trials. This provides evidence that retrieval dynamics of a delayed behavior differ as a function of cue focality and suggests that controlled processing may contribute to spontaneous retrieval of a PM task.

Interactive effects in transfer-appropriate processing for event-based prospective memory: The roles of effort, ongoing task, and PM cue properties

Past studies (e.g., Marsh, Hicks, & Cook Journal of Experimental Psychology: Learning, Memory, and Cognition 31:68–75, 2005; Meiser & Schult European Journal of Cognitive Psychology 20:290–311, 2008) have shown that transfer-appropriate processing (TAP) effects in event-based prospective memory (PM) depend on the effort directed toward the ongoing task. In the present study, we addressed mixed findings from these studies and examined monitoring in TAP and transfer-inappropriate processing (TIP) conditions. In two experiments, a semantic or orthographic ongoing task was paired with a PM cue that either was matched in processing (TAP) or did not match in processing (TIP). Within each condition, effort was varied across trials. The results indicated that PM accuracy was higher in TAP than in TIP conditions, regardless of effort condition, supporting the findings reported by Meiser and Schult. Ex-Gaussian functions were fit to the mean reaction times (cf. Brewer Journal of Psychology 219:117–124, 2011) in order to examine monitoring across conditions. The analysis of distributional skew (τ parameter) showed sensitivity to ongoing task instructions and properties of the PM cues. These results support Meiser and Schult’s suggestion that TIP conditions require more attentional processing, and they also afford novel discussion on the interactive effects of ongoing task condition, PM cue properties, and manipulations of effort.

Transfer of recalibration from audition to touch: modality independence as a special case of anatomical independence.

An important step in developing a theory of calibration is establishing what it is that participants become calibrated to as a result of feedback. Three experiments used a transfer of calibration paradigm to investigate this issue. In particular, these experiments investigated whether recalibration of perception of length transferred from audition to dynamic (i.e., kinesthetic) touch when objects were grasped at one end (Experiment 1), when objects were grasped at one end and when they were grasped at a different location (i.e., the middle) (Experiment 2), and when false (i.e., inflated) feedback was provided about object length (Experiment 3). In all three experiments, there was a transfer of recalibration of perception of length from audition to dynamic touch when feedback was provided on perception by audition. Such results suggest that calibration is not specific to a particular perceptual modality and are also consistent with previous research that perception of object length by audition and dynamic touch are each constrained by the objects mechanical properties.

Multiple Coordination Patterns in Infant and Adult Vocalizations

The study of vocal coordination between infants and adults has led to important insights into the development of social, cognitive, emotional and linguistic abilities. We used an automatic system to identify vocalizations produced by infants and adults over the course of the day for fifteen infants studied longitudinally during the first two years of life. We measured three different types of vocal coordination: coincidence-based, rate-based, and cluster-based. Coincidence-based and rate-based coordination are established measures in the developmental literature. Cluster-based coordination is new and measures the strength of matching in the degree to which vocalization events occur in hierarchically nested clusters. We investigated whether various coordination patterns differ as a function of vocalization type, whether different coordination patterns provide unique information about the dynamics of vocal interaction, and how the various coordination patterns each relate to infant age. All vocal coordination patterns displayed greater coordination for infant speech-related vocalizations, adults adapted the hierarchical clustering of their vocalizations to match that of infants, and each of the three coordination patterns had unique associations with infant age. Altogether, our results indicate that vocal coordination between infants and adults is multifaceted, suggesting a complex relationship between vocal coordination and the development of vocal communication.

Production and Convergence of Multiscale Clustering in Speech

Language entails the scaling of variability across levels of measurement—small linguistic variations occur at the millisecond level, larger variations occur at the next level, and even larger variations occur over longer timescales. For acoustic onsets in speech signals, small temporal variations occur at the phonetic level, larger variations occur at the phrasal level, and even larger variations occur at the conversational level. Scaling across levels of measurement can be quantified in terms of power law distributions. In this article we review recent investigations into power law clustering of acoustic speech onsets. Studies demonstrate that the multiscale clustering in onsets reflects communicative aspects of speech in adult conversations as well as infant vocalizations. We also review evidence that multiscale clustering in the vocalizations of individuals converges during vocal interactions. We relate multiscale convergence to the notion of complexity matching, that is, the hypothesis that maximal information transfer occurs when the power laws of 2 interacting complex systems are matched. We conclude by discussing potential extensions of this work including estimating the multifractal structure of speech and testing the maximal information transfer prediction of complexity matching.