Empirical Evidence for Extended Cognitive Systems

We present an empirically supported theoretical and methodological framework for quantifying the system-level properties of person-plus-tool interactions in order to answer the question: “Are person-plus-tool-systems extended cognitive systems?” Nineteen participants provided perceptual judgments regarding their ability to pass through apertures of various widths while using visual information, blindfolded wielding a rod, or blindfolded wielding an Enactive Torch—a vibrotactile sensory-substitution device for detecting distance. Monofractal, multifractal, and recurrence quantification analyses were conducted to assess features of person-plus-tool movement dynamics. Trials where people utilized the rod or Enactive Torch demonstrated stable “self-similarity,” or indices of healthy and adaptive single systems, regardless of aperture width, trial order, features of the participants’ judgments, and participant characteristics. Enactive Torch trials exhibited a somewhat greater range of dynamic fluctuations than the rod trials, as well as less movement recurrence, suggesting that the Enactive Torch allowed for more exploratory movements. Findings provide support for the notion that person-plus-tool systems can be classified as extended cognitive systems and a framework for quantifying system-level properties of these systems. Implications concerning future research on extended cognition are discussed.     

Effects of sensory manipulations on the dynamical structure of center-of-pressure trajectories of children with cerebral palsy during sitting

Aim: To investigate the effects of manipulating visual information and the compliance of the support surface on the area of sway and dynamical trajectories of center-of-pressure (CoP) in children with CP and children with typical development during static sitting. Methods: 32 typical children, 14 children with mild CP and 12 with moderate-to-severe CP were tested for CoP sway during static sitting under four sensory conditions: (1) eyes open on a rigid surface; (2) eyes closed on a rigid surface; (3) eyes open on foam; (4) eyes closed on foam. Results: Children with moderate-to-severe CP showed greater regularity and local stability of dynamical CoP trajectories and lower complexity in their motor patterns than typical children and children with mild CP. Moreover, removing vision and sitting on a compliant surface reduced the regularity of CoP trajectories. Conclusion: Children with CP were able to adjust the structure and complexity of their postural control responses to sensory challenges, although the structure of their postural responses was poorer than in typical children.     

Preliminary evidence of diurnal rhythms in everyday behaviors associated with positive affect

The authors used the Electronically Activated Recorder (EAR) to track within-day variability in everyday behaviors associated with positive and negative affect across two samples. The EAR is a portable audio recorder that periodically samples snippets of ambient sounds from participants’ momentary environments. The recorded sounds are then coded for different behaviors. The study tested whether previous findings regarding diurnal patterns in self-reported mood extend to naturalistically observed behavior. Across both samples, behavior associated with positive affect (i.e., socializing, laughing, and singing) varied according to a sinusoidal 24-h rhythm centered around participants’ average waketime while behavior associated with negative affect (i.e., arguing and sighing) did not. Further, there was preliminary evidence that personality traits can moderate these rhythms (e.g., their amplitude).     

Mixed effects modeling of Morris water maze data: Advantages and cautionary notes

Morris water maze data are most commonly analyzed using repeated measures analysis of variance in which daily test sessions are analyzed as an unordered categorical variable. This approach, however, may lack power, relies heavily on post hoc tests of daily performance that can complicate interpretation, and does not target the nonlinear trends evidenced in learning data. The present project used Monte Carlo simulation to compare the relative strengths of the traditional approach with both linear and nonlinear mixed effects modeling that identifies the learning function for each animal and condition. Both trend-based mixed effects modeling approaches showed much greater sensitivity to identifying real effects, and the nonlinear approach provided uniformly better fits of learning trends. The common practice of removing a rat from the maze after 90 s, however, proved more problematic for the nonlinear approach and produced an underestimate of y-axis intercepts.     

Perceived self-efficacy by Under-10 tennis players when scaling the equipment and play area

The modification of child-sports aims to develop an optimal learning environment that facilitates the emergence of desirable psychological outcomes (e.g., self-efficacy). The aim of the study was to assess the effect of reducing net height and court size on self-efficacy and shot-efficacy of U-10 tennis players in a real-game context. Twenty U-10 tennis players (M = 9.46, SD = 0.66 years of age; M = 3.65, SD = 1.53 years of tennis experience) played two round-robin tournaments one week apart in the same order and schedule. The first tournament was played under the International Tennis Federation’s Tennis 10s regulation at green stage (GT). Afterwards, the modified tournament (MT) was played with the same regulation GT, however, net height (0.91 m–0.80 m) and court size (23.77 m × 8.23 m–18.00 m × 8.23 m) were reduced. Results accomplished using Bayesian and Frequentist inferences showed an increase in players’ self-efficacy when serving in MT than GT (BF₁₀ = 4.796; δ = −0.576; and p = .011). This is increase may be due to a reduction in their serving faults in MT (BF₁₀ = 6.169; δ = −0.591; and p = .010). Therefore, reducing net height and court size enhances the serve performance and self-efficacy and thus promotes positive tennis experiences.     

Beyond Dyadic Coordination: Multimodal Behavioral Irregularity in Triads Predicts Facets of Collaborative Problem Solving

We hypothesize that effective collaboration is facilitated when individuals and environmental components form a synergy where they work together and regulate one another to produce stable patterns of behavior, or regularity, as well as adaptively reorganize to form new behaviors, or irregularity. We tested this hypothesis in a study with 32 triads who collaboratively solved a challenging visual computer programming task for 20 min following an introductory warm‐up phase. Multidimensional recurrence quantification analysis was used to examine fine‐grained (i.e., every 10 s) collective patterns of regularity across team members' speech rate, body movement, and team interaction with the shared user interface. We found that teams exhibited significant patterns of regularity as compared to shuffled baselines, but there were no systematic trends in regularity across time. We also found that periods of regularity were associated with a reduction in overall behavior. Notably, the production of irregular behavior predicted expert‐coded metrics of collaborative activity, such as teams' ability to construct shared knowledge and effectively negotiate and coordinate execution of solutions, net of overall behavioral production and behavioral self‐similarity. Our findings support the theory that groups can interact to form interpersonal synergies and indicate that information about system‐level dynamics is a viable way to understand and predict effective collaborative processes.     

Symmetry breaking analysis of prism adaptation's latent aftereffect

The effect of prism adaptation on movement is typically reduced when the movement at test (prisms off) differs on some dimension from the movement at training (prisms on). Some adaptation is latent, however, and only revealed through further testing in which the movement at training is fully reinstated. Applying a nonlinear attractor dynamic model (Frank, Blau, & Turvey, 2009) to available data (Blau, Stephen, Carello, & Turvey, 2009), we provide evidence for a causal link between the latent (or secondary) aftereffect and an additive force term that is known to account for symmetry breaking. The evidence is discussed in respect to the hypothesis that recalibration aftereffects reflect memory principles (encoding specificity, transfer-appropriate processing) oriented to time-translation invariance-when later testing conserves the conditions of earlier training. Forgetting or reduced adaptation effects follow from the loss of this invariance and are reversed by its reinstatement.     

Local dynamic stability of the spine and its coordinated lower joints during repetitive Lifting: Effects of fatigue and chronic low back pain

The nonlinear Lyapunov exponent (LyE) has been proven effective for evaluating the local stability of human movement and exploring the effects of load, speed and direction of individuals with and without nonspecific chronic low back pain (CLBP). The purpose of this study was to examine spinal and lower joint stability and response to fatigue of individuals with and without CLBP while performing lifting-lowering movements. Fourteen healthy individuals and 14 patients with nonspecific CLBP were recruited to perform lifting movement repeatedly while holding two equally-sized dumbbells in their hands. The participants continued lifting until they reported their highest level of fatigue. Kinematic data for the spine and its coordinated lower joints were recorded during the task (more than 40 lifting cycles on average). The first and last 20 cycles of each cyclic time series were defined as early- and late-fatigue conditions, respectively. The maximum LyE was estimated to quantify the local dynamic stability of the angular displacement time series of the spine, hip, knee and ankle on different anatomical planes in both the early- and late-fatigue conditions. The results revealed that local stability of the spine and hip was affected by fatigue. Spinal stability decreased as fatigue increased on the sagittal plane (p < 0.05). The hip exhibited a similar affectation (destabilization under fatigue) on all anatomical planes. Patients with CLBP showed more stable hip movement on the frontal and transverse planes (p < 0.05). These results suggested that lifting/progressive fatigue could increase the risk of injury to the spine and hip. These findings indicate that patients with CLBP applied different control strategies for the hip; thus, spinal control stability should be evaluated together with the stability of the lower joints.     

Downward causation in fluid convection

Recent developments in nonlinear dynamics have found wide application in many areas of science from physics to neuroscience. Nonlinear phenomena such as feedback loops, inter-level relations, wholes constraining and modifying the behavior of their parts, and memory effects are interesting candidates for emergence and downward causation. Rayleigh–Bénard convection is an example of a nonlinear system that, I suggest, yields important insights for metaphysics and philosophy of science. In this paper I propose convection as a model for downward causation in classical mechanics, far more robust and less speculative than the examples typically provided in the philosophy of mind literature. Although the physics of Rayleigh–Bénard convection is quite complicated, this model provides a much more realistic and concrete example for examining various assumptions and arguments found in emergence and philosophy of mind debates. After reviewing some key concepts of nonlinear dynamics, complex systems and the basic physics of Rayleigh–Bénard convection, I begin that examination here by (1) assessing a recently proposed definition for emergence and downward causation, (2) discussing some typical objections to downward causation and (3) comparing this model with Sperry’s examples. The aim of science is not things themselves, as the dogmatists in their simplicity imagine, but the relations among things; outside these relations there is no reality knowable. – Poincaré     

Dynamics of phonological cognition

A fundamental problem in spoken language is the duality between the continuous aspects of phonetic performance and the discrete aspects of phonological competence. We study 2 instances of this problem from the phenomenon of voicing neutralization and vowel harmony. In each case, we present a model where the experimentally observed continuous distinctions are linked to the discreteness of phonological form using the mathematics of nonlinear dynamics.