Development of coordination in time estimation.

How to best characterize cognitive development? The claim put forward in this article is that development is the improvement of a kind of coordination among a variety of factors. To determine the development of coordination in a cognitive task, children between 4 and 12 years of age and adults participated in a time estimation task: They had to press a button every time they thought a short time interval had passed. The resulting data series of estimated time intervals was then subjected to a set of fractal analyses to quantify coordination in terms of its degree of "rigidity" (very highly integrated) vs. "looseness" (poorly integrated). Results show a developmental trajectory toward pink-noise patterns, suggesting that cognitive development progresses from a very loose, poorly integrated coordination of factors toward a pattern that expresses more integration, perhaps due to an optimization of constraints, that allows for a more stable coordination.

I know it when I quantify it: ecological momentary assessment and recurrence quantification analysis of emotion dysregulation in children with ADHD.

Two studies examined the feasibility, utility, and validity of Ecological Momentary Assessment (EMA) and Recurrence Quantification Analysis (RQA) in assessing emotion dysregulation in children with Attention-Deficit/Hyperactivity Disorder (ADHD). In Study 1, 11 parents of children with ADHD ages 8-11 completed EMA-based ratings of their children's mood three times daily for 28 days (84 ratings total) and questionnaires regarding their children's emotion dysregulation. RQA was used to quantify the temporal patterning of dysregulation of the children's mood. In Study 2, five children ages 8-11 completed EMA-based ratings of their mood three times daily for 28 days. Results supported the feasibility and validity of the parent report EMA protocol, with greater intensity, variability, and persistent patterning of variability associated with greater emotion dysregulation. Results did not support the validity of the child report protocol, as children were less likely to complete ratings when emotionally distressed and demonstrated substantial response bias.

Do Dyslexics Misread a ROWS for a ROSE?

Insufficient knowledge of the subtle relations between words' spellings and their phonology is widely held to be the primary limitation in developmental dyslexia. In the present study the influence of phonology on a semantic-based reading task was compared for groups of readers with and without dyslexia. As many studies have shown, skilled readers make phonology-based false-positive errors to homophones and pseudohomophones in the semantic categorization task. The basic finding was extended to children, teens, and adults with dyslexia from familial and clinically-referred samples. Dyslexics showed the same overall pattern of phonology errors and the results were consistent across dyslexia samples, across age groups, and across experimental conditions using word and nonword homophone foils. The dyslexic groups differed from chronological-age matched controls by having elevated false-positive homophone error rates overall, and weaker effects of baseword frequency. Children with dyslexia also made more false-positive errors to spelling control foils. These findings suggest that individuals with dyslexia make use of phonology when making semantic decisions both to word homophone and non-word pseudohomophone foils and that dyslexics lack adequate knowledge of actual word spellings, compared to chronological-age and reading-level matched control participants.

The blue-collar brain.

Much effort has gone into elucidating control of the body by the brain, less so the role of the body in controlling the brain. This essay develops the idea that the brain does a great deal of work in the service of behavior that is controlled by the body, a blue-collar role compared to the white-collar control exercised by the body. The argument that supports a blue-collar role for the brain is also consistent with recent discoveries clarifying the white-collar role of synergies across the body's tensegrity structure, and the evidence of critical phenomena in brain and behavior.

Feedback about isometric force production yields more random variations.

We investigated the relation between visual feedback and the degree of structure versus randomness in the variability of single-digit, isometric force output. Participants were instructed to maintain a constant level of force during the presence or absence of visual feedback about force output. The structure of force output variability was quantified using spectral analysis and detrended fluctuation analysis. Both analyses revealed that force output was less structured (more random) when visual feedback was available than when it was not. More random performance variation seemed to reflect a corrective strategy in the control of action.

Is cognitive science usefully cast as complexity science?

Readers of TopiCS are invited to join a debate about the utility of ideas and methods of complexity science. The topics of debate include empirical instances of qualitative change in cognitive activity and whether this empirical work demonstrates sufficiently the empirical flags of complexity. In addition, new phenomena discovered by complexity scientists, and motivated by complexity theory, call into question some basic assumptions of conventional cognitive science such as stable equilibria and homogeneous variance. The articles and commentaries that appear in this issue also illustrate a new debate style format for topiCS.

Pragmatic choice in conversation.

How do people decide what to say in context? Many theories of pragmatics assume that people have specialized knowledge that drives them to utter certain words in different situations. But these theories are mostly unable to explain both the regularity and variability in people's speech behaviors. Our purpose in this article is to advance a view of pragmatics based on complexity theory, which specifically explains the pragmatic choices speakers make in conversations. The concept of self-organized criticality sheds light on how a history of utterances and subtle details of a situation surrounding a conversation may directly specify language behavior. Under this view, pragmatic choice in discourse does not reflect the output of any dedicated pragmatic module but arises from a complex coordination or coupling between speakers and their varying communicative tasks.

Learning from the body about the mind.

In some areas of cognitive science we are confronted with ultrafast cognition, exquisite context sensitivity, and scale-free variation in measured cognitive activities. To move forward, we suggest a need to embrace this complexity, equipping cognitive science with tools and concepts used in the study of complex dynamical systems. The science of movement coordination has benefited already from this change, successfully circumventing analogous paradoxes by treating human activities as phenomena of self-organization. Therein, action and cognition are seen to be emergent in ultrafast symmetry breaking across the brain and body; exquisitely constituted of the otherwise trivial details of history, context, and environment; and exhibiting the characteristic scale-free signature of self-organization.

Does sample rate introduce an artifact in spectral analysis of continuous processes?

Spectral analysis is a widely used method to estimate 1/f(α) noise in behavioral and physiological data series. The aim of this paper is to achieve a more solid appreciation for the effects of periodic sampling on the outcomes of spectral analysis. It is shown that spectral analysis is biased by the choice of sample rate because denser sampling comes with lower amplitude fluctuations at the highest frequencies. Here we introduce an analytical strategy that compensates for this effect by focusing on a fixed amount, rather than a fixed percentage of the lowest frequencies in a power spectrum. Using this strategy, estimates of the degree of 1/f(α) noise become robust against sample rate conversion and more sensitive overall. Altogether, the present contribution may shed new light on known discrepancies in the psychological literature on 1/f(α) noise, and may provide a means to achieve a more solid framework for 1/f(α) noise in continuous processes.

Synchronized arousal between performers and related spectators in a fire-walking ritual.

Collective rituals are present in all known societies, but their function is a matter of long-standing debates. Field observations suggest that they may enhance social cohesion and that their effects are not limited to those actively performing but affect the audience as well. Here we show physiological effects of synchronized arousal in a Spanish fire-walking ritual, between active participants and related spectators, but not participants and other members of the audience. We assessed arousal by heart rate dynamics and applied nonlinear mathematical analysis to heart rate data obtained from 38 participants. We compared synchronized arousal between fire-walkers and spectators. For this comparison, we used recurrence quantification analysis on individual data and cross-recurrence quantification analysis on pairs of participants' data. These methods identified fine-grained commonalities of arousal during the 30-min ritual between fire-walkers and related spectators but not unrelated spectators. This indicates that the mediating mechanism may be informational, because participants and related observers had very different bodily behavior. This study demonstrates that a collective ritual may evoke synchronized arousal over time between active participants and bystanders. It links field observations to a physiological basis and offers a unique approach for the quantification of social effects on human physiology during real-world interactions.

Contemporary theories of 1/f noise in motor control.

1/f noise has been discovered in a number of time series collected in psychological and behavioral experiments. This ubiquitous phenomenon has been ignored for a long time and classical models were not designed for accounting for these long-range correlations. The aim of this paper is to present and discuss contrasted theoretical perspectives on 1/f noise, in order to provide a comprehensive overview of current debates in this domain. In a first part, we propose a formal definition of the phenomenon of 1/f noise, and we present some commonly used methods for measuring long-range correlations in time series. In a second part, we develop a theoretical position that considers 1/f noise as the hallmark of system complexity. From this point of view, 1/f noise emerges from the coordination of the many elements that compose the system. In a third part, we present a theoretical counterpoint suggesting that 1/f noise could emerge from localized sources within the system. In conclusion, we try to draw some lines of reasoning for going beyond the opposition between these two approaches.

Fractal 1/ƒ dynamics suggest entanglement of measurement and human performance.

Variability of repeated measurements in human performances exhibits fractal 1/ƒ noise. Yet the relative strength of this fractal pattern varies widely across conditions, tasks, and individuals. Four experiments illustrate how subtle details of the conditions of measurement change the fractal patterns observed across task conditions. The results call into question whether measurement noise and measured signal can be distinguished in human performance, suggesting that human performance is inextricably entangled with measurement context. Perhaps, though, a hypothesis of soft assembly of human performance can circumvent the conundrum (e.g., Turvey, 2007).

Situated naïve physics: task constraints decide what children know about density.

Children's understanding of density is riddled with misconceptions-or so it seems. Yet even preschoolers at times appear to understand density. This article seeks to reconcile these conflicting outcomes by investigating the nature of constraints available in different experimental protocols. Protocols that report misconceptions about density used stimulus arrangements that make differences in mass and volume more salient than differences in density. In contrast, protocols that report successful performance used stimulus arrangements that might have increased the salience of density. To test this hypothesis, the present experiments manipulate the salience of object density. Children between 2 and 9 years of age and adults responded whether an object would sink or float when placed in water. Results indicated that children's performance on exactly the same objects differed as a function of the saliency of the dimension of density, relative to the dimensions of mass and volume. These results support the idea that constraints--rather than stable knowledge--drive performance, with implications for teaching children about nonobvious concepts such as density.

Scaling laws in cognitive sciences.

Scaling laws are ubiquitous in nature, and they pervade neural, behavioral and linguistic activities. A scaling law suggests the existence of processes or patterns that are repeated across scales of analysis. Although the variables that express a scaling law can vary from one type of activity to the next, the recurrence of scaling laws across so many different systems has prompted a search for unifying principles. In biological systems, scaling laws can reflect adaptive processes of various types and are often linked to complex systems poised near critical points. The same is true for perception, memory, language and other cognitive phenomena. Findings of scaling laws in cognitive science are indicative of scaling invariance in cognitive mechanisms and multiplicative interactions among interdependent components of cognition.

Voluntary performance.

Will, purpose, and volition have long been viewed as either causes of behavior or of no direct consequence to behavior. In this essay, volition affects a flexible direct coupling of participant to task, modulating the degrees of freedom for kinematics in action, a point of view first introduced in theories of motor coordination. The consequence is an explanation consistent with present knowledge about involuntary and voluntary sources of control in human performance, and also the changes of the body expressed in aging and dynamical disease. Specifically, this view explains how tradeoffs between sources of overly regular versus overly random dynamics change the structure of variability in repeated measurements of voluntary performance.

Walking changes the dynamics of cognitive estimates of time intervals.

Cognitive performance exhibits patterns of trial-to-trial variation that can be described as 1/f or pink noise, as do repeated measures of locomotor performance. Although cognitive and locomotor performances are known to interact when performed concurrently, it is not known whether concurrent performance affects the tasks' pink noise dynamical structure. In this study, participants performed a cognitive task (repeatedly producing a temporal interval) and a motor task (walking on a treadmill) in single- and dual-task conditions. In single-task conditions both tasks exhibited pink noise structure. For concurrent performance the dynamical structure of the cognitive task changed reliably in the direction of white (random) noise. The dynamical structure of locomotion remained pink noise. The change in cognitive dynamics occurred despite no reliable changes in mean or standard deviation measures for either task. The results suggest a functional reorganization of cognitive dynamics supporting successful task performance in dual-task conditions.

Dispersion of response times reveals cognitive dynamics.

Trial-to-trial variation in word-pronunciation times exhibits 1/f scaling. One explanation is that human performances are consequent on multiplicative interactions among interdependent processes-interaction dominant dynamics. This article describes simulated distributions of pronunciation times in a further test for multiplicative interactions and interdependence. Individual participant distributions of approximately 1,100 word-pronunciation times were successfully mimicked for each participant in combinations of lognormal and power-law behavior. Successful hazard function simulations generalized these results to establish interaction dominant dynamics, in contrast with component dominant dynamics, as a likely mechanism for cognitive activity.

Soft-assembly of sensorimotor function.

Von Holst (1939/73) proposed relative coordination as a general characteristic of sensorimotor functions like locomotion. Its functionality derives from striking a balance between independence versus interdependence among component activities, e.g., fin or leg oscillations in lipfish and centipede models, respectively. A similar balancing act in the Ising (1925) model was found to produce patterns of electron spin alignment, analogous to the soft-assembly of locomotive patterns. The Ising model analog to relative coordination is metastability, and Kelso (1995) hypothesized that metastability is essential to sensorimotor functions across levels and domains of analysis, from individual neurons to neural systems to anatomical components of all kinds. In the present survey, relative coordination and metastability are hypothesized to underlie the soft-assembly of sensorimotor function, and this hypothesis is shown to predict 1/f scaling as a pervasive property of intrinsic fluctuations. Evidence is reviewed in support of this prediction from studies of human neural activity, as well as response time tasks and speech production tasks.

1/f scaling in movement time changes with practice in precision aiming.

When people perform repeated goal-directed movements, consecutive movement durations inevitably vary over trials, in poor as well as in skilled performances. The well-established paradigm of precision-aiming is taken as a methodological framework here. Evidence is provided that movement variability in closed tasks is not a random phenomenon, but rather shows a coherent temporal structure, referred to as 1/f scaling. The scaling relation appears more clearly as participants become trained in a highly constrained motor task. Also Recurrence Quantification Analysis (RQA) and Sample Entropy (SampEn) as analytic tools show that variation of movement times becomes less random and more patterned with motor learning. This suggests that motor learning can be regarded as an emergent, dynamical fusing of collaborating subsystems into a lower-dimensional organization. These results support the idea that 1/f scaling is ubiquitous throughout the cognitive system, and suggest that it plays a fundamental role in the coordination of cognitive as well as motor function.

The Pervasiveness of 1/f Scaling in Speech Reflects the Metastable Basis of Cognition.

Human neural and behavioral activities have been reported to exhibit fractal dynamics known as 1/f noise, which is more aptly named 1/f scaling. Some argue that 1/f scaling is a general and pervasive property of the dynamical substrate from which cognitive functions are formed. Others argue that it is an idiosyncratic property of domain-specific processes. An experiment was conducted to investigate whether 1/f scaling pervades the intrinsic fluctuations of a spoken word. Ten participants each repeated the word bucket over 1,000 times, and fluctuations in acoustic measurements across repetitions generally followed the 1/f scaling relation, including numerous parallel yet distinct series of 1/f fluctuations. On the basis of work showing that 1/f scaling is a universal earmark of metastability, it is proposed that the observed pervasiveness of 1/f fluctuations in speech reflects the fact that cognitive functions are formed as metastable patterns of activity in brain, body, and environment.