The emergent coordination of cognitive function

1/f scaling has been observed throughout human physiology and behavior, but its origins and meaning remain a matter of debate. Some argue that it is a byproduct of ongoing processes in the brain or body and therefore of limited relevance to psychological theory. Others argue that 1/f scaling reflects a fundamental aspect of all physiological and cognitive functions, namely, that they emerge in the balance of independent versus interdependent component activities. In 4 experiments, series of key-press responses were used to test between these 2 alternative explanations. The critical design feature was to take 2 measures of each key-press response: reaction time and key-contact duration. These measures resulted in 2 parallel series of intrinsic fluctuations for each series of key-press responses. Intrinsic fluctuations exhibited 1/f scaling in both reaction times and key-contact durations, yet the 2 measures were uncorrelated with each other and separately perturbable. These and other findings indicate that 1/f scaling is too pervasive to be idiosyncratic and of limited relevance. It is instead argued that 1/f scaling reflects the coordinative, metastable basis of cognitive function.     

Disequilibrium in the mind, disharmony in the body

Although it is generally acknowledged that experiences of frustration, confusion, and anxiety are embodied phenomena, very little is known about how these processes modulate presumably unconscious, but constantly present, subtle bodily movement. We addressed this problem by tracking the low-level dynamics of body movement, using 1/f noise, pink noise, or "fractal scaling", during naturalistic experiences of affect in two studies involving deep learning and effortful problem-solving. Our results indicate that body movement fluctuations of individuals experiencing cognitive equilibrium was characteristic of correlated pink noise, but there was a whitening of the signal when participants experienced states that are diagnostic of cognitive distress such as anxiety, confusion, and frustration. We orient our findings within theories that emphasise the embodied nature of cognition and affect and with perspectives that view affective and cognitive processes as emergent products of a self-organising dynamical system (the brain) that is inextricably coupled to the body.     

1/f noise in human cognition: Is it ubiquitous, and what does it mean?

Researchers in psychology are paying increasing attention to temporal correlations in performance on cognitive tasks. Recently, Thornton and Gilden (2005) introduced a spectral method for analyzing psychological time series; in particular, this method is tailored to distinguish transient serial correlations from the persistent correlations characterized by 1/f noise. Thornton and Gilden applied their method to word-naming data to support the claimed ubiquity of 1/f noise in psychological time series. We argue that a previously presented method for distinguishing transient and persistent correlations (e.g., Wagenmakers, Farrell, & Ratcliff, 2004) compares favorably with the new method presented by Thornton and Gilden. We apply Thornton and Gilden’s method to time series from a range of cognitive tasks and show that 1/f noise is not a ubiquitous property of psychological time series. Finally, we assess the theoretical developments in this area and argue that the development of well-specified models of the principles or mechanisms of human cognition giving rise to 1/f noise is long overdue.     

Response-time dynamics: Evidence for linear and low-dimensional nonlinear structure in human choice sequences

Response time (RT) is a commonly used measure of cognitive performance, which is usually characterized as stochastic. However, useful information may be hidden in the apparently random fluctuations of RT. Dynamical systems analysis techniques allow an exploration of the alternative hypothesis that RT fluctuations are deterministic, albeit in a complex manner. We applied careful task construction and noise-reduction and surrogate series tests to show that RT series from a forced-pace serial response-time task have low-dimensional chaotic characteristics. In Experiment 1, 80% of subjects' filtered RT series had low dimensionality, sensitive dependence on initial conditions, spectra close to 1/ f , and stable attractor geometry across sessions. In Experiment 2, we showed that the size of the inter-stimulus interval (ISI) determined the number of subjects with low-dimensional chaotic series. A small ISI caused 100% of subjects to respond in the chaotic regime, whereas only 25% had a low-dimensional chaotic RT component when the ISI was large. We argue that demanding task requirements cause a reduction in the dimensionality of the dynamics, producing RT fluctuations that may reflect a response strategy for controlling RT.     

Interdependence of Saccadic and Fixational Fluctuations

Recent research suggests that the different components of eye movements (fixations, saccades) are not strictly separate but are interdependent processes. This argument rests on observations that gaze-step sizes yield unimodal distributions and exhibit power-law scaling, indicative of interdependent processes coordinated across timescales. The studies that produced these findings, however, employed complex tasks (visual search, scene perception). Thus, the question is whether the observed interdependence is a fundamental property of eye movements or emerges in the interplay between cognitive processes and complex visual stimuli. In this study, we used a simple eye movement task where participants moved their eyes in a prescribed sequence at several different paces. We outlined diverging predictions for this task for independence versus interdependence of fixational and saccadic fluctuations and tested these predictions by assessing the spectral properties of eye movements. We found no clear peak in the power spectrum attributable exclusively to saccadic fluctuations. Furthermore, changing the pace of the eye movement sequence yielded a global shift in scaling relations evident in the power spectrum, not just a localized shift for saccadic fluctuations. These results support the conclusion that fixations and saccades are interdependent processes.     

Disequilibrium in the mind,disharmony in the body

Although it is generally acknowledged that experiences of frustration, confusion, and anxiety are embodied phenomena, very little is known about how these processes modulate presumably unconscious, but constantly present, subtle bodily movement. We addressed this problem by tracking the low-level dynamics of body movement, using 1/f noise, pink noise, or “fractal scaling”, during naturalistic experiences of affect in two studies involving deep learning and effortful problem-solving. Our results indicate that body movement fluctuations of individuals experiencing cognitive equilibrium was characteristic of correlated pink noise, but there was a whitening of the signal when participants experienced states that are diagnostic of cognitive distress such as anxiety, confusion, and frustration. We orient our findings within theories that emphasise the embodied nature of cognition and affect and with perspectives that view affective and cognitive processes as emergent products of a self-organising dynamical system (the brain) that is inextricably coupled to the body.     

Directions in Connectionist Research: Tractable Computations Without Syntactically Structured Representations

Should connectionists abandon the quest for tractably computable cognitive transition functions while retaining syntactically structured mental representations? We argue, in opposition to Horgan, that it should not. We argue that the case against tractably computable functions, based upon the claimed isotropic and Quinean character of cognition, fails since cognition is not as isotropic and Quinean as Fodor and Horgan contend. Moreover, we illustrate how current research in both connectionism and cognitive neuroscience suggests that tractability can be preserved through division of overall computations into modular sub-processes, each of which is tractable. As to syntactically structured representations, we argue that they are unneeded for most cognitive tasks organisms confront, and that when they are needed, they may be provided by external representational media such as natural language. Moreover, we note that increasingly cognitive linguistics has become the ally of connectionism and that the research program of cognitive linguistics suggests that abilities to use natural languages may be developed without requiring syntactically structured mental representations to exist prior to natural language.     

Tricks of Memory

Remembering an episode from even the recent past may involve a blend of fiction and fact. We discuss a straight-forward laboratory paradigm that is proving useful in the study of false memories of simple episodes. In this paradigm, subjects study lists of 15 related words ( bed, rest, awake ...) that are all related to a critical word that is not presented ( sleep ). Later, subjects recall and recognize the critical missing word with about the same probability that they remember words from the list. This memory illusion is resistant to people's attempts to avoid it. We argue that similar memory errors are commonplace and are a natural outcome of an intelligent cognitive system, which makes inferences about incoming information. Therefore, memory illusions, like perceptual illusions, are a consequence of normal human information processing and offer a window for examining basic cognitive processes.     

Cognitive emissions of 1/f noise

The residual fluctuations that naturally arise in experimental inquiry are analyzed in terms of their time histories. Although these fluctuations are generally relegated to a statistical purgatory known as unexplained variance, this article shows that they may harbor a long-term memory process known as 1/f noise. This type of noise has been encountered in a number of biological and physical systems and is theorized to be a signature of dynamic complexity. Its presence in psychological data appears to be associated with the most elementary aspect of cognitive process, the formation of representations.     

The curious case of spillover: Does it tell us much about saccade timing in reading?

In completing daily activities, the eyes make a series of saccades by gazing at stimuli in succession. The duration of gaze on each stimulus has been used to infer how the initiation of a saccade is timed relative to the underlying mental processing. In reading, gaze dwells longer on a word that occurs infrequently in English text (low frequency) than on a more frequent word (high frequency), but also on the following word, which is referred to as spillover. Accounts of spillover attribute it to mechanisms of lexical access. A low-frequency word n is assumed to delay the onset of cognitive processing of word n+1 more than it delays the saccade to n+1, leaving more processing to be done on n+1 once it is fixated. We tested this assumption by having participants perform a series of speeded lexical decisions on a linear array of letter strings spaced 5° apart, using low- and high-frequency words to vary the lexical difficulty. Lexical decision adds a response selection stage that is absent in reading, which should eliminate differential effects on saccades and cognitive processing. Nonetheless, we found the typical pattern of lengthened gaze duration and spillover for low-frequency words, with effects that were consistent in magnitude with those seen in studies of reading. These data challenge existing accounts of spillover and argue against the idea that reading has a unique interaction with oculomotor control. Instead, the similarity of our gaze patterns to those of reading suggests a common pattern of saccade initiation across tasks.     

Beyond naïve cue combination: salience and social cues in early word learning

Children learn their earliest words through social interaction, but it is unknown how much they rely on social information. Some theories argue that word learning is fundamentally social from its outset, with even the youngest infants understanding intentions and using them to infer a social partner's target of reference. In contrast, other theories argue that early word learning is largely a perceptual process in which young children map words onto salient objects. One way of unifying these accounts is to model word learning as weighted cue combination, in which children attend to many potential cues to reference, but only gradually learn the correct weight to assign each cue. We tested four predictions of this kind of naïve cue combination account, using an eye‐tracking paradigm that combines social word teaching and two‐alternative forced‐choice testing. None of the predictions were supported. We thus propose an alternative unifying account: children are sensitive to social information early, but their ability to gather and deploy this information is constrained by domain‐general cognitive processes. Developmental changes in children's use of social cues emerge not from learning the predictive power of social cues, but from the gradual development of attention, memory, and speed of information processing.     

Visual cerebral lateralization over phases of the menstrual cycle: a preliminary investigation

This study investigated whether visual cerebral asymmetries would change in phase with hormonal variations during the menstrual cycle. Lexical decision and line orientation tasks were administered during follicular, luteal, and menstrual phases of each woman's cycle. These tasks were also administered to a reference group of male subjects. Signal detection analyses indicated an unvarying RVF advantage in word/nonword discriminability (d') throughout the menstrual cycle, but a phase-dependent shift in left hemisphere response criterion (log beta). Gender differences were present for discriminability of line orientation, and female performance on this task varied over the cycle. The results imply that the neural systems subserving some cognitive functions are sensitive to fluctuations in gonadal steroids and suggest a hormonal basis for gender differences in some visual-spatial functions.     

The role of prevention focus under stereotype threat: Initial cognitive mobilization is followed by depletion

Previous research has demonstrated that stereotype threat induces a prevention focus and impairs central executive functions. The present research examines how these 2 consequences of stereotype threat are related. The authors argue that the prevention focus is responsible for the effects of stereotype threat on executive functions and cognitive performance. However, because the prevention focus is adapted to deal with threatening situations, the authors propose that it also leads to some beneficial responses to stereotype threat. Specifically, because stereotype threat signals a high risk of failure, a prevention focus initiates immediate recruitment of cognitive control resources. The authors further argue that this response initially facilitates cognitive performance but that the additional cognitive demands associated with working under threat lead to cognitive depletion over time. Study 1 demonstrates that stereotype threat (vs. control) facilitates immediate cognitive control capacity during a stereotype-relevant task. Study 2 experimentally demonstrates the process by showing that stereotype threat (vs. control) facilitates cognitive control as a default, as well as when a prevention focus has been experimentally induced, but not when a promotion focus has been induced. Study 3 shows that stereotype threat facilitates initial math performance under a prevention focus, whereas no effect is found under a promotion focus. Consistent with previous research, however, stereotype threat impaired math performance over time under a prevention focus, but not under a promotion focus.     

新词词素熟悉性影响视觉词切分线索在新词学习中的促进作用

为考察词素熟悉性是否会影响视觉词切分线索在新词学习中的作用,本研究中新词由两类假词构成：第一类假词由两个高频字（高熟悉性词素）组成,第二类假词由两个低频字（低熟悉性词素）组成。实验采用学习-测试范式,将新词镶嵌在句子中供大学生被试阅读。结果发现,相比由低熟悉性词素构成的新词,词间空格在由高熟悉词素构成的新词中起到的促进作用更大。表明在汉语阅读过程中,词素熟悉性可能作为一种线索参与词切分。     

Is the heart preadapted to hypoxia? Evidence from fractal dynamics of heartbeat interval fluctuations at high altitude (5,050 m)

The dynamics of heartbeat interval time series over large time scales were studied by a modifed random walk analysis introduced recently asDetrended Fluctuation Analysis. In this analysis, the intrinsic fractal long-range power-law correlation properties of beat-to-beat fluctuations generated by the dynamical system (i.e., cardiac rhythm generator), after decomposition from extrinsic uncorrelated sources, can be quantified by the scaling exponent (α) which, in healthy subjects, for time scales of ∼10⁴ beats is ∼1.0. The effects of chronic hypoxia were determined from serial heartbeat interval time series of digitized twenty-four-hour ambulatory ECGs recorded in nine healthy subjects (mean age thirty-four years old) at sea level and during a sojourn at 5,050 m for thirty-four days (Ev-K2-CNR Pyramid Laboratory, Sagarmatha National Park, Nepal). The group averaged α exponent (±SD) was 0.99±0.04 (range 0.93–1.04). Longitudinal assessment of α in individual subjects did not reveal any effect of exposure to chronic high altitude hypoxia. The finding of α∼1 indicating scale-invariant long-range power-law correlations (1/f noise) of heartbeat fluctuations would reflect a genuinely self-similar fractal process that typically generates fluctuations on a wide range of time scales. Lack of a characteristic time scale along with the absence of any effect from exposure to chronic hypoxia on scaling properties suggests that the neuroautonomic cardiac control system is preadapted to hypoxia which helps prevent excessive mode-locking (error tolerance) that would restrict its functional responsiveness (plasticity) to hypoxic or other physiological stimuli. Editorial Note: A philosopher is, by definition, a lover of wisdom. In the following article, Dr. Dimitrov, as a philosopher, examines the principles that underlie being and thinking as performed by the structures of the brain. He reports his thoughts in a “virtual context.” Virtual, a word enjoying great popularity today, is derived from the Latin word for man; it describes manliness and implies apparent, but not actual, power. In his analysis of how information is dealt with by the human being, the author uses theoretical physics and mathematics that may seem arcane to some readers. A major aspect of his thesis declares that the effective performance of information systems relies not on the structures involved, but on the way they interact.     

BASIC RELATIONS IN CHILD LANGUAGE AND THE WORD ORDER MYTH

The research involved an evaluation of the psychological reality of the syntactic functions of subject and object, the semantic functions of agent and patient, and the discourse functions of given and new. The domain of analysis was from the early two-word into the early three-word phase (approximately 1;7 to 2;5) of the acquisition of the relatively synthetic language of Polish. An analysis of the inflectional morphology revealed the appropriate use of all seven cases and contrasts within three dimensions of agreement before 1;9. These varied inflectional forms were used with sufficient frequency to argue that the nominative case and the agreement relations are productive subjecthood properties at this phase of development. The semantic function of the subject noun phrase was either an agent or a patient. Hence, case and agreement cannot be reduced to properties of semantic functions. Since both subject and object were rarely realized simultaneously in the surface structure in the early phase of two word utterances, the set of verb plus subject and verb plus object patterns (i.e., SV, VS, OV, and VO) were analyzed for the discourse functions of given and new. Neither discourse function nor cannonical (SV and VO) form control word order. As both subject and object came to be realized in the surface structure, subject before object priority was revealed as a subjecthood property but not in a rigid word order (i.e., both SVO and SOV patterns occurred). The evidence demonstrates the independent status of the syntactic function of subject.     

Self-organization of cognitive performance

Background noise is the irregular variation across repeated measurements of human performance. Background noise remains after task and treatment effects are minimized. Background noise refers to intrinsic sources of variability, the intrinsic dynamics of mind and body, and the internal workings of a living being. Two experiments demonstrate 1/f scaling (pink noise) in simple reaction times and speeded word naming times, which round out a catalog of laboratory task demonstrations that background noise is pink noise. Ubiquitous pink noise suggests processes of mind and body that change each other's dynamics. Such interaction-dominant dynamics are found in systems that self-organize their behavior. Self-organization provides an unconventional perspective on cognition, but this perspective closely parallels a contemporary interdisciplinary view of living systems.     

汉字位置加工和词边界效应的认知机制

在中文阅读中, 为了进行词汇识别, 需要对汉字在词中的相对顺序进行加工, 即汉字位置加工。汉字位置加工是词汇识别和阅读理解的重要环节。如果汉字位置未得到加工, 可转置词将很难被区分。可转置词由相同汉字构成, 但每个汉字所处位置不同。以往研究发现, 词内汉字位置加工是比较灵活的; 而且词边界信息会影响汉字位置的加工, 即汉字位置加工存在词边界效应。该效应产生的原因及影响因素有哪些?本项目采用眼动追踪技术, 在自然阅读中系统探讨如下三个问题:(1)词的首/尾汉字如何调节汉字位置加工过程; (2)嵌套词和歧义词边界如何影响汉字位置加工; (3)语境合理性和预测性如何影响汉字位置加工的词边界效应。本项目将为首个中文汉字位置加工模型的建立提供数据支持和科学基础, 推进现有的中文词汇识别和词切分模型的进一步完善, 并为词汇的高效率教授与学习提供科学指导。     

What Am I? Virtual Machines and the Mind/Body Problem

When your word processor or email program is running on your computer, this creates a “virtual machine” that manipulates windows, files, text, etc. What is this virtual machine, and what are the virtual objects it manipulates? Many standard arguments in the philosophy of mind have exact analogues for virtual machines and virtual objects, but we do not want to draw the wild metaphysical conclusions that have sometimes tempted philosophers in the philosophy of mind. A computer file is not made of epiphenomenal ectoplasm. I argue instead that virtual objects are “supervenient objects.” The stereotypical example of supervenient objects is the statue and the lump of clay. To this end I propose a theory of supervenient objects. Then I turn to persons and mental states. I argue that my mental states are virtual states of a cognitive virtual machine implemented on my body, and a person is a supervenient object supervening on this cognitive virtual machine.