Symmetry axiom of Haken–Kelso–Bunz coordination dynamics revisited in the context of cognitive activity

We present an axiomatic derivation of a model proposed by Haken, Kelso, and Bunz (1985) that describes dynamical aspects of the rhythmic coordination between two limbs. Elaboration of this model has included a symmetry parameter that captures the coordination consequences of an inherent or imposed frequency difference between the limbs. We modified one of the axioms involved in the model derivation, a symmetry axiom, in order to incorporate a new symmetry parameter. This new parameter defines a shift between (a) the laboratory coordinate system, in which the behavior is observed, and (b) a second, postulated coordinate system. It is this second coordinate system, in which the relevant state dynamics is assumed to take place and in which the state dynamics evolves under the impact of an attractor. The state dynamics as described in the attractor coordinate system is then mapped by means of the new symmetry parameter to the laboratory coordinate system. We discuss analytically the bifurcation diagram of the model and determine main effects and interaction effects of manipulations related to the symmetry parameters and related to the mode of coordination (in-phase and anti-phase). The theoretical results are brought to bear on the challenging experimental observation that concurrent cognitive activity (counting, encoding, retrieving, sentence analysis) changes the location of the bimanual coordination attractor but not its strength. The theoretical results suggest that cognitive activity may have the effect it has because it shifts the attractor coordinate system relative to the laboratory coordinate system.     

Indiscriminate behavior observed in the strange situation among institutionalized toddlers: Relations to caregiver report and to early family risk

Socially disinhibited or indiscriminate behavior (IB) has traditionally been investigated using caregiver reports. More recently, an observational measure based on the Strange Situation Procedure (M. Ainsworth, M. Blehar, E. Waters, & S. Wall, 1978), the Rating of Infant and Stranger Engagement (RISE; C. Riley, A. Atlas‐Corbett, & K. Lyons‐Ruth, 2005), was validated in home‐reared at‐risk children. The present study aimed to validate the RISE in an institutionally reared sample using the caregiver report, to assess whether IB assessed with the RISE was elevated among the institutionalized children, and to explore potential risk factors associated with IB. The study was conducted among 74 institutionalized toddlers aged 11 to 30 months. Sociodemographic questionnaires were used to assess pre‐admission experiences, and aspects of institutional placement were coded from the children's files in the institution and staff's report. Institutionalized children displayed high frequencies of IB as assessed on the RISE, and this instrument was validated against caregiver report. Pre‐admission experiences of the institutionalized children in their biological families—namely, prenatal risk and maternal emotional neglect risk—predicted IB. Results suggest that the RISE is adequate to use among institutionally reared toddlers and point to aspects of the early familial environment that may be implicated in IB.     

Asymmetric switch-costs and ERPs reveal facial identity dominance over expression

Previous studies on face processing have revealed an asymmetric overlap between identity and expression, as identity is processed irrespective of expression while expression processing partly depends on identity. To investigate whether this relative interaction is caused by dominance of identity over expression, participants performed familiarity and expression judgments during task switching. This paradigm reveals task-set dominance with a paradoxical asymmetric switch-cost (i.e., greater difference between switch and repeat trials when switching toward the dominant task). Event-related potentials (ERPs) were recorded to find the neural signature of the asymmetric cost. As expected, greater switch-cost was shown in the familiarity task with respect to response times, indicating its dominance over the expression task. Moreover, a left-sided ERP correlate of this effect was observed at the level of the frontal N2 component, interpreted as an index of modulations in endogenous executive control. Altogether, these results confirm the overlap between identity and expression during face processing and further indicate their relative dominance.     

Transitional and steady-state choice behavior under an adjusting-delay schedule

Twelve rats made repeated choices on an adjusting-delay schedule between a smaller reinforcer (A) that was delivered immediately after a response and a larger reinforcer (B) that was delivered after a delay which increased or decreased by 20% depending on the subject's choices in successive blocks of trials. In two phases of the experiment (100 sessions and 40 sessions), reinforcer sizes were selected which enabled theoretical parameters expressing the rate of delay discounting and sensitivity to reinforcer size to be estimated from the ratio of the indifference delays obtained in the two phases. Indifference delays, calculated from adjusting delays in the last 10 sessions of each phase, were shorter when the sizes of A and B were 14 and 25 μl of a 0.6 M sucrose solution than when they were 25 and 100 μl of the same solution. The ratio of the indifference delays was significantly smaller than that predicted on the basis of an assumed linear relation between reinforcer size and instantaneous reinforcer value, consistent with a previous proposal that this relation may be hyperbolic in form. Estimates of the rate of delay discounting based on the ratio of the two indifference delays (mean, 0.08 s(-1)) were similar to values obtained previously using different intertemporal choice protocols. Estimates of the size-sensitivity parameter (mean 113 μl) were similar to estimates recently derived from performance on progressive-ratio schedules. In both phases of the experiment, adjusting delays in successive blocks of trials were analyzed using the Fourier transform. The power spectrum obtained from individual rats had a dominant frequency that corresponded to a period of oscillation of the adjusting delay between 30 and 100 trial blocks (mean, 78). Power in the dominant frequency band was highest in the early sessions of the first phase and declined with extended training. It is suggested that this experimental protocol may have utility in neurobehavioral studies of intertemporal choice.     

Parental Marital Discord and Treatment Response in Depressed Adolescents

Evidence suggests that parental marital discord contributes to the development of internalizing and externalizing symptoms in children and adolescents. Few studies, however, have examined the association between parental marital discord and youth’s response to treatment. The present study examined the impact of interparental discord on treatment response in a randomized control trial of adolescents with major depression enrolled in the Treatment for Adolescents with Depression Study (TADS). Participants were 260 adolescents from two-parent households randomly assigned to one of four treatment groups: fluoxetine (FLX), cognitive behavior therapy (CBT), their combination (COMB), or placebo (PBO). Logistic regressions revealed that parental marital discord interacted with youth gender and co-morbid oppositionality symptoms to predict group differences in treatment response.     

Neuro-cognitive mechanisms of decision making in joint action: a human-robot interaction study

In this paper we present a model for action preparation and decision making in cooperative tasks that is inspired by recent experimental findings about the neuro-cognitive mechanisms supporting joint action in humans. It implements the coordination of actions and goals among the partners as a dynamic process that integrates contextual cues, shared task knowledge and predicted outcome of others’ motor behavior. The control architecture is formalized by a system of coupled dynamic neural fields representing a distributed network of local but connected neural populations. Different pools of neurons encode task-relevant information about action means, task goals and context in the form of self-sustained activation patterns. These patterns are triggered by input from connected populations and evolve continuously in time under the influence of recurrent interactions. The dynamic model of joint action is evaluated in a task in which a robot and a human jointly construct a toy object. We show that the highly context sensitive mapping from action observation onto appropriate complementary actions allows coping with dynamically changing joint action situations.     

Cognitive abilities, sociocultural background and academic achievement

The influence of students' sociocultural background on academic achievement is a well established fact. Research also points out that sociocultural background is related to students' cognitive abilities and these have an effect on their academic achievement. However, the mediator role of cognitive abilities on the relationship between sociocultural background and academic achievement is less well known. A structural equation model that represents these relationships was tested in a sample (N= 728) of Portuguese junior high school students. Multigroup analysis of the model showed the importance of the cognitive ability mediation effect between sociocultural background and academic achievement in the 7th and 9th grades, but not in the 8th grade. This difference may be the result of the academic transition experienced in the 7th and 9th grades in the Portuguese educational system, which requires parents' higher involvement in school.     

Psychological variables in the control of brain-computer interfaces

BCI (Brain-Computer Interface) is a system that allows interaction between the human brain and a computer. It is based on analyzing electroencephalographic signals (EEG) and processing them to generate control commands. The study analyzed the possible influence of psychological variables, such as the imaginative kinesthetic capacity and anxiety, in relation to performance in a BCI. All participants (4 male and 19 female students) completed the questionnaires and carried out a session of BCI to control their EEG signals in a virtual setting of a car along a straight road. The group was divided into two subgroups according to their EEG signals or differential responses obtained in the left-right discrimination. Study results showed no significant differences in cognitive variables of imagination or in anxiety. By comparing the degree of participants' BCI control, a new quantitative parameter for comparing performances and making decisions in signal processing was found. The findings, the ongoing research process to refine the control of a BCI, and the interaction of psychological and computer procedures are discussed.