Nonlinearity in the Epidemiology of Complex Health and Disease Processes

Theoretical Medicine and Bioethics - The challenges posed by chronic illness have pointed out to epidemiologists the multifactorial complex nature of disease causality. This notion has been...     

Effect of Stroke on Joint Control during Reach-to-Grasp: A Preliminary Study

Abstract

We investigated changes in control of inter-segmental dynamics underlying upper extremity dyscoordination caused by stroke. Individuals with stroke and healthy individuals performed a natural reach-to-grasp movement. Kinetic analysis revealed that both groups rotated the shoulder by muscle torque and used interaction torque to rotate the elbow. However, individuals with stroke used interaction torque less than healthy individuals, actively suppressing a substantial portion of it. This resulted in inefficient use of active control and dyscoordination of the upper extremity. The degree of interaction torque suppression and inefficiency of active control at the elbow positively correlated with stroke severity. The increased interaction torque suppression can be a strategy used by individuals with stroke to compensate for deficient feedforward control of this torque.     

All Behavior is choice: Revisiting an evolutionary theory's account of behavior on single schedules

The axiomatic principle that all behavior is choice was incorporated into a revised implementation of an evolutionary theory's account of behavior on single schedules. According to this implementation, target responding occurs in the context of background responding and reinforcement. In Phase 1 of the research, the target responding of artificial organisms (AOs) animated by the revised theory was found to be well described by an exponentiated hyperbola, the parameters of which varied as a function of the background reinforcement rate. In Phase 2, the effect of reinforcer magnitude on the target behavior of the AOs was studied. As in Phase 1, the AOs' behavior was well described by an exponentiated hyperbola, the parameters of which varied with both the target reinforcer magnitude and the background reinforcement rate. Evidence from experiments with live organisms was found to be consistent with the Phase-1 predictions of the revised theory. The Phase-2 predictions have not been tested. The revised implementation of the theory can be used to study the effects of superimposing punishment on single-schedule responding, and it may lead to the discovery of a function that relates response rate to both the rate and magnitude of reinforcement on single schedules.     

To be at the tail of the lions or the head of the foxes?

Agents seeking an opportunity for profit often have to compete with others who pursue the same opportunity. When having to choose between a number of opportunities differing in their value and if individuals differ in their chances of outperforming others, the choice can be cognitively and emotionally demanding. We explore choice between opportunities using stylized Lions–Foxes games. In such a game, each of three players, with different odds of beating others, has to choose one of two contests that offer different rewards. After game theoretically analyzing the games, which we have experimentally employed, we report four experiments that vary in choice elicitation (repeated play or strategy method), in players' matching (random strangers or partners) and in rewards. Regarding contest choices, we found the choice of the higher value (and seemingly more prestigious) contest to be positively related to winning odds, contrary to what four out of the five (mixed, partially mixed, or pure) equilibria predict. Participants started out rather optimistic, with a large majority choosing the higher value option, but with experience, they approached the only viable of two pure strategy equilibria. Still, mixing continued via reacting to past play and outcome, apparently balancing dissatisfaction from choosing either contest.     

The violent adolescent: the urge to destroy versus the urge to feel alive

The dynamics of adolescent violence are explored from theoretical and developmental perspectives applied to the review of psychoanalytic studies of violence and three cases: the case of Willie Bosket, presented in Fox Butterfield's All God's Children, an adolescent treated by one of the authors, and observation of staff dynamics in a juvenile detention facility. Studies indicate that violence is used to preserve a sense of existence and psychic equilibrium as well as to express rage and destroy unwanted projected parts of the self and dangerous intrusions into a fragile self-coherence. In the case studies, violent activity serves a number of psychic functions: it leads to high arousal states and the feeling of being alive thereby disavowing underlying feelings of deadness and depression, it serves to contain and discharge overwhelming chaotic and rageful feelings, and it enacts object ties and the unconscious fantasies of the parent. Staff dynamics in a treatment setting for juvenile offenders reflect the intrapsychic dynamics of the juvenile offender prone to acting out, projection, hypervigilance to signs of disrespect, and disavowal of unwanted affects including helplessness and vulnerability.     

Scharffs' Application of Hopper's Concept: “Incohesion: Aggregation/Massification”

We begin by stating our understanding of the concepts presented in Hopper's paper, then comment on the clinical illustration, and conclude by describing two group situations in which we have applied the concepts we have taken from Hopper's paper. Hopper's fourth basic assumption applies to our work as individual psychoanalysts, family therapists, and group leaders because it integrates psychoanalytic and social understanding. We demonstrate how and why we find Hopper's idea to be a useful advance.     

Learning from experience in case conference: A Bionian approach to teaching and consulting

In case conferences as well as didactic seminars, the power of the group can bring psychoanalytic education to life. However, primitive anxieties activated by group dynamics may also interfere with teaching and learning. The authors offer the example of a stalemated private practice case conference that had unconsciously organized against learning as the members began to read Bion's work. The case conference leader, an analyst, presented her case conference, which was mired in basic assumption dependency dynamics, to our peer consultation group. Drawing upon Bion's early contributions on groups, as well as his later ideas about thinking and mental growth, the peer group facilitated the case conference's return to work-group functioning and learning from experience. Activated in the peer group, commensal container↔contained processes gradually spread throughout the entire relational system of peer group, case-conference leader, case-conference members, and patients. This example underscores the importance of promoting within our institutes a culture in which faculty view themselves as part of an evolving intersubjective matrix that works to foster the containing capacities of candidates, patients, and faculty alike.     

Numerical representation and cross-cut role assignments: Majority members’ responses under cooperative interaction

This research investigates why cross-cutting role assignments, compared to those that converge, may worsen the intergroup attitudes of numerical majorities. Study 1 manipulated the numerical representation of groups and role assignments in a cooperative setting. As predicted, when the cross-cut role condition included the reintroduction of the numerical imbalance, the intergroup attitudes of majorities were more favorable than when the cross-cut condition did not reintroduce this discrepancy. Also, Study 1 showed that the intergroup attitudes of the majority were more positive when roles converged. Study 2 compared a convergent condition to one with converging roles that also reduced the salience of the majority’s numerical advantage. The results for this convergent-reduced-salience condition mimicked that of the cross-cut condition, revealing less positive majority attitudes. In both studies, results suggest that the processes of ingroup identification and relative ingroup homogeneity may mediate the effect of role assignments on ingroup bias. The findings are discussed in terms of the implications for cooperative interventions designed to improve intergroup attitudes.     

Aggression and school social dynamics: The good, the bad, and the ordinary

A social dynamics perspective of aggression in school is presented. This framework focuses on the role of natural social processes in the establishment and maintenance of aggressive behavior in the school context. The five articles in this special issue are briefly reviewed and a synthesis of their contributions for understanding the social dynamics of aggression in school is underscored. Future research and intervention implications are also discussed. The need for examining the role of school social dynamics in conducting social skills interventions, functional behavioral assessments, and the development of positive behavioral support plans is emphasized.     

Conceptual Hierarchies in a Flat Attractor Network: Dynamics of Learning and Computations

The structure of people's conceptual knowledge of concrete nouns has traditionally been viewed as hierarchical ( Collins & Quillian, 1969 ). For example, superordinate concepts ( vegetable ) are assumed to reside at a higher level than basic-level concepts ( carrot ). A feature-based attractor network with a single layer of semantic features developed representations of both basic-level and superordinate concepts. No hierarchical structure was built into the network. In Experiment and Simulation 1, the graded structure of categories (typicality ratings) is accounted for by the flat attractor network. Experiment and Simulation 2 show that, as with basic-level concepts, such a network predicts feature verification latencies for superordinate concepts ( vegetable ). In Experiment and Simulation 3, counterintuitive results regarding the temporal dynamics of similarity in semantic priming are explained by the model. By treating both types of concepts the same in terms of representation, learning, and computations, the model provides new insights into semantic memory.