Influence of delayed muscle reflexes on spinal stability: Model-based predictions allow alternative interpretations of experimental data

Model-based calculations indicate that reflex delay and reflex gain are both important for spinal stability. Experimental results demonstrate that chronic low back pain is associated with delayed muscle reflex responses of trunk muscles. The aim of the present study was to analyze the influence of such time-delayed reflexes on the stability using a simple biomechanical model. Additionally, we compared the model-based predictions with experimental data from chronic low back pain patients and healthy controls using surface-electromyography. Linear stability methods were applied to the musculoskeletal model, which was extended with a time-delayed reflex model. Lateral external perturbations were simulated around equilibrium to investigate the effects of reflex delay and gain on the stability of the human lumbar spine. The model simulations predicted that increased reflex delays require a reduction of the reflex gain to avoid spinal instability. The experimental data support this dependence for the investigated abdominal muscles in chronic low back pain patients and healthy control subjects. Reflex time-delay and gain dependence showed that a delayed reflex latency could have relevant influence on spinal stability, if subjects do not adapt their reflex amplitudes. Based on the model and the experimental results, the relationship between muscle reflex response latency and the maximum of the reflex amplitude should be considered for evaluation of (patho) physiological data. We recommend that training procedures should focus on speeding up the delayed reflex response as well as on increasing the amplitude of these reflexes.     

Reliability and plasticity of response inhibition and interference control

This study investigated the internal reliability, temporal stability and plasticity of commonly used measures of inhibition-related functions. Stop-signal, go/no-go, antisaccade, Simon, Eriksen flanker, Stroop and Continuous Performance tasks were administered twice to 23 healthy participants over a period of approximately 11 weeks in order to assess test–retest correlations, internal consistency (Cronbach’s alpha), and systematic between as well as within session performance changes. Most of the inhibition-related measures showed good test–retest reliabilities and internal consistencies, with the exception of the stop-signal reaction time measure, which showed poor reliability. Generally no systematic performance changes were observed across the two assessments with the exception of four variables of the Eriksen flanker, Simon and Stroop task which showed reduced variability of reaction time and an improvement in the response time for incongruent trials at second assessment. Predominantly stable performance within one test session was shown for most measures. Overall, these results are informative for studies with designs requiring temporally stable parameters e.g. genetic or longitudinal treatment studies.     

The Imaginary Lovers Delusion: A Diagnostic Case Study

A patient who believed that two imposters were posing as her and her ex-fiance was diagnosed as a paranoid schizophrenic with the aid of the Rorschach, DAP and Hand Test. Projective tests not only accurately reflected various elements of the girl's psychopathology but also revealed certain voyeuristic tendencies which appeared to be related to the projection of a double. The delusion was tentatively classified as a variation of Capgras' syndrome.     

Delayed timeout as a procedure for reducing disruptive classroom behavior: a case study

The disruptive behavior of a 9-yr-old boy was eliminated by the illumination of a light on the subject's desk, which represented the loss of free time later in the day. Instructions alone failed to reduce the frequency of disruptive behavior. When the light was removed and disruptive behavior no longer resulted in a loss of free time, disruptive behavior returned to its previous level.     

The time-course of recovery from interruption during reading: eye movement evidence for the role of interruption lag and spatial memory

Two experiments examined how interruptions impact reading and how interruption lags and the reader's spatial memory affect the recovery from such interruptions. Participants read paragraphs of text and were interrupted unpredictably by a spoken news story while their eye movements were monitored. Time made available for consolidation prior to responding to the interruption did not aid reading resumption. However, providing readers with a visual cue that indicated the interruption location did aid task resumption substantially in Experiment 2. Taken together, the findings show that the recovery from interruptions during reading draws on spatial memory resources and can be aided by processes that support spatial memory. Practical implications are discussed.     

Agreement and movement: a syntactic analysis of attraction

This paper links experimental psycholinguistics and theoretical syntax in the study of subject-verb agreement. Three experiments of elicited spoken production making use of specific characteristics of Italian and French are presented. They manipulate and examine its impact on the occurrence of 'attraction' errors (i.e. incorrect agreement with a word that is not the subject of the sentence). Experiment 1 (in Italian) shows that subject modifiers do not trigger attraction errors in free inverted VS (Verb Subject) structures, although attraction was found in VS interrogatives in English (Vigliocco, G., & Nicol, J. (1998). Separating hierarchical relations and word order in language production. Is proximity concord syntactic or linear? Cognition, 13-29) In Experiment 2 (in French), we report stronger attraction with preverbal clitic object pronouns than with subject modifiers. Experiment 3 (in French) shows that displaced direct objects in the cleft construction trigger attraction effects, in spite of the fact that the object does not intervene between the subject and the verb in the surface word order (OSV). Moreover, attraction is stronger in structures with subject-verb inversion (...). These observations are shown to be naturally interpretable through the tools of formal syntax, as elaborated within the Principles and Parameters/Minimalist tradition. Three important constructs are discussed: (1) the hierarchical representation of the sentence during syntactic construction, and the role of intermediate positions by which words transit when they move; (2) the role of specific hierarchical (c-command) but also linear (precedence) relations; and (3) the possibility that agreement involves two functionally distinct components. A gradient of computational complexity in agreement is presented which relates empirical evidence to these theoretical constructs.     

Origins of the misplaced confidence effect in collaborative recall

Studies have shown that dyads and groups place significantly more confidence in wrong answers to questions about a jointly witnessed event than do individuals. This experiment was designed to discover whether this misplaced confidence is influenced by prior free collaborative recall of the events in question. The results clearly indicated that prior group remembering lessens the effect, and improves the testimonial validity of both individual and group answers to questions about a jointly witnessed event. Taken in conjunction with other studies, the results imply that two or more witnesses of an event may profitably discuss what happened, but that they may best be interrogated separately in order to maximize the information available to the interrogator and to minimize misplaced confidence.     

Treatment Foster Care in a System of Care: Sequences and Correlates of Residential Placements

We examined Treatment Foster Care (TFC) in residential trajectories for youth with psychiatric disorders and aggressive behavior. We analyzed residential placements of a statewide sample of youth during the 12 months preceding and following admission to TFC. Prior to TFC, the majority of youth were residing in more restrictive settings (group homes or residential treatment). Two-thirds of youth remained in TFC throughout the follow-up year. Of those who left, nearly half returned home, and slightly fewer were discharged to group homes. By the end of the 12-month follow-up period, rates of group home use were similar to those seen in the pre-TFC period. Movement out of TFC during the year was associated with being older at placement and with increased problem behavior (particularly externalizing behaviors). TFC serves as a step-down placement for a substantial number of youth. However, this is not the only way it is used, and models based on short-term transitioning or reunification with families may not be widely implemented or relevant in practice. Additional research is needed to understand current functions of TFC in residential trajectories and to maximize its utility in systems of care.