Why We Walk the Way We Do

By using inverse dynamics and forceplate recordings, this study established the principle of oscillating systems and the influence of gravity and body parameters on the programming of the gait parameters, step frequency and length. Calculation of the ratio of the amplitude of the center of mass (CM) and the center of foot pressure (CP) oscillations yielded an equation and established a biomechanical constant, the natural body frequency (NBF). NBF appears to be an absolute invariant parameter, specific to human standing posture and gait in terrestrial gravity, which influences the relative positions of CM and CP and whose value separates the frequency bands of standing posture from those for gait. This equation was tested by using the experimental paradigm of stepping in place and then used in calculating the magnitude of CM oscillations during gait. The biomechanical analysis of the experimental observations allows one to establish the relationships between body parameters and gravity and the central programming of locomotor parameters.     

Postural Requirements and Progression Velocity in Young Walkers

This article describes developmental changes in gait velocity and relates these changes to gait parameters that index postural stability (step width and lateral acceleration) and two components of velocity (cadence and step length).

Five children were observed longitudinally over a 2-year period after onset of independent walking. Their range of speed increased threefold in the first 6 months of independent walking and then remained constant. In contrast, step width decreased approximately twofold. Whereas in adults, cadence and step length contribute approximately equally to speed, when infants first begin to walk independently, increase in velocity is due mostly to increased step length. After 5 months of independent walking, the pattern reverses, and increase in velocity is due primarly to increased cadence. The pattern remains constant over the next 18 months. From a developmental point of view, the data lead us to interpret early walking (the first 5 months) as a process of integration of postural constraints into the dynamic necessities of gait movement. A second phase, beginning after 4 to 5 months of independent walking, is considered to be a tuning phase characterized by a more precise adjustment of the gait parameters.     

Coordination Dynamics of the Bipedal Galloping Pattern

A motion equation in relative phase was developed that incorporates the spatial-temporal pattern of the bipedal gallop along with the more commonplace patterns of the bipedal jump and walk-run. In 3 experiments, human participants (N = 6 per experiment) simulated the bipedal gait patterns through the rhythmic motions of hand-held pendulums. Predictions of the motion equation for coordination equilibria and their respective degrees of stability were confirmed. In particular, the gallop pattern was less stable than the fundamental in-phase and antiphase patterns but changed in qualitatively similar ways to those gaits as a function of limb asymmetry and movement frequency. The relation between the modeled coordination dynamics and the kinematic characteristics of real bipedal galloping is discussed.     

Psychometric Properties and Clinical Cut-Off Scores of the Spanish Version of the Social Anxiety Scale for Adolescents

Psychotic (P) and Non-Psychotic (N-P) retardates were compared on 13 Rorschach “indicators” of psychosis using a matched pairs technique. Two of the 13 signs were found to significantly differentiate between groups with the P group demonstrating a lower F% and higher C' responding than the N-P group.     

“We will work for you” – Social influence may suppress individual food preferences in a communicative situation in dogs

The level of motivation (i.e. incentive power) is thought to be one of the most important factors affecting performance and learning in various tasks. We investigated whether reward quality has an effect on the performance of family dogs in a two-way object choice test in which they can find the hidden food by relying on distal momentary human pointing cues. In three experiments we varied (1) the type of food reward according to the subjects’ own preference; (2) the quality of the reward offered at the same time in the indicated and not-indicated locations; and (3) the order of the high or low quality rewards in consecutive sessions. In Experiment 1, we first tested whether dogs prefer one kind of reward over another. Then one group was tested with the ‘preferred’ food as reward in the indicated bowl, while dogs in the other group received the ‘non-preferred’ food as reward. We did not find any difference between the performance and choice latencies of the two groups. In Experiment 2 for the first group, the indicated bowl contained a piece of carrot and the not-indicated bowl was empty. In the second group the indicated bowl contained carrot, but the not-indicated bowl contained sausage. According to a preliminary preference test, most dogs prefer sausage over carrot invariably. After 20 trials, the two groups performed surprisingly similarly. There was no difference found between groups in the number of correct choices, incorrect choices and non-choices. However, the comparison between the first and last five trials revealed that subjects who found sausage when they chose the not-indicated bowl (did not follow the pointing) chose the non-indicated bowl significantly more often toward the end of their test session. In Experiment 3, each dog received two sessions with 12 pointing trials in each. For the first session, one group was rewarded with sausage and the other with carrot upon choosing the indicated bowl. In the second session, the indicated bowl contained dry dog food for both groups. We found that correct choices and response latencies did not change over two sessions in the ‘sausage’ group. In the ‘carrot’ group, the dogs chose faster in the second session, but their performance did not improve; in fact, they chose the not-indicated bowl more often than the indicated bowl. As a conclusion, we can say that reward quality had some effect on dogs’ choice behavior in these experiments. The drop in their performance was not drastic, taking into account the general refusal to eat one of the ‘rewards’ (carrot) during the preference tests and also during the test trials. It seems that incentive contrast may play a relatively minor role in dog-human social interactions. Appropriate reward quality can be very important in asocial problem solving tasks, but, when interacting with humans, following human signals may override the effect of changed incentive power.     

Self-Induced Water Intoxication in a Psychiatric Asylum: A Case Study of Diagnostic Categorization and Regulation

In this article, we examine the regulation of psychiatric patients becoming intoxicated from drinking excessive amounts of liquids at a large psychiatric asylum in Canada. We analyze how medical staff created a formalized diagnostic category and a specialized ward for its treatment. We consider the institutional context in which “water intoxication” was developed as a diagnostic category and we examine the impact of this diagnosis on the regulation of asylum patients. Finally, we discuss the patients’ opposition to treatment as well as the impact of “water intoxication” on their self-identity and institutional status.     

Efectos de anticipación y de stroop en tareas de denominación y categorización de dibujos y de palabras

Resumen

Se llevó a cabo un experimento con vistas a estudiar el procesamiento de dibujos y de palabras en el marco de los paradigmas de Stroop y de anticipación. Las variables de tarea, modalidad y de relación semántica fueron equivalentes en ambos paradigmas. Según el intervalo temporal entre los estímulos se establecieron tres condiciones experimentales: condición previa—anticipación—, condición simultánea—Stroop—, y condición previa y simultánea—Stroop y anticipación—. Los resultados ponen de manifiesto la existencia de efectos de facilitación e interferencia de signo opuesto que se atribuyen a la interacción entre la secuencia temporal entre los estímulos componentes, las demandas de las respectivas tareas y la modalidad en la memoria activa. Los resultados se discuten en relación con el diferente procesamiento a que se someten los dibujos y las palabras y la naturaleza del formato de representación.     

Entrevista con Jean-Paul Bronckart

RESUMEN

Bronckart comienza revisando su trayectoria científica y explicando cuáles son sus dos enfoques básicos: el análisis del contexto o de situaciones y el análisis del lenguaje en función de sus operaciones subyacentes definidas en el marco de las teorías de la enunciación. Seguidamente justifica su renuncia a posiciones estructuralistas porque no tienen en cuenta el problema de las relaciones funcionales ni prestan atención al contexto. El autor relaciona las operaciones psicológicas con universales funcionales diferenciándolos de los estructurales de Chomsky y del enfoque de Searle, defendiendo su interés por la lingüística comparativa. Seguidamente aborda el tema de análisis de textos en ambientes escolares, sugiriendo que hay que sensibilizar a los educadores sobre el hecho de que constantemente estamos en situaciones de comunicación que van cambiando y crear instrumentos para que puedan analizar su propia práctica. Con relación al aspecto cognitivo del lenguaje, enfatiza la proliferación excesiva de los enfoques representativos y seguidamente desarrolla qué entiende por especificidad de la naturaleza del lenguaje y de su carácter comunicativo. Esta entrevista aborda, además, cuestiones tales como el fenómeno presuposicional, las aportaciones de Vygotsky o las experiencias de enseñar lenguaje a chimpancés, y finaliza planteando algunos aspectos de la teoría de Culioli.     

Personalidad,estrategias cognitivas y tiempo de Inspección

Resumen

En el presente trabajo se han empleado las medidas cronométricas de Tiempo de Inspección (TI) y Tiempo de Reacción (TR) para estudiar los efectos de las diferencias individuales en extroversion sobre una tarea de discriminación perceptual. Para ello se utilizaron dos grupos de sujetos que habían obtenido puntuaciones máximas y mínimas en la dimensión Extraversión del Test EPI de H. J. Eysenck. Se postuló que los extrovertidos obtendrían un TI más corto que los introvertidos y asimismo un TR también más corto, de acuerdo a los modelos de Brebner (1980) y Tous (1986). Los resultados indicaron que si bien existieron diferencias entre extrovertidos e introvertidos en cuanto a las medidas cronométricas, estas dit erencias dependieron del uso diferencial de estrategias de resolver la tarea que fueron utilizadas por estos sujetos.