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1.
Asclepio ; 65(1): 1-12[6], ene.-jun. 2013. ilus
Artigo em Espanhol | IBECS | ID: ibc-115046

RESUMO

El presente artículo se orienta a la reconstrucción de los modelos cosmológicos de la escuela de Cachemira (s. IV), registrados en el compendio de la escuela sarvāstivāda-vaibhāsika titulado Abhidharmakośabhāsya, atribuido al monje budista Vasubandhu. Se identifican algunas de las fuentes textuales que dieron lugar a estos modelos y se describe con detalle su estructura general, compuesta de tres ámbitos (sensible, materia sutil e inmaterial). Se analizan algunas de las características más relevantes del espacio y del tiempo y su relación con la vida consciente, descubriéndonos unos modelos cosmológicos inéditos entre sus contemporáneas grecolatinos (AU)


The present article focuses on the reconstruction of the cosmological models from the school of Kashmir (fourth century), as they are registered in the compendium of sarvāstivāda-vaibhāsika school, attributed to the Buddhist monk Vasubandhu and titled Abhidharmakośabhāsya. The articles identifies the different textual sources of the cosmological models and describes its general structure, based in three realms (sensible, subtle matter and immaterial). It analyzes the relevant characteristics of the concepts of Space and Time, discovering and unusual model in comparison with the contemporaries cosmologies from the Mediterranean (AU)


Assuntos
Humanos , Masculino , Feminino , Existencialismo/história , Existencialismo/psicologia , Processos Mentais/ética , Competência Mental/classificação , Competência Mental/psicologia , Física/história , Disciplinas das Ciências Naturais/história , Ciência/história , Movimento (Física)
2.
Cuad. psicol. deporte ; 12(2,supl): 23-30, jul.-dic. 2012. ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-125359

RESUMO

El objetivo de este estudio fue examinar la fiabilidad absoluta de las pruebas de estimación de la flexibilidad de la musculatura del tríceps sural ROM-soleo y ROM-gemelo a través de un diseño de medidas repetidas. 25 jugadores senior de balonmano completaron 3 sesiones de evaluación del ROM articular de la dorsi-flexión del tobillo con rodilla flexionada (ROM-soleo) y extendida (ROM-gemelo) con un intervalo de 2 semanas entre sesiones consecutivas. La fiabilidad absoluta fue examinada mediante el cálculo de los estadísticos cambio en la media (CM) entre sesiones de valoración, porcentaje del error (..) (AU)


The purpose of this study was to examine the absolute reliability of both ROM-soleus and ROM-gastrocnemic tests for estimating triceps surae flexibility throughout a repeated measures design. 25 senior handball players completed 3 measurement sessions of dorsi-flexion ankle ROM with knee flexed (ROM-soleus) and extended (ROM-gastrocnemic) with a 2-weeks rest interval between consecutive sessions. The absolute reliability was (..) (AU)


Assuntos
Humanos , Masculino , Adulto , Fenômenos Biomecânicos/fisiologia , Amplitude de Movimento Articular , Movimento (Física) , Esportes/fisiologia , Reprodutibilidade dos Testes , Reprodutibilidade dos Testes , Variações Dependentes do Observador
3.
Psicológica (Valencia, Ed. impr.) ; 33(3): 451-471, 2012. ilus
Artigo em Inglês | IBECS | ID: ibc-102518

RESUMO

This is an intuitive physics study of collision events. In two experiments the participants were presented with a simulated 3D scene showing one sphere moving horizontally towards another stationary sphere. The moving sphere stopped just before colliding with the stationary one. Participants were asked to rate the positions which both spheres would have reached after a fixed time if the collision had really occurred. The simulated masses of both spheres and the velocity of the moving one were manipulated. Specifically, in Experiment 1 different implied masses were defined by varying only the size of the spheres; in Experiment 2, different implied masses were defined by varying both the size and the apparent texture (material) of the spheres. Functional Measurement was used to compare the physical laws of collision events with cognitive integration rules. Cognitive rules proved to be more similar to physical laws in Experiment 2, i.e., when both spheres size and apparent texture were manipulated. Surprisingly, in both experiments only half the participants took into account the possibility that the moving sphere could have bounced back after the collision. These and other results are important for teaching elementary physics(AU)


Assuntos
Humanos , Masculino , Feminino , Adulto , Simulação/métodos , Testes Psicológicos , Ciência Cognitiva/métodos , Ciência Cognitiva/estatística & dados numéricos , Estudantes/psicologia , Estudantes de Ciências da Saúde/psicologia , Movimento (Física) , Análise Fatorial , Análise de Variância
4.
Asclepio ; 63(1): 179-192, ene.-jun. 2011.
Artigo em Espanhol | IBECS | ID: ibc-90496

RESUMO

Este artículo examina la traducción hecha por Diego Hurtado de Mendoza de la Mecánica aristotélicaen el contexto del ambiente científico-humanista italiano de mediados del siglo XVI. Apartir del análisis de los últimos problemas sobre dinámica, se demuestra su estrecha relación conlas obras de Piccolomini y Cardano; sugiriéndose además la originalidad de la interpretación hechapor el autor español del problema XXXIV basada en la combinación de la física tardomedieval y laexplicación aristotélica(AU)


This article considers Diego Hurtado de Mendoza’s translation of the Aristotelian Mechanics inrelation to the humanistic and scientific Italian environment of the Renaissance. From the analysisof the last problems on dynamics, it demonstrates the affinity with the works of Piccolomini andCardano. It also shows the originality of the exegesis made by the Spanish author of ProblemXXXIV, in which he combines latemedieval physics with the Aristotelian explanation(AU)


Assuntos
Humanos , Mecânica , Física , Movimento (Física) , Ar
5.
An. sist. sanit. Navar ; 31(2): 159-170, mayo-ago.2008. ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-67368

RESUMO

Dentro de cualquier población de individuos mayores de 65 años, una proporción sustancial (entre el 6% y el 25%) sufre diferentes síntomas del síndrome de fragilidad. A pesar de la complejidad del terminó fragilidad y de las imprecisiones en cuanto a su definición existe un consenso sobre sus síntomas y signos. Las personas que poseen este síndrome presentan pérdidas de fuerza muscular, fatiga, disminución de la actividad física, con un aumento del riesgo de padecer anorexia-pérdida de peso, delirium, hospitalización, declive funcional, deterioro cognitivo, mortalidad, ingreso en residencias, caídas e inestabilidad. Bajo este contexto, surge la necesidad de desarrollar tests que sean capaces de predecir de la forma más precoz posible la fragilidad y la discapacidad. La acelerometría es una herramienta adecuada para la monitorización de movimientos humanos de una forma objetiva y fiable, aplicable en la vida diaria de los sujetos sin implicar grandes costes. Los acelerómetros están siendo utilizados en la monitorización de diferentes movimientos. Se pueden obtener un amplio abanico de medidas como: clasificación de movimientos, valoración del nivel de actividad física, estimación del gasto de energía metabólica, medida del equilibrio, ritmo de marcha y control al levantarse-sentarse. Combinando la acelerometría con giróscopos y magnetómetros se podrá añadir información relacionada con la orientación y los cambios de posición. Esta revisión analiza las herramientas y tecnologías existentes que puedan llegar a detectar de manera precoz posibles signos y síntomas de la fragilidad y permitan a los individuos vivir autónomamente de forma más prolongada y en condiciones de mayor seguridad (AU)


If we consider a population of free-living individuals, who are 65 years old and even older, a substantial proportion (in the range of 6% to 25%) suffers from many of the elements of the syndrome of frailty. Although the syndrome is complex and still lacks a standard definition, there is a growing consensus about its signs and symptoms. Patients who are afflicted with frailty typically exhibit losses of muscle strength, fatigue easily, are physically inactive, with an increased risk (and fear) of falling, have undergone a recent, unintentional loss of weight, experience impaired cognition and depression, all of which is frequently complicated by a variety of coexistent illnesses. In this context, functional tests to predict disability and frailty are needed. Accelerometry offers a practical and low cost method of objectively monitoring human movements, and has particular applicability to the monitoring of disability in an aging population. Accelerometers have been used to monitor a range of different movements, including gait, sit to stand transfers and postural sway. This review focuses on methodological concepts in the evaluation of skeletal muscle function and monitoring systems (accelerometers and gyroscopes) in each of these areas. An integrated approach is described in which a combination of accelorometry and gyroscopy can be used to monitor a range of different parameters (muscle power, gait and balance) in an aging population in a clinical or out-patient setting (AU)


Assuntos
Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Monitorização Fisiológica/instrumentação , Envelhecimento/fisiologia , Marcha/fisiologia , Postura/fisiologia , Aceleração , Contração Muscular/fisiologia , Miografia/métodos , Músculos/fisiologia , Fisiologia/instrumentação , Acelerógrafo , Movimento/fisiologia , Movimento (Física) , Manifestações Neuromusculares , Miografia/instrumentação , Miografia/tendências , Miografia , Atividade Motora/fisiologia
6.
Rev. esp. med. nucl. (Ed. impr.) ; 27(3): 191-198, mayo 2008. tab
Artigo em Inglês | IBECS | ID: ibc-147871

RESUMO

Objective. Iron overload limits the life expectancy of thalassaemic patients by causing cardiac toxicity. Iron also plays a catalytic role in the pathogenesis of atherosclerosis. The aim of this study was to evaluate the role of 99mTc Tetrofosmin gated myocardial perfusion scintigraphy (GMPS) in the detection of cardiac dysfunction in patients with thalassemia major. Materials and methods. Forty two patients with homozygous beta-thalassemia were enrolled in the study. Myocardial perfusion and wall motion were analysed in all patients (mean age 17 ± 5.28) and 34 age-matched controls using GMPS. Clinical data, liver function tests, hemoglobin, ferritin, low density lipoprotein (LDL) and cholesterol levels, and the total number and frequency of transfusions were collected from patient records. Results. 97.6 % and 78.5 % of patients had normal myocardial perfusion and wall motion respectively. Nine out of 42 thalassaemic patients had abnormal left ventricular wall motion; half of these had septal hypokinesia. No significant correlation was found between the total number of transfusions, serum ferritin levels and left ventricular ejection fraction (p = 0.442 and p = 1.00, respectively). Echocardiography revealed systolic dysfunction in 5 out of 9 patients with wall motion abnormality. LDL was normal in 38 out of 42 patients and cholesterol levels were normal in 37 out of 42 patients. Conclusions. Regional wall motion abnormalities can be seen in patients with thalassemia major. This early damage is frequently located in the septum and can be detected by GMPS. Serum ferritin levels and the number of blood transfusions are inadequate as predictors of myocardial dysfunction (AU)


Objetivo. La sobrecarga de hierro limita la esperanza de vida de los pacientes talasémicos debido a su toxicidad cardiaca. El hierro también tiene un papel catalítico en la patogénesis de la aterosclerosis. El objetivo de este estudio era evaluar el papel de la gammagrafía de perfusión miocárdica con 99mTc tetrofosmina (GPM) en la detección de disfunción cardiaca en pacientes con talasemia mayor. Materiales y métodos. En el estudio se incluyeron 42 pacientes con beta talasemia homocigota. Se analizó la perfusión miocárdica y el movimiento de la pared cardiaca mediante GPM en todos los pacientes (edad media 17 ± 5,28 años) y 34 controles de edad comparable. Se registraron los datos clínicos, las pruebas de función hepática, los niveles de hemoglobina, ferritina, lipoproteína de baja densidad (LDL) y colesterol, y el número total y la frecuencia de transfusiones a partir de los informes de los pacientes. Resultados. El 97,6 y el 78,5 % de los pacientes mostraron normalidad en la perfusión miocárdica y el movimiento de la pared cardiaca, respectivamente. En 9 de 42 pacientes talasémicos se observó un movimiento anómalo de la pared ventricular izquierda, y la mitad de ellos mostraron hipocinesia septal. No se observó una correlación significativa entre el número total de transfusiones, los niveles de ferritina sérica y la fracción de eyección del ventrículo izquierdo (p = 0,442 y p = 1,00, respectivamente). La ecocardiografía reveló una disfunción sistólica en 5 de los 9 pacientes con movimiento anómalo de la pared cardiaca. El nivel de LDL fue normal en 38 de 42 pacientes, y el nivel de colesterol fue normal en 37 de 42 pacientes. Conclusiones. En pacientes con talasemia mayor se pueden observar alteraciones regionales del movimiento de la pared cardiaca. Esta alteración precoz suele localizarse en el tabique interventricular y puede detectarse mediante GPM. Los niveles de ferritina sérica y el número de transfusiones de sangre no son adecuados como factores de pronóstico de disfunción miocárdica (AU)


Assuntos
Humanos , Masculino , Feminino , Criança , Adolescente , Adulto , Imagem do Acúmulo Cardíaco de Comporta , Isquemia Miocárdica/etiologia , Isquemia Miocárdica , Compostos Organofosforados , Compostos de Organotecnécio , Compostos Radiofarmacêuticos , Disfunção Ventricular Esquerda , Talassemia beta/complicações , Transfusão de Sangue/efeitos adversos , Terapia por Quelação , Terapia Combinada , Desferroxamina/uso terapêutico , Ferritinas/sangue , Teste de Esforço , Septos Cardíacos/fisiopatologia , Septos Cardíacos , Quelantes de Ferro/uso terapêutico , Sobrecarga de Ferro/etiologia , Imagem por Ressonância Magnética , Movimento (Física) , Método Simples-Cego , Disfunção Ventricular Esquerda/etiologia , Disfunção Ventricular Esquerda , Talassemia beta/sangue , Talassemia beta/tratamento farmacológico , Talassemia beta/terapia
7.
Arch. med. deporte ; 25(123): 19-28, ene.-feb. 2008. ilus, tab, graf
Artigo em Espanhol | IBECS | ID: ibc-86488

RESUMO

En la mayoría de los casos, el material y equipamiento deportivo es analizado y homologado mediante una serie de criterios normativos que emplean test mecánicos. En gimnasia, la recepción es una de las acciones más peligrosas y frecuentemente realizadas, la cual es ejecutada sobre una colchoneta homologada mediante estos test. Sin embargo, las lesiones siguen siendo altas, planteándose como objetivo en este estudio: analizar el efecto de las propiedades de la colchoneta sobre el gimnasta, así como la validez delos test mecánicos para predecir tales efectos. Para ello, se contó con la participación de cinco gimnastas, analizándoselas fuerzas de impacto, la aceleración (tibia y cabeza),y el rango de movimiento en las articulaciones coxo-femoral, rodilla, tibio-tarsiana y subastragalina, tras saltar sobre una muestra de seis colchonetas. Los resultados muestran como el gimnasta adapta su ejecución en función de las características de la colchoneta, con magnitudes de impacto medias de 4450 ± 195.34 N, valores máximos de deceleración de 15.57 ± 0.54 g en tibia y 4.72 ± 0.55 g encabeza, rangos de flexión medios de 72.18 ± 5.8º en la articulación coxo-femoral, 87.07 ± 6.29º en rodilla, 6.81± 10.23º en tibio-tarsiana, y rangos medios de pronación/supinación en la subastragalina de 15.96 ± 7.75º/ 13.56± 5.67º, respectivamente. Se observó cómo no todas las variables analizadas estuvieron correctamente contempladas en los test normativos, especialmente el mecanismo de prono-supinación en la articulación subastragalina. Esto permite pensar que los criterios normativos en las colchonetas podrían ser revisados considerando los efectos que la recepción produce en el gimnasta, fundamentalmente los relacionados con la estabilidad (o deformación de la colchoneta) y la absorción de los impactos, evitándose de este modo futuras lesiones (AU)


Certain material and sport equipment are analyzed by means of mechanical test suggested by standard criteria.In gymnastics, landing is one of the most important and dangerous actions that a gymnast takes, which are executed on a mat accredited by means of this test. Nevertheless, injuries continue being high, for this reason we considered as objective in this study: to analyze the effect of themat properties on gymnast, as well as the mechanical test validity to predict this effects. Five gymnasts participated in this study, and we analyzed impact forces, acceleration(shank and head), and range of motion on the knee, hip, tibiotarsal and subastragaloid joints, after landing on six mat. Results show as gymnast modulated his execution based on mat characteristics, with average reaction force of4450 ± 195.34 N, maximum deceleration of 15.57 ± 0.54g at the shank and 4.72 ± 0.55 g at the head, and average flexion movement of 72.18 ± 5.8º at the hip joint, 87.07 ±6.29º at the knee joint, 6.81 ± 10.23 at the ankle joint, and average of eversion/inversion movement of 15.96 ± 7.75º/13.56 ± 5.67º at the subastragaloid joint, respectively. Not all the biomechanical variables analysed were faithfully reproduced in the mechanical tests, especially the eversion/inversion movement at subastragaloid joint. This allows thinking that standard criteria on mats could be reviewed to consider the effects that landing cause on gymnast, related to stability (or mat deflection) and shock absorption essentially, avoiding several injuries during gymnast landing in a future (AU)


Assuntos
Equipamentos Esportivos/efeitos adversos , Equipamentos Esportivos/estatística & dados numéricos , Aceleração/efeitos adversos , Traumatismos em Atletas/diagnóstico , Traumatismos em Atletas/patologia , Traumatismos em Atletas/prevenção & controle , Fenômenos Biomecânicos/instrumentação , Fenômenos Biomecânicos/métodos , Fenômenos Biomecânicos/estatística & dados numéricos , Análise de Variância , Movimento (Física) , Tíbia/anatomia & histologia , Tíbia/fisiopatologia , Joelho , Traumatismos do Joelho/diagnóstico , Traumatismos do Joelho/prevenção & controle , Traumatismos do Joelho/fisiopatologia
8.
Asclepio ; 58(1): 113-148, ene.-jun. 2006. ilus
Artigo em Espanhol | IBECS | ID: ibc-050804

RESUMO

Este artículo aborda las concepciones acerca de los indivisibles que Galileo expuso en los Discorsi y explora su aplicación al estudio de los movimientos uniformemente acelerados. Propone reconsiderar el concepto de velocidad "total" atribuido a Galileo interpretándolo, no como una superficie, sino como una colección infinita de grados de velocidad. Asimismo se sugiere interpretar el momento de la velocidad como la medida de la aceleración, lo que contribuye a tender un puente entre las concepciones de Galileo y de Newton


This paper discusses the conceptions about indivisibles displayed in Galileo´s Discorsi, and explores their application to the study of uniformement accelerated motions. I suggest to reconsider the holistic velocity concept that has been attributed to Galileo and to interpret ir as an infinite collection of velocity degrees. I also suggest interpret the moment of velocity as the measurement of acceleration. This can contribute to fill the gap between the conceptions of Galileo and Newton


Assuntos
Humanos , Aceleração , Mecânica , Movimento (Física) , Disciplinas das Ciências Naturais/história
9.
Arch. med. deporte ; 22(108): 285-292, jul.-ago. 2005. ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-040916

RESUMO

El objetivo de este estudio se ha centrado en medir las fuerzas de reacción en diferentes movimientos (marcha, carrera, cambio de dirección y amortiguación de caída) en una muestra de sujetos sedentarios sanos con pies planos y cavos. Participaron en el estudio 15 mujeres jóvenes (edad: 19,4 +/- 1.3 afios; peso: 57,17 +/- 8,98 Kg); 8 con pies planos (P) y 7 con pies cavo s (C). Fueron sometidas a una batería de pruebas: marcha (velocidad = 1,6 mis), carrera (velocidad = 3 mis), amortiguación de caída (desde una altura de 0,75 m) y cambio de dirección. Se estudiaron las fuerzas verticales, anteroposteriores y mediolaterales, utilizando una plataforma de fuerzas piezoeléctrica. Aparecieron diferencias significativas (p<0,01) entre pies planos y cavos en la duración del apoyo en el cambio de dirección, siendo mayores en los planos (C = 0,30 +/- 0,04 s Y P = 0,37 +/- 0,04 s) y en el primer pico de fuerza de la amortiguación de la caída (p<0,05), con valores superiores en los cavos (C = 5,78 +/- 1,29 BWy P = 4,29 +/- 0,84 BW). El resto de variables estudiadas no mostraron diferencias significativas, aunque todos los picos de fuerza en los movimientos máximos fueron mayores en el grupo con pies cavos y los picos de impacto en marcha y carrera fueron ligeramente superiores en los pies planos. El grado de significación estadística no tiene por qué ser el límite que marque el mayor o menor riesgo de futura lesión asociada a las fuerzas de reacción. Pequefias y no significativas diferencias podrían marcar un incremento sustancial del riesgo. Cabe destacar los mayores valores registrados en los pies cavos, en los movimientos máximos, en los que existiría un mayor riesgo para ellos. Por otro lado las mínimas o nulas diferencias observadas en los patrones de movimiento podrían explicarse por adaptaciones que realiza el sujeto en el movimiento


The aim of this study was to measure the ground reaction force s in different movements (walking, running, changes of direction and landing), in a sample of sedentary subjects with high-arch feet or flat feet. Fifteen young women volunteered for the study (age: 19,40 +/- 1,29 years; weight: 57,17 +/- 8,98 Kg); 8 with flat feet (P) and 7 with high -arch feet (C). AlI of them carried out the following tests on a force platform: walking (speed = 1,6 mis), running (speed = 3 mis), drop landing (height = 0,75 m), and changes of direction. Vertical, horizontal and mediolateral ground reaction forces were collected using a piezoelectric force platform. There were significant differences (p < 0,01) between flat and high-arch feet in the contact time during the change of direction test, with greater contact times in subjects with flat feet (C = 0,30 +/- 0,04 s Y P = 0,37 +/- 0,04 s), and in the first peak vertical force during landing (p<0,05), with greater values in subjects with high-arch feet (C = 5,78 +/- 1,29 BW Y P = 4,29 +/- 0,84 BW). The other variables studied did not show significant differences between groups, although peak vertical force s for the maximum tests were greater in the high-arch feet group, and peak forces during walking and running were slightly greater for the flat feet group. The lack of significant differences does not have to be the limit to predict the risk of injury provoked by greater peak forces. Small and not significant differences might be enough to increase this risk. The higher force values found in the high-arch feet group during maximal tests show a higher risk of injury during these kinds of movements. The minimal differences found in the movement pattems between groups could be explained by individual adaptations during the tests


Assuntos
Feminino , Adolescente , Adulto , Humanos , Pé Chato/classificação , Pé Chato/epidemiologia , Pé Chato/fisiopatologia , Deformidades do Pé/fisiopatologia , Movimento/fisiologia , Fenômenos Biomecânicos/métodos , Cinética , Ferimentos e Lesões/prevenção & controle , Locomoção/fisiologia , Pé/fisiologia , Pé/fisiopatologia , Deformidades do Pé/classificação , Marcha/fisiologia , Movimento (Física) , Antropometria/métodos
10.
Psicológica (Valencia, Ed. impr.) ; 26(1): 61-79, ene.-jun. 2005. ilus, tab, graf
Artigo em Inglês | IBECS | ID: ibc-044017

RESUMO

Many studies have analysed how goal directed movements are corrected inresponse to changes in the properties of the target. However, only simplemovements to single targets have been used in those studies, so little isknown about movement corrections under more complex situations.Evidence from studies that ask for movements to several targets in sequencesuggests that whole sequences of movements are planned together. Planningrelated segments of a movement together makes it possible to optimise thewhole sequence, but it means that some parts are planned quite long inadvance, so that it is likely that they will have to be modified. In the presentstudy we examined how people respond to changes that occur while they aremoving to the first target of a sequence. Subjects moved a stylus across adigitising tablet. They moved from a specified starting point to two targetsin succession. The first of these targets was always at the same position butit could have one of two sizes. The second target could be in one of twodifferent positions and its size was different in each case. On some trials thefirst target changed size, and on some others the second target changed sizeand position, as soon as the subject started to move. When the size of thefirst target changed the subjects slowed down the first segment of theirmovements. Even the peak velocity, which was only about 150 ms after thechange in size, was lower. Beside this fast response to the change itself, thedwell time at the first target was also affected: its duration increased after thechange. Changing the size and position of the second target did not influencethe first segment of the movement, but also increased the dwell time. Thedwell time was much longer for a small target, irrespective of its initial size.If subjects knew in advance which target could change, they moved fasterthan if they did not know which could change. Taken together, these resultssuggest that the whole sequence is treated as one action, which can becorrected if the properties of any of the targets change. The precise nature andtiming of the correction depends on how the change influences the task


Assuntos
Humanos , Estudos de Tempo e Movimento , Movimento (Física) , Fenômenos Biomecânicos
11.
Psicológica (Valencia, Ed. impr.) ; 26(1): 105-119, ene.-jun. 2005. ilus, graf
Artigo em Inglês | IBECS | ID: ibc-044020

RESUMO

Dynamic Visual Acuity (DVA) can be measured from two types ofequivalently considered movement referred to as drifting-motion anddisplacement-motion. Displacement motion can be best described as thehorizontal displacement of a stimulus, thus implying pursuit eyemovements, and involves moving the stimulus from the fixation point ofgaze towards the periphery. The drifting motion of a Gabor patch, forexample, avoids pursuit eye movements, since the gaze is fixed in a point ofthe patch. Our data shows that in both types of movement visual acuity(VA), expressed in terms of spatial frequency, diminished as the velocity ofthe target increased. However, the slope of the regression equation indicatedthat this impairment is more than two-fold in the case of drifting-motionwhen compared to displacement motion. As the greater impairment tookplace when pursuit eye movements did not exist, our data suggests that thesetwo types of motions correct differently for retinal slip. Retinal slip appearsto be less efficiently compensated for in the case of drifting motion havingadverse consequences on VA, while retinal slip has a higher tolerance in thecase of displacement motion exhibited by the performance in VA


Assuntos
Humanos , Percepção Visual , Movimento (Física) , Acuidade Visual , Percepção Espacial , Comportamento Espacial
12.
Psicológica (Valencia, Ed. impr.) ; 26(1): 139-146, ene.-jun. 2005. tab, graf
Artigo em Inglês | IBECS | ID: ibc-044022

RESUMO

Different asymmetries between expansion and contraction (radial motions)have been reported in the literature. Often these patterns have been regardedas implying different channels for each type of radial direction (outwardversus inwards) operating at a higher level of visual motion processing. Intwo experiments (detection and discrimination tasks) we report reaction timeasymmetries between expansion and contraction. Power functions were fittedto the data. While an exponent of 0.5 accounted for the expansion databetter, a value of unity yielded the best fit for the contraction data. Instead ofinterpreting these differences as corresponding to different higher ordermotion detectors, we regard these findings as reflecting the fact thatexpansion and contraction tap two distinct psychophysical input channelsunderlying the processing of fast and slow velocities respectively


Assuntos
Humanos , Movimento (Física) , Estudos de Tempo e Movimento , Percepção Visual , Tempo de Reação
13.
Psicológica (Valencia, Ed. impr.) ; 26(1): 209-228, ene.-jun. 2005. ilus, graf
Artigo em Inglês | IBECS | ID: ibc-044027

RESUMO

If a moving stimulus (i.e., launcher) contacts a stationary target thatsubsequently begins to move, observers attribute motion of the target to thelauncher (Michotte, 1946/1963). In experiments reported here, a stationarylauncher adjacent to the target appeared or vanished and displacement inmemory for the position of the target was measured. Forward displacementof moving targets was less (a) when launchers appeared than when launchersvanished, and (b) when targets moved in the direction of implied impetusthan when targets moved in a direction orthogonal to implied impetus.Whether launchers appeared or vanished did not influence displacement oftargets that remained stationary. The data were consistent with thehypothesis that forward displacement of the target decreased when observersattributed target motion to an impetus resulting from gamma movement ofthe launcher that was imparted to the target. More generally, the data wereconsistent with an impetus-based explanation of Michotte’s launching effect(e.g., Hubbard & Ruppel, 2002), and suggest the apparent perception ofcausality is cognitively mediated rather than direct


Assuntos
Humanos , Movimento (Física) , Percepção de Movimento , Percepção Visual
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