RESUMO
A percepção visual depende do arcabouço sensorial e do processamento atencional. Este trabalho estudou o efeito, sobre o tempo de reação manual (TR), do tamanho, excentricidade e previsibilidade de estímulos visuais. No experimento 1 (n=8), um alvo foi apresentado aleatoriamente em uma de quatro excentricidades diferentes, possuindo três possíveis tamanhos. O experimento 2 (n=12) apresentava configuração similar, porém uma pista indicava o quadrante de maior probabilidade (70%) de apresentação do alvo. Os resultados mostraram um aumento do TR em função da excentricidade do alvo, além de uma diminuição do TR com o aumento do tamanho do alvo e indicação correta da pista. Uma análise das interações sugere uma superposição de mecanismos atencionais e puramente sensoriais compartilhando um estágio comum do processamento visual.
Visual perception depends on the sensory framework and on attentional processing. This study examined the effects of the size, eccentricity and predictability of a visual stimulus on manual reaction time (RT). In experiment 1 (n=8), a target was presented randomly in one of four different eccentricities, with three possible sizes. Experiment 2 (n=12) had a similar configuration but a cue indicated the higher predictability (70%) of target presentation quadrant. The results showed an increase in RT as a function of target eccentricity, and a decrease in RT with increasing target size or accuracy of the cue. An analysis of interaction effects suggests an overlay of attentional and purely sensory mechanisms sharing common stages of visual processing.
Assuntos
Humanos , Masculino , Feminino , Adulto , Atenção , Psicologia Experimental , Tempo de ReaçãoRESUMO
A percepção visual depende do arcabouço sensorial e do processamento atencional. Este trabalho estudou o efeito, sobre o tempo de reação manual (TR), do tamanho, excentricidade e previsibilidade de estímulos visuais. No experimento 1 (n=8), um alvo foi apresentado aleatoriamente em uma de quatro excentricidades diferentes, possuindo três possíveis tamanhos. O experimento 2 (n=12) apresentava configuração similar, porém uma pista indicava o quadrante de maior probabilidade (70%) de apresentação do alvo. Os resultados mostraram um aumento do TR em função da excentricidade do alvo, além de uma diminuição do TR com o aumento do tamanho do alvo e indicação correta da pista. Uma análise das interações sugere uma superposição de mecanismos atencionais e puramente sensoriais compartilhando um estágio comum do processamento visual.(AU)
Visual perception depends on the sensory framework and on attentional processing. This study examined the effects of the size, eccentricity and predictability of a visual stimulus on manual reaction time (RT). In experiment 1 (n=8), a target was presented randomly in one of four different eccentricities, with three possible sizes. Experiment 2 (n=12) had a similar configuration but a cue indicated the higher predictability (70%) of target presentation quadrant. The results showed an increase in RT as a function of target eccentricity, and a decrease in RT with increasing target size or accuracy of the cue. An analysis of interaction effects suggests an overlay of attentional and purely sensory mechanisms sharing common stages of visual processing.(AU)
Assuntos
Humanos , Masculino , Feminino , Adulto , Atenção , Psicologia Experimental , Tempo de ReaçãoRESUMO
The influence of visual stimuli intensity on manual reaction time (RT) was investigated under two different attentional settings: high (Experiment 1) and low (Experiment 2) stimulus location predictability. These two experiments were also run under both binocular and monocular viewing conditions. We observed that RT decreased as stimulus intensity increased. It also decreased as the viewing condition was changed from monocular to binocular as well as the location predictability shifted from low to high. A significant interaction was found between stimulus intensity and viewing condition, but no interaction was observed between neither of these factors and location predictability. These findings support the idea that the stimulus intensity effect arises from purely sensory, pre-attentive mechanisms rather than deriving from more efficient attentional capture.
Assuntos
Atenção/fisiologia , Tempo de Reação/fisiologia , Adulto , Humanos , Estimulação Luminosa , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Adulto JovemRESUMO
The world we perceive is delayed in relation to its flowing content, as well as the outcome of our actions on the world in relation to the moment we decide to act. This mosaic of different latencies permeating both perception and action has to be taken into account critically in order for us to cope with the temporal challenges constantly imposed by the environment. Fundamental notions, such as the sense of agency and causality, depend on the temporal relationship of events occurring in well-defined windows of time. Here, we offer a broad, yet abridged, historical view of some thought-provoking issues concerning the time of perception and action. From the pioneering work of Wundt, Titchener, and Libet to recent findings and ideas related to the employment of visual illusions as psychophysical probes (such as the flash-lag effect), we have tried to expose some problems inherent to the act of measuring the time of both perception and action, and devise possible solutions as well.
Assuntos
Percepção , Meio Ambiente , Humanos , Intenção , Fatores de TempoRESUMO
A percepçäo é a construçäo ativa de um estado neural que se correlaciona a elementos biologicamente relevantes do ambiente. Esta correlaçäo, longe de estabelecer uma representaçäo fiel do mundo, guia nossas açöes na elaboraçäo de comportamentos adaptativos, sendo, portanto, condicionada por fatores evolutivos. Já que a construçäo de um percepto é um processo intrinsecamente ambíguo, discrepâncias perceptivas podem surgir a partir de condiçöes idênticas de estimulaçäo. Essas discrepâncias säo denominadas ilusöes, e se originam dos mesmos mecanismos fisiológicos que produzem a nossa percepçäo cotidiana. Derivando de diferentes fatores, tais como ópticos, sensoriais e cognitivos, as ilusöes visuais säo instrumentos úteis na exploraçäo das bases fisiológicas da percepçäo e de sua interaçäo com o planejamento e execuçäo de açöes motoras. Aqui, examinamos as origens biológicas das ilusöes visuais e algumas de suas relaçöes com aspectos neurobiológicos, filosóficos e estéticos
Assuntos
Humanos , Ilusões Ópticas/fisiologia , Percepção/fisiologia , Arte , FilosofiaRESUMO
Perception is the active construction of a neural state that correlates with biologically relevant elements present in the environment. This correlation, far from affording a one-to-one mapping, nonetheless guides our actions towards adaptive behaviors, thus being forged under evolutionary constraints. Since the construction of a percept is an intrinsically ambiguous process, perceptual discrepancies can arise from identical stimulation patterns. The recognition of these discrepancies is termed illusion, which originates, however, from the same physiological mechanisms that ordinarily lead to standard perception. Emanating from different sources, such as optical, sensory and cognitive factors, visual illusions are useful tools in accessing the physiological basis of perceptual processes and their interaction with motor planning and execution. Here we examine the biological roots of visual illusions and their interplay with some neurobiological, philosophical and esthetical issues.