RESUMO
Visual illusions have been studied in many non-human species, spanning a wide range of biological and methodological variables. While early reviews have proved useful in providing an overview of the field, they have not been accompanied by quantitative analysis to systematically evaluate the contribution of biological and methodological moderators on the proportion of illusory choice. In the current meta-analytical study, we confirm that geometrical visual illusion perception is a general phenomenon among non-human animals. Additionally, we found that studies testing birds report stronger illusion perception compared to other classes, as do those on animals with lateral-positioned eyes compared to animals with forward-facing eyes. In terms of methodological choices, we found a positive correlation between the number of trials during training or testing and the effect sizes, while studies with larger samples report smaller effect sizes. Despite studies that trained animals with artificial stimuli showing larger effect sizes compared with those using spontaneous testing with naturalistic stimuli, like food, we found more recent studies prefer spontaneous choice over training. We discuss the challenges and bottlenecks in this area of study, which, if addressed, could lead to more successful advances in the future.
Assuntos
Percepção Visual , Animais , Ilusões Ópticas/fisiologia , Ilusões , Aves/fisiologiaRESUMO
Static figurative images implying human body movements observed for shorter and longer durations affect the perception of time. This study examined whether images of static geometric shapes would affect the perception of time. Undergraduate participants observed two Optical Art paintings by Bridget Riley for 9 or 36 s (group G9 and G36, respectively). Paintings implying different intensities of movement (2.0 and 6.0 point stimuli) were randomly presented. The prospective paradigm in the reproduction method was used to record time estimations. Data analysis did not show time distortions in the G9 group. In the G36 group the paintings were differently perceived: that for the 2.0 point one are estimated to be shorter than that for the 6.0 point one. Also for G36, the 2.0 point painting was underestimated in comparison with the actual time of exposure. Motion illusions in static images affected time estimation according to the attention given to the complexity of movement by the observer, probably leading to changes in the storage velocity of internal clock pulses.
Assuntos
Percepção de Movimento/fisiologia , Ilusões Ópticas/fisiologia , Pinturas/psicologia , Estimulação Luminosa/métodos , Percepção do Tempo/fisiologia , Adulto , Análise de Variância , Atenção/fisiologia , Brasil , Feminino , Humanos , Masculino , Estudantes/psicologia , Fatores de Tempo , Adulto JovemRESUMO
The perceptual deficit hypothesis for schizophrenia is based on more general models of normal human visual perception, which have traditionally postulated that objects must compete for attention and processing space in the visual system. Recent evidence suggests that susceptibility of schizophrenics to the Müller-Lyer (ML) illusion may be a marker of vulnerability, detectable in prodromic patients, but disappearing with the progression of the illness. This illusion consists of overestimating the length of a straight line with converging arrowheads at the ends, while underestimating those with diverging arrowheads. Although the ML illusion has been shown to occur in touch as well as vision, it is not known whether abnormal contextual suppression extends to other sensory modalities in schizophrenics. Another challenge consists in verifying whether different visual parameters of the illusion which favor the magnocellular and parvocellular systems would have diverse ML illusion effects in schizophrenia. In this review we present data showing the degree of illusion in capuchin monkeys (Cebus spp.), a possible animal model for schizophrenia. To this end, a computer program was developed to conduct experiments in humans and non-human primates, allowing the display of illusory figures, manipulation of the stimuli's exposure time, interval between stimuli and number of trials. In the non-primate experiments, the visual illusion test based on achromatic ML illusion figures indicated the presence of the ML illusory effect in 10 capuchin monkeys. These results suggest that Cebus might be a good model for the experimental study of schizophrenia.
Assuntos
Ilusões Ópticas/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Esquizofrenia/diagnóstico , Esquizofrenia/fisiopatologia , Animais , Humanos , Esquizofrenia/patologiaRESUMO
Several accounts put forth to explain the flash-lag effect (FLE) rely mainly on either spatial or temporal mechanisms. Here we investigated the relationship between these mechanisms by psychophysical and theoretical approaches. In a first experiment we assessed the magnitudes of the FLE and temporal-order judgments performed under identical visual stimulation. The results were interpreted by means of simulations of an artificial neural network, that was also employed to make predictions concerning the FLE. The model predicted that a spatio-temporal mislocalisation would emerge from two, continuous and abrupt-onset, moving stimuli. Additionally, a straightforward prediction of the model revealed that the magnitude of this mislocalisation should be task-dependent, increasing when the use of the abrupt-onset moving stimulus switches from a temporal marker only to both temporal and spatial markers. Our findings confirmed the model's predictions and point to an indissoluble interplay between spatial facilitation and processing delays in the FLE.
Assuntos
Percepção de Movimento/fisiologia , Ilusões Ópticas/fisiologia , Percepção do Tempo/fisiologia , Adolescente , Adulto , Humanos , Modelos Psicológicos , Redes Neurais de Computação , Estimulação Luminosa/métodos , Psicometria , Psicofísica , Tempo de Reação/fisiologia , Adulto JovemRESUMO
We measured human frequency response functions for eleven angular frequency filters using a forced-choice procedure in a supra-threshold summation paradigm. Each of the eleven functions of 17 experimental conditions was measured 4-9 times among 12 observers. Results show that, for the arbitrarily selected filter phases, maximum summation effect occurred at test frequency for all filters. These results lead to the conclusion that there are narrow-band angular frequency filters operating in human visual system mostly through summation surrounded by inhibition at the specific test frequency ranges. Our previous suggestion (Simas and Santos, 2002), arguing that summation for the higher angular frequency filters should occur if background angular frequency contrast were set to a maximum of 5 times the test frequency threshold, was supported.
Assuntos
Sensibilidades de Contraste/fisiologia , Filtração/instrumentação , Retina/fisiologia , Visão Ocular/fisiologia , Córtex Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Inibição Neural/fisiologia , Ilusões Ópticas/fisiologia , Orientação/fisiologia , Psicofísica , Limiar Sensorial/fisiologia , Vias Visuais/fisiologiaRESUMO
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.
Assuntos
Percepção de Forma/fisiologia , Ilusões Ópticas/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Córtex Visual/fisiologia , Humanos , PsicofísicaRESUMO
In visual science the term filling-in is used in different ways, which often leads to confusion. This target article presents a taxonomy of perceptual completion phenomena to organize and clarify theoretical and empirical discussion. Examples of boundary completion (illusory contours) and featural completion (color, brightness, motion, texture, and depth) are examined, and single-cell studies relevant to filling-in are reviewed and assessed. Filling-in issues must be understood in relation to theoretical issues about neural-perceptual isomorphism and linking propositions. Six main conclusions are drawn: (1) visual filling-in comprises a multitude of different perceptual completion phenomena; (2) certain forms of visual completion seem to involve spatially propagating neural activity (neural filling-in) and so, contrary to Dennett's (1991; 1992) recent discussion of filling-in, cannot be described as results of the brain's "ignoring an absence" or "jumping to a conclusion"; (3) in certain cases perceptual completion seems to have measurable effects that depend on neural signals representing a presence rather than ignoring an absence; (4) neural filling-in does not imply either "analytic isomorphism" or "Cartesian materialism," and thus the notion of the bridge locus--a particular neural stage that forms the immediate substrate of perceptual experience--is problematic and should be abandoned; (5) to reject the representational conception of vision in favor of an "enactive" or "animate" conception reduces the importance of filling-in as a theoretical category in the explanation of vision; and (6) the evaluation of perceptual content should not be determined by "subpersonal" considerations about internal processing, but rather by considerations about the task of vision at the level of the animal or person interacting with the world.
Assuntos
Ilusões Ópticas/fisiologia , Percepção Visual/fisiologia , Humanos , Psicofísica , Fatores de Tempo , Visão Ocular/fisiologia , Córtex Visual/fisiologiaRESUMO
Mach bands are illusory bright and dark bands seen where a luminance plateau meets a ramp, as in half-shadows or penumbras. A tremendous amount of work has been devoted to studying the psychophysics and the potential underlying neural circuitry concerning this phenomenon. A number of theoretical models also have been proposed, originating in the seminal studies of Mach himself. The present article reviews the main experimental findings after 1965 and the main recent theories of early vision that have attempted to account for the effect. It is shown that the different theories share working principles and can be grouped into three classes: (a) feature-based; (b) rule-based; and (c) filling-in. In order to evaluate individual proposals, it is necessary to consider them in the larger picture of visual science and to determine how they contribute to the understanding of vision in general.