O fenÃmeno muitas faces: estudo comparando a percepÃÃo do fenÃmeno quando utilizados estÃmulos de face e cadeira

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The Multiple Faces Phenomenon, is perceived when printed faces are observed at the visual peripheral field. This phenomenon is characterized by perception of changes in the face, such as, movements and variations of facial expression (category 1), and new characteristics or perception of other faces with different identities (category 2). The current study compared the Phenomenon when a face and a chair images were used as stimulus. Sixty healthy volunteers (30 men and 30 women), aged 18 to 30 years old participated in the experiments. They were instructed to stare, monocularly, at the dot placed on the right or the left sides of the face-stimulus. In this way, the image of the face was centered into the subjectÂs blind spot. They had to press 1 to movements and expression changes and 2 for the appearance of new characteristics or other faces perception. The results were analyzed using an ANOVA for repeated measurements and the Newman-Keuls post hoc test. They indicated higher incidence of the phenomenon when face stimulus was presented to each eye (p= 0.001 to the right and p= 0.005 to the lefth), mainly for category 2 (p= 0.0001 with the right eye and p= 0.0004 with left one). We concluded that the phenomenon is not restricted to faces, but may occur with another visual object (chair). The higher frequency noticed for faces may be related to human specialization for identification and recognition of this visual objects. We believe that when an object is adapted at the visual peripheral field, specialized areas may engender this âtop-downâ effect. A pilot study (with one male adult volunteer) using the Functional Magnetic Resonance Imaging (fMRI) was performed to observe the related cortical areas concerning this phenomenon. Enhancement of activity at the fusiform gyrus was observed when the face as-stimulus was shown at the peripheral field and the module of stimulation was once repeated. We suppose that by adapting faces at the peripheral visual field, cortical specialized areas activation are sustained during the Multiple Faces perception

ASSUNTO(S)

percepÃÃo de faces neurologia multiple faces phenomenon perceptive processes processos perceptivos psicofÃsica psychophysics object perception fenÃmeno muitas faces percepÃÃo de objetos face perception

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