Context effect of common objects on visual processing.
In previous experiments on visual processing it was shown that correct identification of sequentially and simultaneously presented numerals declined as the presentation interval was decreased from 50.0 to 16.7 ms/numeral. To determine how performance was influenced in context, common everyday objects were used in place of the numerals. These objects were grouped into 36 different categories with 4 objects per category. An example of a category was fruit: apple, banana, pear, pineapple. For all experimental trials, objects (ranging in number from one to four) were presented randomly at four possible positions 1.5 degrees from a central fixation point. In a sequential trial, the objects were displayed in succession at different locations for a stimulus onset asynchrony (SOA) of either 16.7, 33.3, or 50.0 ms. The masking of a previous object coincided with the onset of the object that followed in the sequence. A simultaneous trial consisted of 2, 3, or 4 objects presented concurrently. For these trials, simultaneous masking occurred at SOA's of 16.7, 33.3, or 50.0 ms. For both experimental paradigms, one-half of the trials consisted of objects from the same category, and one-half from mixed categories. Results taken from four observers showed that performance for all three SOA's was consistently better when the objects were related as opposed to when the objects were not for both presentation protocols. This lent support to the theory that there was simultaneous interaction of top-down and bottom-up processes in visual processing. In addition, as was found in the numerals study, performance was better when the objects were presented simultaneously as opposed to sequentially.
Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, USA.
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D000328:Adult; D001288:Attention; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D010470:Perceptual Masking / Q000502:physiology; D014794:Visual Fields