Perceptibility gradients for tachistoscopic patterns: Sensitivity or saliency?

Abstract

College of William and MaryThree lines of evidence are offered against the proposition of Hershenson that so-called "perceptual reports" of tachistoscopic patterns are determined by retinal sensitivity. First, perceptual reports are not determined by absolute (retinal) position of stimulus elements. Second, best performance for elements nearer fixation can be obtained from conventional tasks in which "postperceptual" factors are obviously effective. Third, results of a mock perceptual-report experiment, in which subjects merely guessed which stimulus elements would be seen, duplicated Hershenson's results. This evidence favors intrinsic organizational processes as a determinant of perceptibility for elements within tachistoscopic patterns.Differences in perceptibility of elements within tachistoscopic patterns have been attributed to active organizational mechanisms of memory and response evocation (e.g.

Information extraction from different retinal locations.

“…Both Harcum (1964) and Hershenson (1969) would predict this to be the case-both accuracy and reaction time data should reflect one another. These data do not directly converge on the notion of sensitivity compared with saliency as put forth by Harcum (1970). They do provide data that can be used to estimate the effects of manipulating fixation in other reaction time tasks that have spread letters across a fixation point.…”

“…Hershenson (1969) has challenged this argument, suggesting that under circumstances in which the perceiver is thoroughly familiar with the organization of the material, the distance from fixation determines perceptual clarity and accuracy of report. Harcum (1970), after reanalyzing Hershenson's data, has not been convinced, and the issue is as yet unresolved.…”

Individual differences in adult foveal visual asymmetries.

“…The most widely held explanation of the origin of end asymmetries is that they are the result of sequential processing of visual information (Braine, 1972;Bryden, 1967;Harcum, 1970). That is, the elements of a stimulus are said to be processed serially in a given order and those elements processed first have a perceptual advantage over those processed later.…”

Developmental changes in foveal tachistoscopic recognition between prereading and reading children.

“…metries in recognition is that they are the result of a left-to-right and top-to-bottom sequential processing mechanism which develops along with and obtains its direction from reading-scan habits (Bryden, 1967;Harcum, 1967Harcum, , 1970Heron, 1957;Lefton, 1974), Confirmation and understanding of this sequential processing mechanism would add greatly to our knowledge of directional behaviors such as reading, overt scanning patterns, and general perceptual organization. However, there is more than one possible explanation for recognition asymmetries, and the asymmetries themselves are inconclusive evidence for a sequential processing mechanism because they may reflect the effects of order of report, rehearsal strategies, and fixation errors (Ayers, 1966;Hershenson, 1969;McKeever, 1974;McKeever & Huling, 1970Miller, 1971Miller, , 1972Smith & Ramunas, 1971).…”