Selective Perception and the Number of Alternatives

Visual vs. verbal stimulus set in a letter-classification task

“…All that mattered was whether or not the subject had time to make use of it. When functional and objective alternatives are equivalent, then restriction in number or alteration in probabilities of objective alternatives can have effects of their own (Long, Reid, & Henneman, 1960;Gummerman, 1971).…”

A model of selective perception: The effect of presenting alternatives before or after the stimulus

“…The 0 will be correct on (.735)(1.00) + (.088X.00) + (.1 76X.50) = .823 of the trials when m = 4; when m = 16, he will be correct on (.440)(1.00) + (.037)(.00) + (.518)(.50) = .699 of the trials. Comparing these two figures with the after data of can predict the after scores in Gummerman (1971) very nicely from the before scores. Presumably, this analysis would also be applicable to the data of Egeth & Smith (1967); however, these authors did not define the master set, M, for their Os, so it is not possible to make the calculations.…”

“…However, recent findings from a related type of study are not in agreement so a second int~rt:Jretation ~f before/~fter data is developed here.ThIS mterpretatlOn, based 10 part on a statistical decision mode~ taken from signal detection theory, assumes that selective perception functions by guiding the perceptual process of comparing extracted stimulus information with internal representations of stimulus alternatives Recent studies using Lawrence & Coles's (1954) before/after method have provided data that can be interpreted in terms of selective perceptual processing of brief visual stimuli (Egeth & Smith, 1967;Gummerman, 1971). This method may be briefly characterized as follows.…”

“…The observers in the After conditions could not know what kind of information to extract first; they got what they could from the flash, but there was an excellent probability that ... it would not be adequate for discrimination {po 549]." Similarly, Gummerman (1971) found a before vs after difference, with s = 2 and m = 16, and concluded that selective perception "appears to consist of 'instructions' as to which of the stimulus attributes are relevant and should he processed [po 177] ." In this latter study, no before enhancement occurred in a second condition, with s = 2 and m = 4.…”

Image generation in a letter-classification task

“…It must show not only that generation has time to occur with long onset asynchronies, but also that it does not have time to occur when onset asynchronies are too brief. Although several studies using accuracy measures of performance in marginal viewing conditions have obtained results compatible with an imagegeneration process (Egeth· & Smith, 1967;Gummerman, 1971;Long, Reid, & Henneman, 1960;Taylor & Reilly, 1970), few have examined both short and long onset asynchronies. Herzog (1976) looked at an "immediate" and a "delayed" condition, but his onset asynchronies were not precisely controlled.…”