Physical and cognitive dimensions in stimulus comparison

Abstract

Two experiments were carried out using a same-different task with sets of four stimuli varying orthogonally in three dimensions. Sameness was defined by each of the three dimensions in turn, as well as by physical identity. Two types of dimensions, physical and cognitive, were studied. In Experiment 1, the numerals 6, 10, VI, and X, which vary in Length, System, and Name, were used. With simultaneous presentation, order of difficulty was from the physical dimension of Length to the cognitive dimension of Name. While overall difficulty was related to dimensional discriminability, internal evidence suggested that Name was not a dimension in the same sense as Length is, and that some stimulus pairs were simply easier to process than others, regardless of the response required (e.g., short stimulus pairs and Arabic numerals). With sequential presentation, Name was processed as fast as System, due largely to the fact that much faster responding occurred when an Arabic numeral was the second stimulus. Thus, with sequential presentation, Name provides a processing mechanism not provided by physical dimensions. In Experiment 2, the numerals 3, 4, 6, and 7, which vary in Magnitude, Oddness, and Curvilinearity, were used. The cognitive dimension of Magnitude was processed most rapidly, and numerical distance between pairs of numbers dominated the results for "same" responses, regardless of the sameness rule used. Again, evidence was found for fast processing of some stimulus pairs (e.g., 3 4), regardless of the response required. Overall, these experiments are interpreted as indicating that cognitive factors such as stimulus familiarity may override as~ts of physical discriminability with many dimensions and stimuli, that, even though a cognitive dimension can be used to generate a logically proper set of stimuli, it does not necessarily act as other, more physical dimensions do, and that clarification of the functional role of a dimension is more important than attempts to locate stages.Stimulus comparison techniques such as the samedifferent task have been used quite commonly to establish levels or hierarchies of processing, starting with the Posner and Mitchell (1967) research, with more recent research well reviewed in Posner (1978). The most frequently used stimulus materials have been visual letters, with the rule for sameness varied to manipulate the presumptive level of processing. To illustrate, in the Posner and Mitchell (1967) experiments, upper-and lowercase letters were used,

Facilitation and interference with a separable redundant dimension in stimulus comparison

“…As Santee and Egeth (1980) noted, these results have been obtained with dimensions that have been shown to be separable from results from classification tasks. For different stimulus pairs, the results have been very inconsistent, ranging from an increase in RT with irrelevant disparity (e.g., Larsen & Bundesen, 1978), to a decrease in RT (e.g., Garner, Podgorny, & Frasca, 1982), to no effect or an inconsistent effect (e.g., Dixon & Just, 1978).…”

Nominal and physical decision criteria insame-different judgments

“…Gamer, Podgorny, and Frasca (1982) defined stimulus dimensions on a continuum from physical to cognitive, such that a pair to be compared could be defined as same on a physical versus a more arbitrary (learned) dimension. They found that when the sameness rule was cognitive, there was no fast-same effect (nonsignificant 1D-msec advantage for same stimuli in Experiment 1A and a nonsignificant 6-msec fast-different effect in Experiment 2).…”

Perceptual learning: An analysis based on selective attention measurements

“…Garner, Podgorny, and Frasca (1982) recently carried out a set of experiments to determine whether a stimulus name functions in the same way that physical attributes do. Although their research was not directly concerned with perceptual learning, we used their fmdings to study this problem in terms of the selective attention paradigm that has been used to study the interaction of various kinds of stimulus attributes (e.g., Garner, 1978;Garner & Felfoldy, 1970;Pomerantz & Garner, 1973).…”

“…The stimulus set used by Garner et al (1982) is useful for studying perceptual learning because it is described by physical and cognitive stimulus dimensions. A physical dimension is one on which the physical properties of the stimuli are adequate for carrying out a task, whereas a cognitive dimension is one on which the physical properties are insufficient to accomplish a task, so that the subject has to make his judgment using a learned association.…”

“…To examine the differences between physical and cognitive stimulus dimensions, Garner et al (1982) used the Roman and Arabic characters VI, 6, X, and /0, which differ on the attributes of length, system, and name. To adapt their work to the study of perceptual learning, we selected characters from the Roman and Hebrew alphabets, so that the name dimen-sion would be more familiar to one group of subjects than to the other.…”