Latencies to name one of three stimulus dimensions: A study of probability effects and dimension integrality

Abstract

Following each of 400 stimuli that varied according to three binary dimensions (location, color, and shape), subjects named the value of one particular dimension as quickly as possible. Each stimulus appeared on the "left" and "right" side of a screen (location dimension), and was a "red" or "green" triangle (color dimension) with apex oriented "up" or "down" (shape dimension). The alternatives of each dimension varied according to different probability distributions (90/10, 70130, or 50/50), and three schedule conditions were contrived so that each distribution occurred once for each dimension. Nine groups of 10 subjects each defined the factorial of 3 (response conditions: identify location, color, or shape) by 3 (schedule conditions: 90 left/70 red/50 down, 70 left/50 red/90 down, or 50 left/90 red/70 down). Latencies to identify the shape dimension were influenced reliably by the probabilities of both response-relevant and responseirrelevant stimuli. Shape probabilities did not affect latencies to identify location of color, but these latencies were significantly influenced by both color and location probabilities. Results are discussed with reference to the locus of the stimulus probability effect and dimensional integrality.Perhaps the most common finding when measuring latencies between stimulus presentations and identification responses is that choice reaction time (RT) is significantly shorter to more frequently occurring stimuli. The phenomenon has been termed a "stimulus probability effect" (SPE); and although the SPE has been consistently observed, interpretations of the cognitive locus of the phenomenon have not been consistent. Specifically, some RT investigators have claimed that the SPE is largely a responsebias effect, resulting from differential response selection (e.g., Theios, 1973Theios, , 1975, whereas others have presumed that variations in stimulus frequency affect primarily the stimulus-encoding stage of information processing (e.g., Pachella, 1974;Pachella & Miller, 1976). The present RT experiment was partially designed to study the relative importance of stimulus-encoding processes in determining the SPE.Three general techniques have been used to compare the relative influence of stimulus and response processing in determining the SPE: (1) threestimulus, two-response paradigms, (2) additivefactor designs, and (3) S-R compatibility manipulations. Although a given experiment has often showed Portions of this paper were presented at the Midwestern Psychological Association meeting, Chicago, 1975. Requests for reprints should be sent to E. Scott Geller, Department of Psychology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061. 70one information-processing component to be the more significant determinant of the SPE, the particular component judged to be the prominent factor has varied between experiments. For example, when RT was faster to the more probable of two stimuli identified with the same response, Bertleson and Tisseyre (1966) concluded that stimul...

Effects of task factors on selection by color in the rapid serial visual presentation (RSVP) task

“…For advance shape information (i.e., A or V), the same RT pattern was observed, but to a lesser degree. Similar benefits of advance color information have been reported for several different paradigms with stimuli appearing at multiple spatial locations (e.g., Carter, 1982;Geller, 1977;Green & Anderson, 1956;LaBerge & Brownston, 1974).…”

Case specificity of the stimulus probability effect

“…As noted earlier, several studies have reached the same conclusion on the basis of other experimental manipulations (e.g., . Geller, 1977;Miller & Pachella, 1973). The present studies are suggestive of rather specific mechanisms by which this effect may come about, however.…”

“…1. Geller (1977) reached a different conclusion about the effect of probability on feature detectors. He had subjects name the location, color, or shape of visually presented forms.…”

Flexibility of attention between stimulus dimensions

“…For instance, subjects may be able to attend optionally and exclusively between stimulus color and location only because these dimensions are separable (Garner, 1970(Garner, , 1974 or asymmetrically integral (i.e., they allow selective attention to color but not to location; cf. Garner, 1976;Geller, 1977). This may not be the case with integral stimulus dimensions, such as saturation and brightness (Garner & Felfoldy, 1970;Smith & Kemler, 1978).…”