Simultaneous motor and verbal processing of visual information in a modified Stroop test

Abstract

Color patches could simultaneously be manually counted and conflicting color words named in the time required for one of the tasks alone. The independence of verbal and nonverbal information processing resembles "split-brain" behavior. Naming color patches while counting color words took more time than would have been required for doing the individual tasks successively, indicating response competition in the standard Stroop test. Form or location stimuli substituted for color words reduced interference when naming color patches.Responding to two dimensions of a multidimensional task is generally difficult. Peterson (1969) has examined several tasks that required concurrent verbal processing, and suggested that, although training can reduce interference, simultaneous processing of material reduces the efficiency of either task. The S may not be able to attend simultaneously to two stimulus inputs (Broadbent, 1958;Treisman, 1969); "central processing capacity" may be used up by the tasks, leaving less capacity for each one individually (posner, Boies, Eichelrnan, & Taylor, 1969;Hammerton, 1969); or covert verbal responses to the task may conflict (Crovitz, Schiffman, & Rees, 1967). METHOD General ProcedureInterference in the simultaneous processing of different stimulus dimensions was examined using a modification of the Stroop color-word test (Jensen & Rohwer, 1966). The usual color-word test requires the S to scan and name the colors of several differently colored inks or patches. If the inks or patches include a conflicting color word (e.g., a red patch with the word "blu" on it), the interference decreases S's rate of naming the patch colors. In this study, only two values were used for each dimension, but S was required to respond simultaneously to both dimensions of a stimulus. For example, with the color-word stimuli, Ss had to read aloud the color words ("red" and "blu") and, at the same time, count the' number of red patches and the number of blue patches with two Veeder-Root hand tally counters, one hand for each of the two colors. SubjectsFour women and three men, the seven best performers of a group of 32 graduate and undergraduate students, were tested on simultaneously naming and counting the stimuli. The selection procedure allowed the study of maximum capacity rather than typical performance.·We thank Gary Hudson and Philip Frank for their assistance in collecting and analyzing the data. This work was supported by NASAGrants NGL 47-o06-o08-FF and NGR 47-006-028. Materials and ProcedureThe stimuli were 30 red and 30 blue patches of Dymo embossing tape. Each stimulus array was 6 rows of 10 patches in semirandom sequence. Two sets of each array were used, and the arrays were modified after each trial by either interchanging the rows within the array or by changing the array. Stimulus interference with patch color processing was manipulatetl by using two attributes from one of three other dimensions which were printed in white on the patch. These dimensions and their attributes were color words ("red...

Half a century of research on the Stroop effect: An integrative review.

“…Interference increased, but overall response rate also slowed down. Others also altered the standard color-word task (e.g., Dyer, 1973b;Friedman & Derks, 1973;Hall & Swane, 1973;Uleman & Reeves, 1971). Sometimes more than one of the dimensions have been combined, as in the case of the colordigit interference task devised by Wolitzky, Hofer, and Shapiro (1972).…”