Some Effects of Stimulus-Exposure Time on Choice-Reaction Time

Abstract

Eighty-six college students were run in two experiments investigating choice-reaction time as a function of mixed and constant exposure time. Within the range of exposure times explored (50-150 msec.), conditions employing a constant exposure time did not differ from one another. However, when a series of short exposure times was mixed with a series of intermediate exposure times, the reaction time to both was increased. The major conclusion is that stimulus and subject factors develop within the experimental situation to produce effects that cannot be predicted from knowledge of only the stimulus-exposure conditions. There have been a number of recent studies on the effects of stimulus-exposure time on reaction time. Raab and his associates have shown that simple reaction time became shorter with increasing exposure time, but only for brief exposures (up to about 20 msec.) and only at dim luminances (up to about 30 mL.)1 With more complex discrimination tasks, Kaswan and Young have shown that both accuracy and choice-reaction time were affected by a much wider range of exposure times (4-512 msec.). Accuracy increased with increasing exposure time at all luminance levels but was largely unaffected by variations in luminance (.0911.84 mL.). Choice-reaction time varied as a function of both luminance and exposure time; the relation of luminance and exposure time to choice-reaction time gradually shifted from direct at dim and brief exposures, to inverse at bright and long exposures.2 Various procedural problems can arise, however, when atReceived for publication January 5, 1970. This research was supported by Faculty Research Grant F-362 from the Bureau of General Research, Kansas State University. Special thanks must be given to David Strohm for assistance in the collection of data. Mr. Strohm was supported by the NSF Undergraduate Research Participation Program, Grant GY-13. 1D. Raab, E. Fehrer, and M. Hershenson, Visual reaction time and the Broca-Sulzer Phenomenon, J. exp. Psychol., 61, 1961, 193-199; D. Raab and E. Fehrer, The effect of stimulus duration and luminance on visual reaction time, J. exp. Psychol., 64, 1962, 326-327. 2J. Kaswan and S. Young, Stimulus exposure time, brightness, and spatial factors as determinants of visual perception, J. exp. Psychol., 65, 1963, 113123; J. Kaswan and S. Young, Effect of luminance, exposure duration, and task complexity on reaction time, J. exp. Psychol., 69, 1965, 393-400.