Two experiments were conducted in which simple auditory and simple visual reaction times (RTs) were compared on the same scale by presenting psychophysically equivalent response signals. In Exp. I, mean RT for both auditory and visual signals at 90 db. and 60 db. was the same; for the 30-db. comparison, RT was longer for the visual than for the auditory signal. Exp. II indicated that the light-tone difference at 30 db. was attributable to latency differences between reception at photopic and scotopic visual levels. In view of these results, the common assumption that auditory RT is shorter than visual RT was reconsidered.

It is widely assumed, based on Chocholle's (1940) research, that stimuli that appear equal in loudness will generate the same reaction times. In Experiment 1, we first obtained equal-loudness functions for five stimulus frequencies at four different intensity levels. It was found that equal loudness produced equal RT a~80 phons and 60 phons, but not at 40 phons and 20 phons. It is likely that Chocholle obtained equivalence between loudness and RT at all intensity levels because of relay-click transients in his RT signals. One main conclusion drawn from Experiment 1 is that signal detection (in reaction time) and stimulus discrimination (in loudness estimation) require different perceptual processes. In the second phase of this investigation, the RT-intensity functions from six different experiments were used to generate scales of auditory intensity. Our analyses indicate that when the nonsensory or "residual" component is removed from auditory RT measures, the remaining sensory-detection component is inversely related to sound pressure according to a power function whose exponent is about -.3. The absolute value of this exponent is the same as the .3 exponent for loudness when interval-scaling procedures are used, and is one-half the size of the .6 exponent which is commonly assumed for loudness scaling.The historic traditions that underlie the present research are formidable. Psychophysicists have consistently found a direct relation between auditory stimulus intensity and loudness. Specifically, Stevens and his colleagues have established that perceived loudness grows as a power function of stimulus intensity (Marks, 1974(Marks, , 1979. Equally impressive is the evidence in support of an inverse relation between stimulus intensity and simple auditory reaction time (RT). Classic experiments by Cattell (1886), Chocholle (1940), Pieron (1920), and Wundt (1874) have convincingly shown that RT decreases monotonically with corresponding increases in auditory stimulus intensity.Based on the fact that stimulus frequency, along with stimulus intensity, are the primary determinants of both loudness and RT, the present paper comprises two major sections in which these two stimulus attributes are evaluated. First, we evaluated the relation between equal loudness (across frequencies) and RT, using Chocholle's (1940) attempted to synthesize the data from several RT experiments in order to construct a uniform scale of sensory intensity that is based on RT measures. PHASE 1: EQUAL LOUDNESS AND REACTION TIMEIt is remarkable how many investigators have cited Chocholle's research, conducted over 40 years ago at the Sorbonne Laboratory, as the definitive study of the relation between auditory RT and signal intensity and frequency. His experiments were extensive but simple in design. Three experienced subjects generated RT-intensity functions over a wide range of intensity levels for frequencies of 20, 50, 250, 500, 1,000, 2,000, 4,000, 6,000, and 10,000 Hz. From these initial results, he drew "equal-RT" contours; that is, stimul...

Simple reaction time (RT) was investigated within the framework of adaptation level (AL) and stimulus intensity effects. Ss were preadapted to various levels of tonal intensity or to equally loud noise signals and given a reaction test series of tones immediately afterward. The persistence of AL effects over time was tested by giving i of the Ss the test series again 24 hr. later. The results were consistent with AL theory in that RT was a function of both stimulus intensity and the prevailing AL. Other results indicated that: (a) exposure to silence did not establish an effective preadaptation level, (b) the effects of preadaptation persisted for at least 24 hr., and (c) preadaptation to tone produced larger AL effects than did preadaptation to white noise.

The effects of auditory (Exp. I) and visual (Exp. II) ready signal intensity were investigated in a simple reaction time (RT) task. Mean RT to three auditory response signals was found to systematically increase with a corresponding increase in the intensity of either auditory or visual ready signals. The results were analyzed according to a decision model of stimulus intensity effects. It was concluded that ready signal intensity influenced the value of the detection criterion. Practice effects and individual differences were also significant determinants of the criterion level.

Equal-loudness contours were first obtained for five stimulus frequencies at four stimulus intensities. These 20 stimuli were then presented as reaction-time signals in a Donders C paradigm. The Z.transform method of convolution, as applied in linear systems identification, was used to deconvolve an empirically generated response (or "residual") distribution (T'R) from each of the 20 reaction-time (RT) distributions obtained at different intensities and frequencies. The resulting sensory-detection (tel) models formed exponential densities at strong intensities (60 and 80 phons), but their shapes were either gamma or normal at relatively weak intensities (20 and 40 phons). Our analyses support the idea that the simple reactiontime process (RT) is a convolution (or sum) of two component stages: stimulus detection (tell, followed by response evocation (tr). Based on the shapes of td, a neural-impulse theory is offered to account for the detection of simple auditory RT signals.In two previous papers (Kohfeld, Santee, & Wallace, 1981;Santee& Kohfeld, 1977), we reported that equally loud stimuli across five frequencies produced equal reaction times at 80-and 6O-phon intensities, but at the 40 and 20-phon levels the latencies were longer at 1,000 Hz than at the higher and lower stimulus frequencies. In order to provide a rigorous evaluation of these results, our present intent is to analyze the observed RT distributions generated from 100-, 500-, 1,000-,5,000-, and lO,OOO-Hz signals at intensities of 20, 40, 60, and 80 phons. Any dissimilarities among the shapes of these RT distributions, especially at the 20-and 4O-phon levels, should provide some insights as to whether the components of the RT process are different across stimulus frequencies when equivalently weak signals are employed.One basic premise in this paper is that signal detection and response initiation are the two component stages in the simple reaction time (RT) process. This notion is not new, as Green and Luce (1971), Hohle (1965), and McGill (1963 the RT process which begin with the assumption that observed RT distributions represent a convolution of the densities of two component random variables, one of which reflects the detection, or decision process (ld), and the other having to do with the response or "residual" latency (t r ) . The forms of these component densities have been open to controversy; for example, McGill (1963) assumed that td is normally distributed and t r is exponentially distributed, whereas Hohle (1965) argued for the exact opposite interpretation. More recently, Green and Luce (1971) attempted to find the shape of t r by constructing td theoretically (based on a Poisson pulse model of sensory detection), and then deconvolving ld from the empirical RT distribution. Although somewhat successful, Green and Luce were unable to identify a completely realistic model of t r , thus leading them to conclude that their initial model of ld would require further revision.In view of the difficulties encountered by Green and Luce in t...