Reaction times reveal the contribution of the different receptor components in luminance perception

Abstract

Pieron (1914, 1920,1952)demonstrated that simple reaction time decays as a hyperbolic function of luminance. Similarities between cell latencies and reaction time (RT) to luminance suggest that this relationship may be determined by retinal processes. Ifthe exponent of the Pieron function is specific to a given sensory modality, as assumed by some authors (e.g., Bonnet, 1992aBonnet, , 1992bNorwich, 1987), it should reflect receptor activities. Consequently, functions with different exponents should fit data for different luminance ranges. In a contrast-discrimination experiment, we investigated this question with a large range of luminance levels in a two-alternative spatial forced-choice task. The results of the experiment show that three functions with different exponents fit RTto the three luminance ranges (scotopic, mesopic, and photopic). The exponent decreases with increasing luminance. The findings indicate that the exponent and the asymptotic latency of the RT function reflect receptor activities of the visual system. Classically, data obtained in experiments relating reaction time (RT) to intensity are fitted to a single power function. Simple reaction time (SRT) decreases when the intensity of a given stimulus increases (see, e.g., Cattell, 1886;Exner, 1868;Pieron, 1914Pieron, , 1920Pieron, , 1952Wundt, 1886). The original equation for this function was introduced by Pieron (1914Pieron ( ,1920Pieron ( ,1952:where SRT is simple reaction time, to is the asymptotic RT reached at the highest stimulus intensities, f3 is a free parameter, I is the intensity of the stimulus, and a is the exponent of the function.Some authors have provided evidence that choice reaction time (CRT) also decreases when the luminance of the stimulus increases (e.g., Lappin & Dish, 1972;Pachella & Fisher, 1969;Posner, 1986). Moreover, Pins and Bonnet (1996) have shown that the Pieron function adequately describes the relationship between CRT and luminance and that the exponent of the function does not change with the complexity of the psychophysical task. In particular, it does not seem to matter whether the task is an SRT or a CRT task. Pieron functions would differ only by the constant to and the parameter f3.Thanks are due to J. C. Baird, L. M. Ward, and J. E. Cutting for their insightful comments and suggestions on an earlier version ofthis paper. Correspondence should be addressed to D. Pins, Laboratoire de Psychophysique Sensorielle (EP618, C.N.R.S.), Universite Louis Pasteur, 12 rue Goethe, F-67000, Strasbourg, France (e-mail: dpins@currifl.u-strasbg.fr).Similarities between measures ofcell latency and measures of RT to luminance have been reported. On the basis of a comparison of RT, alpha blocking latency, and the latency ofb-wave ofthe electroretinogram, Bernhard (1940) concluded that all three measures followed a similar function, differing only by an additive constant. Monnier (1949) reached the same conclusion by studying retinal time, retinocortical time, alpha blocking time, and motor RT. Later, using computer-averag...

The Piéron function in the threshold region

“…Complementarily, the fit of two functions was evaluated in calculating the sum of the squared residuals between the observed logit(p) and its theoretical value. This statistic (Id 2 ), which is more sensitive than the correlation coefficient, was minimal for the best fit of the two functions (e.g., Pins & Bonnet, 1997). The results are shown in Figure 1B.…”

“…Finally, to test the reliability ofthe present results in the upper range of intensities, we compared them with those obtained in a similar range in a previous experiment (Pins & Bonnet, 1997). The comparison is shown in Figure 3.…”

“…In order to compare the fit of a single function with the fit of two functions, we calculated the sum of the squared residuals of the observed RT and the function (Id 2 ) and used it as the criterion for the goodness offit (e.g., Pins & Bonnet, 1997). For the single func- …”

“…In this experiment, luminance levels covered the scotopic range, from a value just inferior to threshold to the beginning of the mesopic range (e.g., Pins & Bonnet, 1997). The target was presented in a spatial two-alternative forced-choice (2AFC) paradigm.…”

Componentes sensoriais e atencionais do tempo de reação: efeitos do tamanho, excentricidade e previsibilidade de estímulos visuais

“…Isso pode acontecer, por exemplo, quando o alvo visual ocorre em diferentes excentricidades ou quando o tempo de duração da apresentação do alvo é ampliado ou reduzido, refletindo processos relacionados à organização anátomo-funcional do sistema visual, como descrito anteriormente. Tal relação tem sido descrita em muitos trabalhos que investigam a influência, sobre o TR, de fatores tais como a intensidade (Cattel, 1886;Froeberg, 1907;Piéron, 1920Piéron, , 1952Rains, 1963;Pins & Bonnet, 1997), o tamanho (Osaka, 1976;Bonnet, Gurlekian, & Harris, 1992) e a localização de estímulos no campo visual (Osaka, 1982;Mancebo-Azor, Saez-Moreno, Dominguez-Hidalgo, Luna--Del Castillo, & Rodriguez-Ferrer, 2009;Carrasco, Evert, Chang, & Katz, 1995, Carrasco, Giordano, & McElree, 2006, além da participação de mecanismos atencionais (Posner, 1978;Tassinari & Berlucchi, 1995;Palmer, 1999;Liu, Stevens, & Carrasco, 2007).…”