THE VARIATION OF THE INTENSITY OF VISUAL SENSATION WITH THE DURATION OF THE STIMULUS
1904; Wiley; Volume: 1; Issue: 2 Linguagem: Inglês
10.1111/j.2044-8295.1904.tb00156.x
ISSN1747-3470
Autores Tópico(s)Academic and Historical Perspectives in Psychology
Resumo8 1. Review qf results o f other workers-the wide discrepancies between them-probable sources of error pointed out.0 2. Description of new method of determininy the action-time' o f light of a n y given intensity, i.e. the duration of its action upon the retina necessary f o r the production of sensation of maximum intenuity.8 3.The action-time of white l y h t varies, inversely with its intensity, f r o m about *2 to about -03 second. 4.When the duration of action of light is less than its wtion-time, the intensit;y of the sensation i s directly proportional to the duration qf the s t i m u h .This fact seems to suggest the true explanntion of the Talbot-Plateau law.9 5.The action-time of the nainimuin perceptible light is about -2 second.l'he bearing of this fact O ~L the principles of construction o f j a s h i n g coast-lights.8 6.Criticism of Kunkel's work on the action-times of coloured lights.H i s over-estimation of the action-times of green and blue lights, relatively to that of red light, probably due to neglect to eliminate the efects of excitation of the rod-apparatus.Red, green, and blue lights of equal intensities have action-times of equal or very nearly equal ohration.$ 1. Critical review of the methods and results of other observers.ON considering the phenomena of flicker and of fusion of rotating sectors, it seemed to me that in order to arrive a t a full understanding of them we must first ascertain the least time during which a light of given intensity must act upon the retina in order to produce 10-2 152 Intensity of Sensation and Duration of Stimulus its full effect in sensation, i.e. in order to excite the sensation of the highest intensity that it is at all capable of exciting.This time I propose for the sake of brevity to refer to hereafter as the ' action-time ' of the light-stimulus.It Reemed necessary also to ascertain what proportion of its full effect is produced by light of given intensity acting upon the retina during any period of time less than its action-time, i.e. during any fraction of its action-time.On referring to the textbooks I found that the accepted determinations were those of Prof. Exner' and Dr Kunkelz.Their methods and results seemed to ine to be open to serious objections, and I therefore began a series of determinations by a new method.When my preliminary experiments had been made, a paper was published by Prof. Gotz Martius3 in which he reported new determinations of the action-time, differing widely from my own and still more widely from those of Exner and Kunkel.Since I believed myself able to point out in the procedures of these observers sources of error that seem to account for the wide differences between their results, and that seem to be avoided in my own experiments, I continued the work and obtained the results recorded below.Two other researches dealing with this problem must be mentioned, one by W. Swan, formerly Professor of Natural Philosophy in the University of St Andrew's', the other by Prof. A. Charpentier.Swan's procedure would seem to have involved most of the principal sources of error that I have to point out in the procedures of Exner, Kunkel, and Martius, and it is not necessary to criticise it in detail because i t led to the conclusion that the action-time is the same for light of all intensities, namely about second, whereas Exner's, Martius' and my own researches, though differing widely as to the absolute duration of the action-time, are thoroughly concordant in showing that the action-time varies inversely with the intensity of the light, i.e. is shorter the more intense the light.Charpentier's experinients6 are so briefly reported that it is not possible t o criticise them in detail.He states that the action-time is about Q second, and (if I have not misinterpreted the 1 '' Ueber die zu einer Gesichtswahrnehmung nothige Zeit," Sitz.-Ber.d .Wiener Akad.
Referência(s)