The Weber-Fechner law is the most important discovery in the field of psychophysics, which allows us to characterize what seems to be incapable of yielding to any kind of characterization, namely, the sensation of man.
The basic psychophysical law of Weber-Fechner
First of all, let us consider the most important components of this expression. The Weber-Fechner law states that the intensity of a person's sensation is proportional to the logarithm of stimulus intensity. Needless to say, from the first time such a formulation of the Weber-Fechner law sounds frightening, but in fact, everything is quite simple.
Back in the 19th century, the scientist E. Weber was able to show with the help of several experiments that each new stimulus, so that a person could perceive it as different from the previous one, should have a difference with the previous variant by an amount proportional to the initial stimulus.
As a simple example of this statement, you can bring any two subjects that have a certain mass. To a person could perceive them as different in weight, the second should be different by 1/30.
Another example can be given on illumination. For a person to see the difference in the light of two chandeliers, their brightness should differ by 1/100. That is, a chandelier of 12 light bulbs will differ slightly from the one to which only one has been added, and a chandelier from one lamp, to which one has been added, will give significantly more light. In spite of the fact that only one bulb is added in both cases, the difference in illumination will be perceived differently, since it is the ratio of the initial stimuli and the one that is the next that is important.
The Weber-Fechner law: formula
The formulation that we discussed above is supported by a special formula that expresses the action of the Weber-Fechner psychophysical law. In 1860, Fechner was able to formulate a law that says that the sensation force p is proportional to the logarithm of the stimulus intensity S:
p = k * log {S} \ {S_0}
where S_0 is the value reflecting the intensity of the stimulus: if S
To understand this law, the concept of the so-called threshold, established in the process of psychophysical studies, is especially important.
Thresholds of the Weber-Fechner law sensations
Subsequently, it was found that the existing intensity of irritation required the achievement of a certain level, so that a person had the opportunity to feel its effect. Such a weak effect, which gives a barely perceptible sensation, is called the lower threshold of sensation.
There is also such level of influence, after which the sensations are no longer able to increase. In this case, we are talking about the upper threshold of sensation. Any kind of influence a person feels exclusively and the interval between these two indicators, which due to this is called external thresholds of sensation.
One can not help saying that there is no parallelism in the full sense of the word between the intensity of sensation and irritation and to be
In this case, we are talking about the fact that the increase in irritation is too weak. The amount by which the stimulation increases is called the discrimination threshold. Hence it follows that an irritation with too little distinctive intensity is pre-threshold, and with too strong a supramarginal. At the same time, the level of these indicators depends on the sensitivity with respect to the discrimination - if the sensitivity to discrimination is higher, then the discrimination threshold, respectively, is lower.