What is the difference between webers law and fechners law

Present a stimulus, have participants give the stimulus a number that they they indicates the sensory strength of the that stimulus. Modulus: In some versions, a standard stimulus is used, call the modulus. This stimulus is given a standard number, whatever the researcher wants, say Then the participant assigns numbers to the other stimulus that takes the modulus into account.

For example, if the participant thinks the stimulus just presented is twice as strong as the modulus and the modulus is 50 then the subject should give the stimulus a More in Chapter 2 of the text. What is a scientific law? So when you are in a noisy environment you must shout to be heard while a whisper works in a quiet room. And when you measure increment thresholds on various intensity backgrounds, the thresholds increase in proportion to the background.

Below is a plot of some hypothetical data showing Weber's Law. The slope of the line is the Weber fraction. A TVI plot. Threshold Versus Intensity sometimes called a TVR plot for thresholds for detecting light threshold versus radiance. Weber's Law is not always true, but it is good as a baseline to compare performance and as a rule-of-thumb.

On a plot of log I vs log I, the slope of the resulting line is one if Weber's Law holds. A modified version of Weber's law is as follows:. Here is real data from Aguilar and Stiles plotting increment thresholds. Each curve plots the same data in a different way using the two y-axes. See if you can interpret the data? Where is Weber's law approximately true? Continue on to Fechner's Law.