Abstract
This tutorial article aims to guide the reader to learn about three types of psychophysical methods: the method of adjustment, the method of limits and the method of constant stimuli. The article explains how to estimate the point of subjective equality and the just noticeable difference with each method. It also explains about pitfalls that one may encounter when designing experiments. Results could be distorted by some bias effects that are due to technical procedures adopted for experiments. One should know where these effects are likely to occur.