ABSTRACT
The units of quality used throughout this work are just noticeable differences (JNDs), the merits of which are discussed in some detail in subsequent chapters. To define and interpret JNDs, an underlying model of perception that is probabilistic in nature is required. In this chapter, a very simple model of this type is presented in Sect. 2.2. Properties of the normal distribution and definitions of probability density functions (PDFs) and cumulative distribution functions (CDFs) are given in Sect. 2.3. This permits the outcome of paired comparison experiments to be related to perceptual distribution properties in Sect. 2.4. Finally, in Sect. 2.5, the properties of the angular distribution, a convenient alternative to the normal distribution, are reviewed.
