ABSTRACT

Sensory thresholds are ill defined in theory (Lawless and Heymann, 1998; Morrison, 1982). A good determination requires hundreds of comparisons with a control, and results do not reproduce well (Brown et al., 1978; Marin et al., 1988; Stevens et al., 1988). Published group thresholds (Fazzalari, 1978; Van Gemert and Nettenbreijer, 1984; Devos et al., 1990) vary by a factor of 100 for quinine sulfate in water and by much more in complex systems. Swets (1964) doubts even the existence of a sensory threshold. A first reaction is that it is futile to invest time and money in threshold studies; however, in situations such as those described in the next paragraph, the threshold approach is still the best available.