ABSTRACT
Psychophysics is a science concerned with the measurement and evaluation of stimulus-response relations by means of human behavior. Stimuli are measured by chemical or physical methods, while the sensations are evaluated by psychophysical techniques. Although psychophysical methods can be applied to all senses, relevant information concerning the sensory properties of foods are mainly related to chemical senses such as smell and taste. Sensory evaluations of food are based on knowledge of the following concepts:
1. Sensation attributes 2. Measurement of absolute sensitivity, or threshold 3. Scaling techniques 4. Psychophysical laws 5. Measures of time, such as reaction and time-intensity registers 6. Descriptive analysis
SENSATION ATTRIBUTES
A stimulus consists of an input of chemical or physical energy which is recognized by a receptor and causes a further response. Nerve impulses then travel from receptors through the nerves and towards the brain where different signals are processed, resulting in the corresponding sensations. All sensations exhibit a multiplicity of aspects, attributes, or dimensions, just as all stimuli are themselves multidimensional. An effective stimulus produces a sensation, the dimensions of which are quality, intensity, duration, and preference. Considering that most stimuli are multidimensional, abstraction is needed for the evaluation of the attributes of a stimulus. Attention must be focused on one aspect or attribute and many other aspects must be discarded. Therefore, what is to be measured must be defined precisely.
