Perceptual scientists often study sensory responses at two levels: responses to weak and to strong stimuli. The simplest form of weak stimulus study is the measurement of absolute detection threshold. In taste research, this is the lowest level of a sapid chemical that can be distinguished from pure water. Threshold concentrations for taste stimuli range from micromolar (μmol) levels for [Page 982]many toxic compounds, such as quinine (a commonly experienced bitter drug and beverage fla-vorant) to low millimolar (mmol) ranges for NaCl (a salty stimulus), citric acid (a sour stimulus), and glutamate (a savory stimulus), and even to higher millimolar range for some sugars (sweet stimuli). The simplest form of a strong stimulus study is the measurement of sensation magnitude with questions like, “How strong ...