Reinforcement and Inhibition of Eyelid Reflexes

Taste preferences, as measured in 48-hour, Richter-type drinking tests (test solution opposite distilled water), were determined for northern grasshopper mice (Onychomys leucogaster, ssp. breviauritus). The Ss were nine males and nine females which were individually housed within an environmental chamber. The test solutions were prepared from five sugars (fructose, glucose, lactose, maltose, sucrose), three salts (magnesium sulfate, potassium chloride, sodium chloride), and two acids (citric acid and hydrochloric acid). In randomly assigned order, each sugar and each salt solution was presented at five molar concentrations, and each acid was paired with distilled water at six levels of pH. Strong drinking preferences were shown for all concentrations of the sugars above .05?.10 M, and sugars ranked in order of preference as follows: Maltose = sucrose > glucose = fructose > lactose. Preferences were also shown for hypotonic concentrations of NaCl. The other salts and both acids, however, were indifferently preferred at low concentrations and were rejected at the higher concentrations. Taste preferences by grasshopper mice for these chemicals were similar to those exhibited by Mongolian gerbils tested with the same items. The similar patterns of preference shown by New World cricetid rodents (grasshopper mice) and Old World cricetid rodents (gerbils) suggest that conclusions concerning disparity in taste sensibilities among animal forms may be premature.