Preference differences for sucrose solutions in young and aged squirrel monkeys.

Licking patterns and molarity preferences, elicited by two sets of sucrose solutions (0.0 to 1.75 M and 1.0 to 3.0 M), were measured in six young and six aged squirrel monkeys. Sucrose preference thresholds were determined for each age group using sucrose concentrations from 0.025 to 0.1 M. Age was unrelated to sucrose preference thresholds. Consummatory activity of all monkeys increased monotonically as sucrose concentrations increased from 0.0 to 1.0 M. Aged, but not young, monkeys continued to increase consumption until sucrose concentrations exceeded 1.5 M. All monkeys increased consumption by increasing number of licks, number of licking bursts and total time spent licking. Unlike young monkeys, aged monkeys displayed high within animal variability of tongue contact times, exponentially decreasing rates of licking at high molarities, constant consumption efficiency decrements, and consistent negative correlations between tongue contact and following tongue off times.