Effect of varying sucrose concentration on macrobehavioral aspects of licking in the rat

Rats (eight male, eight female) were trained to lick 32% and 4% sucrose solutions for three minutes per day on four consecutive days. Measures of the number of licks revealed robust positive and negative contrast effects. Analysis of the burst-pause pattern of licking revealed that the decrease in licking characteristic of the negative contrast effect resulted from a decrease in the number of bursts, while the increase in licking characteristic of the positive contrast effect was the result of a shortening of the interburst interval.