A quantitative comparison of taste reactivity behaviors to sucrose before and after lithium chloride pairings: a unidimensional account of palatability.

Alterations in the motivation to ingest sucrose can be quantified by measuring the number and type of oral motor and somatic responses (i.e., taste reactivity [TR]) that are elicited by sucrose. In 2 experiments, rats had intraorally infused sucrose paired with LiCl injections for several trials, or they were injected with LiCl and had sucrose infused every 5 min during the 30-min postinjection period (data from Spector, Breslin, & Grill, 1988). In both experiments, ingestive TR responses decreased, whereas aversive TR responses increased over trials. Individual response components that comprise the ingestive and aversive categories followed the same trends of increase or decrease but changed at different rates as a function of number of trials or exposures. Overall, the array of response components could be projected onto a single unidimensional scale of palatability to capture the motivational states that ranged from acceptance to rejection.