Flavor preferences conditioned with starch in rats

Abstract

Rats were trained to associate artificial cherry or grape flavors with 1% starch suspensions. Conditioning was assessed by offering the rats a choice of the cherry versus grape flavors without starch. Conditioned preferences were moderately strong and persistent; 3 days of conditioning produced a preference that did not fully extinguish within 18 days. Food deprivation substantially increased intake of 1% starch suspension. However, the degree of preference conditioned was not influenced by the availability of food during the conditioning period; the rats that had been food deprived during training acquired as strong a preference as did those fed freely during training. The degree of preference obtained was similar in the rats given reinforcing and nonreinforcing fluids simultaneously or sequentially. Starch conditioned a slightly stronger preference than did the same concentration of glucose, even though these substances contain the same amount of calories. A statistically significant, but weak, preference was conditioned by 0.5%, but not by 0.25%, starch. It is proposed that the flavor of starch, independent of its calories, is reinforcing to rats. 181Pairing a flavor with a nutrient increases subsequent preference for the flavor

Acquisition and extinction of flavour preferences conditioned by caffeine in humans

“…Other researchers have produced similar findings using different flavoured nutritive and non-nutritive solutions (e.g. Fedorchak & Bolles, 1987;Ramirez, 1994;Tordoff et al, 1990).…”

Persistence of conditioned flavor preferences is not due to inadvertent food reinforcement.

“…High resistance to extinction has also been reported previously for flavor preferences produced by various differential conditioning procedures intended to favor either flavor-calorie or flavorflavor learning (Capaldi et al, 1983;Fedorchak, 1997;Ramirez, 1994). In these studies, conditioned preferences have been measured in two-bottle tests by comparing intakes of CSϩ flavor with intakes of CSϪ flavor.…”

The nature and strength of caloric conditioning.

“…The basic preference was still there, but now it was one that remained stable in the face of changing hunger levels. It is interesting that Ramirez (1994) found, after 4 days of extinction, that a still reliable dextrose-reinforced flavor preference was also unaffected by increases in hunger level. He did not evaluate the effect of hunger prior to extinction, so it is not clear whether his data show a loss of the effect or the hunger effect was not there to begin with.…”