Configural processing of odor mixture: does the learning of elements prevent the perception of configuration in the newborn rabbit?

Although elemental perception of odor mixtures allows us to perceive the component odor qualities, configural perception leads to the emergence of a new odor percept. The 6-odorant Red Cordial (RC) mixture is weak configurally perceived in newborn rabbits, meaning that pups respond to the odorants after conditioning to the mixture but cannot generalize to the mixture after conditioning to a single odorant. They need to know more than 50% of the elements to respond to the mixture. This suggests that their responsiveness to RC depends on the familiar vs. unfamiliar bits of information that they perceive in it. To go further, we tested the complementary hypothesis that after learning 4 or 5 odorants, the configural perception disappears, allowing pure elemental perception of the whole mixture. In Exp. 1, repeated conditionings to RC decreased the pups' responsiveness to the odorants, i.e., facilitated RC configural perception. In Exp. 2, pups were first conditioned to a sub-mixture of 4 or 5 RC elements and then repeatedly conditioned to RC to determine whether early elemental learning reduced the facilitation of RC configural perception. As pups weakly responded to the RC mixture components, the early conditioning did not prevent this facilitation. In Exp. 3, after daily conditioning to the sub-mixture and then to the whole mixture, the configural perception of RC remained unaffected. The present results confirm that rabbit pups respond to the configural RC mixture according to the perceived ratio of familiar/unfamiliar cues and highlight that the perception of the RC configuration resists the previous acquisition of elements that compose the mixture.