9 Springer-Verlag 1993 Discriminating parts from the whole: determinants of odor mixture perception in squirrel monkeys, Saimiri sciureus

Abstract. In a task designed to simulate olfactory-guided foraging, the ability of squirrel monkeys to discriminate an artificial 12-component odorant from 3-, 6-, 9- or l l-component submixtures was investigated. A combina-tion of factors was found to contribute to the animals' performance: 1. Discriminability generally decreased as the number of components in the submixture increased. 2. Submixtures did not contribute equally to mixture per-ception, and one component in particular (cineole) dis-proportionately influenced stimulus discriminability. 3. Interactive ffects between submixtures resulted in marked eviations from the general pattern of discrim-inability. 4. Changes in the relative concentration of submixtures could also influence discriminability. 5. Finally, individual differences in responsiveness to par-ticular stimuli were apparent. These findings demonstrate hat the interaction be-tween components in odor mixtures can be complex and that seemingly small changes in composition can strong-ly affect perception and thus potential signal function. It is therefore suggested that in future investigations of squirrel monkey semiochemistry, the method of system-atically varying submixtures may be particularly useful in defining the contribution of components o a signal