On The Measurement and Modification of the Olfactory Responses of Blowflies

Abstract

The accuracy of the control of the olfactory stimulus was tested by balancing olfactory and visual stimuli of different intensity. This demonstrated that a reasonably accurate control of the intensity of the olfactory stimulus was achieved, and also disclosed some facts about the quantitative relationship of stimulus to response. These flies are normally repelled by menthol but their response to the odour of this substance was modified when they first experienced it in the larval stage or immediately upon emergence. The menthol of an experience in the larval stage thus survives metamorphosis and affects adult behaviour. Most of the flies then became ‘habituated’ to the odour, but in one case they appear to have become ‘conditioned’. The latter may be a case of ‘latent learning’. There was no modification of the response of adults which first experienced the odour when they were several days old. The populations of habituated or conditioned flies were not homogeneous. Different samples of populations which seemed at first to be indifferent to the odour of menthol often proved to respond differently, some being repelled by it, others indifferent or even attracted to this odour.