Averaged Evoked Responses to Light and Odorant Under Certain and Uncertain Conditions

Abstract

The Problem. To determine if the averaged evoked response to odorants was similar to the late positive component in the averaged evoked response to lights, both light and odorant were presented under two conditions to see if they would both occur under the same experimental condition and both be absent under the same condition. Procedure. A light and an odorant were presented to human subjects under two conditions, when the subject knew which of the two stimuli would be presented (certain condition) and when the subject did not know which of the two would be presented (uncertain condition). The averaged evoked responses to these two stimuli under the two conditions were compared. Findings. The late positive component in the response to light was significantly larger in the uncertain than certain condition as predicted. The response to odorants, however, was not found consistently or exclusively in the uncertain condition. Conclusions. The results are somewhat inconclusive as the response to odorant was not found consistently in at least one of the two conditions. However, the results do not support the hypothesis that the evoked response to odorant and the late positive component in the evoked response to light occur under the same conditions. Recommendations. A procedure under which the averaged evoked response to odorants can be reliably produced should be found before further attempts at determining its other properties are made. An exact replication of the study by Allison and Goff (1967) in which the evoked response to odorant was reported to be reliably produced is suggested.