Odor effects in latent extinction

Abstract

Two experiments were presented, both of which investigated the role of odors of "frustration" or "stress" in the latent extinction situation. Experiment I involved two groups of rats, one entering the alley only when a stringent odor control procedure was in effect (Group NO), and one encountering no odor control procedure at all. During acquisition, Group NO ran faster on the first than on the second trial of each day, in contrast to the usual "warm up" effect. No differences between the groups was observed in extinction, apparently because the odor control procedure was ineffective in removing odors accumulated during nonrewarded goalbox placements and extinction trials. Experiment II involved three separate comparisons or designs each of which investigated a different question. The first comparison investigated the effect of the source of the odor emissions (i.e., from the same or another S) during extinction. The source of the odor apparently had little effect. The second comparison investigated the effect of site-of-placement (goalbox or neutral box), and the effect of the presence (or absence) of odor emitted during placements in the goalbox during extinction. The goalbox placement groups entered the goalbox more slowly than the neutral placement group early in extinction but more rapidly by the last extinction trial. The groups encountering odor in the goalbox ran more slowly on early extinction trials than the no-odor Ss. but the difference disappeared later in extinction. The third comparison involved the presence or absence of odor in the goalbox during placements as two levels of one factor and the presence of odor during extinction as the two levels of a second factor. The presence of odor during placements only affected speeds on subsequent trials if odor was also present on those trials, while odors in the goalbox during extinction lowered speeds regardless of the odor conditions during placement. The expectancy (Seward & Levy, 1949) or the r_g extinction interpretations of latent extinction apparently cannot account for the data. A frustration interpretation can explain the results of Comparisons 2 and 3 only if the assumption is made that odors become salient cues to which the primary frustration response is attached during the placement period. An interpretation of latent extinction based on the existence of a hierarchy of stimulus dimensions was proposed to account for the results. The basic assumptions of the interpretation are (1) odors act as conditioned aversive stimuli as well as unconditioned aversive stimuli; (2) if odors are present during a "frustrating" situation such as nonrewarded placements, these odors become the most salient cues in the situation; and (3) if no odors are present, other stimuli become salient cues.