Odour-Evoked Memory in Dogs: Do Odours Help to Retrieve Memories of Food Location?

SIMPLE SUMMARY: The ability of odors to evoke past memories has been widely reported in humans. Although olfaction is generally considered as the most important sense in dogs, little is known about its relationship with memory in this species. To investigate this issue, we trained dogs to memorize the location of five rewards while a specific odor (i.e., vanilla) was dispersed in the environment. After 24 h delay, dogs were divided in three groups, which performed two trials of the same spatial task in different conditions. The first group received a control odor (i.e., apple) in the first trial and the vanilla odor in the second trial; vice versa, the second group was exposed to the vanilla odor in the first test and to the apple odor in the second one. The third group, instead, performed the tests with no odors. We found that the exposure to vanilla odor significantly improved dogs’ performance in the spatial task, suggesting that the odor aided dogs to recall specific and detailed memories originally formed in its presence. ABSTRACT: The ability of odors to spontaneously trigger specific memories has been widely demonstrated in humans. Although increasing evidence support the role of olfaction on dogs’ emotions and cognitive processes, very little research has been conducted on its relationship with memory in this species. The present study aimed at investigating the role of olfaction in the recall of detailed memories originally formed in the presence of a specific odor (i.e., vanilla). To test this, three groups of participants were trained with the same spatial learning task while a specific odor (i.e., vanilla) was dispersed in the testing room. Subjects were then divided in three experimental groups and after 24 h delay, they were presented with the same spatial task. The first group (Group 1) performed the task in the presence of a novel odor (i.e., control), whereas the second (Group 2) and the third group (Group 3) carried out the test in the presence of the vanilla odor and no odor (Group 3), respectively. After a brief delay, the test was presented again to the three groups of dogs: subjects of Group 1 were now tested in the presence of the vanilla odor, whereas the Group 2 was tested with the control odor. The Group 3 received no odor in both tests. A significant improvement of dogs’ performance was registered in the control-vanilla odors condition (Group 1), suggesting that the exposure to the odor presented at the encoding time would prompt the recall of spatial memories in dogs.