Implicit versus explicit processing of visual, olfactory, and multimodal landmark information in human wayfinding

Abstract

Despite the predominant focus on visual perception in most studies, the role of humans’ sense of smell in navigation has often been neglected. Recent research, however, could show that humans are indeed able to use their sense of smell for orientation, particularly when processed implicitly. In this study, we investigate whether implicit perception of olfactory landmarks enhanced wayfinding performance compared to explicit perception. Fifty-two people completed a wayfinding and a recognition task in a virtual maze at two times of testing 1 month apart. Participants either received olfactory, visual, or both cues at the intersections. Wayfinding performance was better for olfactory landmarks, which were not correctly remembered in the recognition task. In contrast, wayfinding performance was better when visual landmarks were correctly remembered. In the multimodal condition, wayfinding performance was better with landmarks being remembered at t1 and remained the same at t2. Our results suggest distinct implicit processing mechanisms within the olfactory system and therefore hold important implications for the nature of spatial odor processing extending beyond explicit odor localization tasks. The study highlights the importance for future studies to develop and employ further experimental methods that capture implicit processing across all of our senses. This is crucial for a comprehensive understanding of consciousness, as olfaction strongly influences our behavior, but remains largely latent unless deliberately honed through practice.

The human sense of smell in spatial orientation: A state-of-the-art review.

“…Finally, numerous studies by us utilized similar methodological approaches and are therefore summarized here (see Arena & Hamburger, 2023; Hamburger & Knauff, 2019; Schwarz & Hamburger, 2024; Schwarz & Hamburger, 2023, for more details). Studies comprised a learning phase, a wayfinding phase, and/or a beaming phase (i.e., teleportation) and/or a recognition phase.…”

“…As mentioned above, Schwarz & Hamburger, 2024 revealed an advantage of olfactory landmarks compared to visual landmarks over time. Finally, Schwarz & Hamburger, 2023 compared implicit and explicit processing of visual, olfactory, and bimodal (Visual × Olfactory) landmarks and revealed better olfactory wayfinding performance when odors were processed implicitly (=not correctly identified as landmarks in the recognition phase) rather than explicitly. For the visual condition, the exact opposite result was observed.…”

“…The results demonstrate that humans possess the ability to navigate using their sense of smell. However, they only mark the beginning of further, future research, as many questions remain open, such as the multimodal utilization of landmarks (Schwarz & Hamburger, 2023), odor concentration effects, impact of odor composition on wayfinding (as reviewed by Young, 2020) or the use of the sense of smell in real-world navigation scenarios beyond experimental settings with odor plumes consisting of a mixture of odorants. These findings not only hold great potential for advancing our understanding of human orientation but also have implications across various domains beyond spatial cognition, given the unique characteristics of the sense of smell.…”

“…Results of recent studies point to the latter. They show, for example, that odors can only be localized when processed implicitly (Wudarczyk et al, 2016) or that olfactory landmarks lead to better wayfinding performance when not processed explicitly (Schwarz & Hamburger, 2023). These findings indicate that perceptual salience in odors does not necessarily have to occur on a conscious level of perception.…”