The Human Sense of Smell in Spatial Orientation: A State-of-the-Art Review

An old misconception led to the belief that humans have a poor sense of smell. The sense of smell is a rather primitive but important sense that our ancestors used for hunting, mating, and survival. Throughout the past decades and even centuries, the importance of this sense for our daily lives has been lost under the assumption that "humans have a bad sense of smell." Especially in combination with spatial orientation and navigation, the sense of smell is of particular importance in a lot of our close relatives in the animal kingdom. Research on humans reveals an immense gap here compared to research on nonhuman animals. However, there are some findings that suggest that olfaction is also important in human navigation: Olfactory cues are more emotional-laden and memorable than visual cues and it is evolutionary only logical that humans, similar to their close relatives from the animal kingdom, use their sense of smell for orientation as well. Therefore, it is very likely that humans, similar to other animals, use their olfactory system for navigation. The main difference is that humans are not consciously aware of it. As we outline in this review, several findings may explain why olfactory navigation in humans is primarily an implicit process and why it has mainly been neglected in the past. We further give suggestions for future research and how findings in olfactory human navigation can be used for other field outside wayfinding, such as aromatherapy or Alzheimer's diagnosis.