Processing and Integration of Sensory Information in Spatial Navigation

As nomads, humanity constantly moved and relocated for hundred thousands of years. Thereby, individuals or small groups of people had to navigate over very long distances in order to survive. As a result, successful spatial navigation was one of the key cognitive abilities, which ensured our survival. Although navigation has nowadays become less life-threatening, exploring our environment and efficiently navigating between places are still very important aspects in our everyday life. However, in order to be able to navigate efficiently, our brain has to perform a series of spatial cognitive operations. This dissertation is structured into three sections, which explore these cognitive operations from three different perspectives. In the first section I will elaborate about the role of reference frames in human spatial navigation. Specifically, in an online navigation study (study one) I will show that humans have distinct but stable reference frame proclivities. Furthermore, this study demonstrates the existence of a spatial strategy, in which the preference to use a particular reference frame is dependent on the axis of rotation (horizontal vs. vertical). In a follow-up study (study two) I will then analyze the factors underlying performance differences in navigation, as well as individual preferences using one or another spatial strategy. Interestingly, the results suggest that performance measures (reaction time and error rate) are influenced mostly by the factors gender and age. However, even more importantly, I will show that the prevalent factor, which influences the choice for an individual navigation strategy, is the cultural background of the participant. This underlines the importance of socio-economic aspects in human spatial navigation. In the second part of this thesis I will then discuss aspects of learning and memorizing spatial information. In this respect, the alignment study (study three) will show that humans are able to recall object-to-object relations (e.g. how to get from A to B) in a very brief time, indicating that such information is directly stored in memory. This supports an embodied (action-oriented) perspective of human spatial cognition. Following this approach, in the feelSpace study (study four) I will then investigate the long-term training effects with a sensory augmentation device. Most importantly, the respective results will demonstrate substantial changes in the subjective perception of space, in sleep stage architecture, and in neural oscillations during sleep. In the third and last section I will describe the importance of multimodal processes in spatial cognitive operations. Most importantly, in the platform study (study five) I will combine the topics of sensory augmentation and Bayesian cue combination. The results of this study show that untrained adult participants alternate rather than integrate between augmented and native sensory information. Interestingly, this alternation is based on a subjective evaluation of cue reliability. In summary, this thesis will present relevant and new findings for better understanding spatial strategy formation, learning and representing spatial relations in memory, and multimodal cue combination. An important and overarching aspect of this thesis is the characterization of individual differences in the context of human spatial navigation. Specifically, my research revealed individual differences in three areas: First, in utilizing egocentric or allocentric reference frames for spatial updating, second in individualized qualitative changes of space perception during long-term sensory augmentation, and third, in preferences to use native or augmented information in a cue combination task. Most importantly, I will provide a better definition and understanding of these individual differences, by combining qualitative and quantitative measures and using latest technologies such as online data recordings and interactive experimental setups. In fact, in the real world, humans are very active beings who follow individualized spatial cognitive strategies. Studying such interactive and individualized behavior will ultimately lead to more coherent and meaningful insights within the human sciences.