Experimentalpsychologische Untersuchungen zu Navigationsstrategien unter Berücksichtigung endokrinologischer und physiologischer Variablen

Abstract

Sex differences in spatial navigation tasks are often reported. The use of different strategies is being discussed as the main cause of these differences. Among evolutionary and psychosocial factors there are also biological factors such as sex hormones being considered as potentially exerting an influence either on performance or on strategy use. A problematic aspect in most of the previous studies is the variation of given descriptions and conceptualizations of these strategies. Navigation strategies are rarely deduced explicitly from theory or are not empirically established. Commonly, they are investigated via self-ratings or subjective descriptions. To explore sex differences and the influence of sex hormones on strategy preferences it was therefore necessary to analyze and evaluate previous concepts of navigation strategies. An operationalization of the strategies via questionnaires appeared to be insufficient; instead an experimental approach was preferred. In addition, the mapping of neuronal activation patterns during the course of navigation tasks and in relation to the navigation strategy used, was meant to provide further information about underlying cognitive processes. Therefore, the aim of this study was a differentiation of navigation strategies via behavioral, fMRI and questionnaire data. The reported work can thus be seen as a precondition for a more in-depth examination of sex differences in strategy use and further influencing factors like sex hormones. For this purpose two navigation strategies were differentiated in a virtual maze. These two strategies were dubbed internal and external strategy and are normally described as egocentric and allocentric or spatial and non-spatial strategy. Commonly they are called place or response strategy. In contrast to previous findings, in the present studies I found that the so called egocentric, and non-spatial, internal or response strategy fulfills the criterion of an allocentric, and spatial strategy and the so called allocentric, and spatial, external or place strategy fulfills the criterion of an allocentric, and spatial strategy. An accurate assessment of these findings shows that both strategies (internal vs. external) have no correlation with an underlying spatial reference frame like the egocentric and allocentric, apparently contradicting former studies. Furthermore, the convention to regard the external strategy as a spatial strategy and the internal strategy as a non-spatial strategy has to be reconsidered. The results point towards the contrary: the external strategy seems to be of a rather non-spatial nature and vice versa. In the light of these compelling results, former attempts at strategy classification have to be reassessed and appear to be insufficient, oversimplifying, and even partly incorrect. A satisfying interpretation of sex differences in strategy use is therefore difficult to achieve, especially as no noticeable sex differences could be discovered in the behavioral data set. Sex differences could however be found in the neuronal activation patterns, which indicates sex differences in the cognitive processing during navigation. Additionally, the use of an external strategy was positively correlated with the progesterone level in spontaneously cycling women. Also, sex hormones were found to be modulating neuronal activation in brain areas which are important for navigation. Altogether, on the basis of the empirical data obtained in our studies, it can be reasoned that sex differences in strategy choice had formerly been described using insufficient concepts. The two strategies of the present studies appear to be valid concepts which show different neuronal activation patterns and evoke different answers in strategy questionnaires. Yet, they do not represent the whole complexity of navigation strategies. Specifically, they do not suffice to satisfactorily explain sex differences. Future investigations should therefore expatiate on navigation strategies and should refrain from simply importing prior concepts.