Abstract:
Navigating in an environment and interacting with other people is an everyday behavior. In humans, these actions have underlying representations both of the environment and of the persons’ identities one meets. While there was already substantial research in these fields, many results are still inconclusive. Especially the actor oneself was often neglected. Hence this doctoral thesis is focused on the role of the actor in both face recognition and place recognition.
Face recognition and representation was investigated in the first three experiments. In experiment 1, classic discrimination and categorization tasks were conducted and extended with own faces of the participants themselves. An increase of discrimination performance at the category boundary was expected. In experiment 2, the face-space and natural occurring shifts within were investigated. Two factors (similarity between faces and distinctiveness of a face) were hypothesized to play a role in this shifting. In experiment 3, identity priming was tested with faces of the participants themselves and other faces as well as the influence of names.
Results showed that in experiment 1 there was no increased discrimination performance at the category boundary, which could be explained by the level of familiarity with the faces. However, an increased performance could be found for faces containing oneself. In experiment 2, natural shifts within the face-space consisting of the presented faces were described. A correlation between similarity ratings and shifts was present for female faces. Results of experiment 3 showed an artificially induced shift congruent with the priming stimuli. Names can also cause priming effects; however, these effects are different when names are used as instruction. A priming model was designed that considers the results of the aforementioned experiments and that can explain the response time curves, indicating an influence of the task instructions. The results fit to the IAC-model of face recognition and are discussed along with brain regions involved in face recognition.
In the second part of this thesis, two experiments were carried out to investigate spatial navigation. In experiment 4, passers-by were asked at different locations around town to sketch one of two well-known city squares. Therefore, they had to recall the squares’ layouts from long-term memory. In experiment 5, passers-by around town were presented with views (photographs) of different city squares and they should judge if it was a certain one (market place).
Results showed that the sketches of experiment 4 had a general orientation bias - caused by the city layout - and were also oriented in relation to the participants’ location towards the square. Results indicated a regionalization both by distance and the city layout. Participants’ spatial representations at distant locations were different from those nearby the square. Experiment 5 showed that participants’ response times differed in dependence on their distance from the square, revealing a negative correlation with distance. Furthermore, it was indicated that views that one would see upon approaching the square from the respective interview location were identified faster. The results of both experiments are supported by and discussed along with a viewgraph model. In this model the views of different places are stored and connected by instructions how to get from one view to another.
In addition, differences and commonalities between face and place representation are discussed along with the involved brain regions. While mostly separate, there are also structures that are recruited in both cases. In turn, there are separate areas in the brain that fulfill comparable roles in these tasks. Finally, in both representations the “self” plays an important role. It is treated separately both functionally and anatomically and influences other representations.
representation