Differential learning and use of geometric angles by pigeons and humans

Abstract

The use of environmental geometry as a spatial cue is well established for a range of species. Previous research has focused largely on the use of global geometry (e.g., the shape of a room). Thus, comparatively less is known about how local geometry (e.g., corner angles within a room) is encoded. The purpose of the research presented in this thesis was to examine how angular information is encoded and to determine whether angle size influences encoding, using a discrimination task and a spatial array task. Chapter 2 presents a study during which pigeons were trained to discriminate between a small (60°) and large (120°) angle. Once the birds were accurately choosing the angle associated with reward, they were tested on their ability to discriminate between their training angle and one of a series of novel angles. The pigeons showed an absolute learning pattern for the small training angle, but not the large angle. The significance of this result is that the small angle may have been perceived as more distinctive compared to the large angle. Adopting a comparative approach, Chapter 3 presents a study during which adult humans were trained and tested using a similar paradigm but with different training angles (25°, 50° and 75°). The results of this study also support an absolute learning pattern for the small training angle but not the large. These results are significant in that they suggest that angle size may be an important local geometric cue that is encoded in a similar way by both pigeons and humans. To understand how angular information may be processed during a spatial task, Chapter 4 presents a study during which adult humans were trained and tested on their ability to use local angles (either 50° or 75°) to find a goal location within an object array. The results showed that the smaller angle was used more effectively as a spatial cue than the larger angle. Overall, these results are important as they suggest that small and large angles are encoded differently by pigeons and humans, with small angles perceived as more distinctive than large angles.