DIPLOMARBEIT Titel der Diplomarbeit „Rapid discrimination and categorisation of briefly flashed stimuli in the pigeon (Columba livia)“ angestrebter akademischer Grad Magistra der Naturwissenschaften (Mag. rer. nat.) Verfasserin: Katharina KRAMER Matrikel-Nummer: 9503431 Studienrichtung /Studienzweig (lt. Zoologie Studienblatt): Betreuer: Ao. Univ. Prof. Mag. Dr. Ludwig Huber Wien, im Februar 2010 Rapid discrimination and categorisation of briefly flashed stimuli in the pigeon 2010 CONTENTS SUMMARY ................................................................................................................................ - 1 - ZUSAMMENFASSUNG ...................................................................................................................................- 3 - 1. INTRODUCTION ...........................................................................................................................................- 5 - 1.1. Theories of stimulus classification ....................................................................... - 6 - 1.1.1. Visual discrimination ................................................................................................................... - 6 - 1.1.2. Visual categorisation ...................................................................................................................- 7 - The biological relevance of categorisation ................................................................ - 7 - Empirical evidence throughout the animal kingdom .................................................. - 8 - Empirical evidence in the pigeon ............................................................................... - 8 - 1.1.4. Rapid discrimination and categorisation ............................................................................ - 11 - “Reasons to be fast”................................................................................................. - 11 - Empirical evidence throughout the animal kingdom ................................................ - 11 - Empirical evidence in the pigeon ............................................................................. - 13 - 1.2. The visual capacities of pigeons .............................................................................. - 14 - 1.2.1. “The avian eye view” ................................................................................................................ - 14 - 1.2.2. Methods of rapid stimulus presentation ............................................................................. - 15 - 1.3. The aim of the study .................................................................................................. - 18 - 2. GENERAL METHODS.............................................................................................................................. - 19 - 2.1. Subjects ...................................................................................................................... - 19 - 2.2. Apparatus ................................................................................................................... - 20 - 2.3. Stimuli ......................................................................................................................... - 22 - 2.4. Procedure ................................................................................................................... - 23 - 2.5. Data Evaluation .......................................................................................................... - 27 - 3. THE EXPERIMENTS ................................................................................................................................. - 29 - 3.1. Pretraining .................................................................................................................. - 29 - 3.2. Experiment 1: Geometric Figures ............................................................................ - 30 - 3.2.1. Introduction ................................................................................................................................. - 30 - 3.2.2. Methods ....................................................................................................................................... - 32 - 3.2.2.1. Subjects and Apparatus .............................................................................. - 32 - 3.2.2.2. Stimuli ......................................................................................................... - 32 - 3.2.2.3. Procedure ................................................................................................... - 34 - Two-Components-Different training ......................................................................... - 34 - One-Component-Different training ........................................................................... - 35 - One-Presentation-Time test ..................................................................................... - 36 - Rapid discrimination and categorisation of briefly flashed stimuli in the pigeon 2010 Ultrarapid test ........................................................................................................... - 36 - 3.2.3. Results .......................................................................................................................................... - 37 - Two-Components-Different training ......................................................................... - 37 - One-Component-Different training ........................................................................... - 40 - One-Presentation-Time test ..................................................................................... - 46 - Ultrarapid test ........................................................................................................... - 48 - 3.2.4. Discussion ................................................................................................................................... - 50 - 3.3. Experiment 2: Natural stimuli ................................................................................................ - 57 - 3.3.1. Introduction .................................................................................................................................. - 57 - 3.3.2. Methods ........................................................................................................................................ - 59 - 3.3.2.1. Subjects and Apparatus .............................................................................. - 59 - 3.3.2.2. Stimuli ......................................................................................................... - 59 - 3.3.2.3. Procedure .................................................................................................... - 60 - One-Presentation-Time training ............................................................................... - 60 - Different-Presentation-Times training ...................................................................... - 61 - Generalisation test ................................................................................................... - 62 - 3.3.3. Results .......................................................................................................................................... - 62 - One-Presentation-Time training ............................................................................... - 62 - Different-Presentation-Times training ...................................................................... - 62 - Generalisation test ................................................................................................... - 64 - 3.3.4. Discussion ................................................................................................................................... - 66 - 4. GENERAL DISCUSSION ......................................................................................................................... - 74 - 5. REFERENCES ............................................................................................................................................. - 83 - ACKNOWLEDGEMENTS..................................................................................................................- 97 - DECLARATION...................................................................................................................................- 98 - CURRICULUM VITAE........................................................................................................................- 99 - Rapid discrimination and categorisation of briefly flashed stimuli in the pigeon 2010 SUMMARY Animals’ ability to analyse and categorise the visual environment as fast as possible is fundamental, as survival will often depend on the speed with which predators, food, or other relevant objects can be recognised. This study examines the conditions under which rapid visual processing occurs. The outstanding visual discrimination and categorisation abilities of pigeons (Columba livia) are well-documented in the literature. However, it is still unclear how quickly these birds may extract the pictorial information necessary to allow for correct classification. In the present study, the pigeons’ ability to solve a series of visual classification tasks with severe temporal restrictions was tested. With a modified go/no go- procedure, different types of images — simple geometrical stimuli (Experiment 1) and natural images that either showed