Exploring breed and individual variation in learning and behaviour of domestic dogs (Canis familiaris)

Centuries of selective breeding have produced domestic dog breeds with distinct physical and behavioural characteristics. However, in modern companion dogs, it remains unclear whether breed continues to represent a meaningful source of variation in learning and behaviour. The aim of my thesis was to examin behavioural variation across and within companion dog breeds, focusing on how breed-related differences interact with individual experience and context. Chapter 1 reviewed factors influencing behavioural development in domestic dogs and identified gaps in understanding the role of breed in modern dogs, where selection has increasingly shifted away from historical working functions. Chapter 2 addressed this gap by comparing core learning capacities, including discrimination learning, reversal learning, and resistance to extinction, along with emotionality among dogs from multiple breed clades. Breed clades differed in performance, but the direction and magnitude of differences depended on the specific component measured. Furthermore, predictors of within-breed variation differed among breed groups, suggesting that breed may influence how biological and environmental factors shape behaviour. Chapter 3 examined whether experience altered breed-related differences by reassessing the same dogs. Some learning components showed greater change than others, reducing the observed breed differences and suggesting that breed effects may be strongest during first task exposure. Chapter 4 investigated dogs that failed to meet performance criteria in the initial experiment and found systematic differences in age, reward responsiveness, and training experience compared with successful dogs, highlighting the importance of considering variation beyond high-performing individuals. Chapter 5 examined reward motivation as a source of individual variation using Labrador Retrievers and German Shepherd Dogs in tasks assessing food-motivated behaviour under different contexts. Results showed that breed directly influenced effort expenditure, whereas outcome-based decision-making was shaped by interactions between breed and measures of individual food motivation. Overall, my thesis findings demonstrate that breed remains a meaningful source of behavioural variation in modern companion dogs, but breed effects are context-dependent and influenced by prior experience and individual characteristics. These findings support a multilevel perspective in which behavioural differences among breeds emerge through interactions between biological predispositions and environmental influences rather than differences in cognitive ability alone.