Variation in food-maximizing behaviour as a function of context, breed, and individual characteristics: A study of...

Food motivation is widely recognized as a fundamental factor shaping domestic dog behaviour. However, it remains unclear whether different behavioural experimental paradigms capture distinct motivational components, and whether factors known to shape dogs' food motivation differentially contribute to performance across these measures. We assessed Labrador Retrievers (n = 24) and German Shepherd Dogs (n = 24), breeds that are commonly characterized as highly food and toy responsive, respectively, across two food-maximizing behavioural paradigms: a progressive ratio (PR) task measuring effort expenditure and an uncertainty-based probabilistic choice task quantifying win-stay and lose-shift (WSLS) strategies. Using mixed-effects models, we found that Labradors reached significantly higher PR breakpoints than German Shepherd Dogs, with this difference persisting regardless of training level. Furthermore, age had a breed-dependent effect on PR performance, such that increasing age was associated with lower PR breakpoints particularly in Labradors. In the WSLS task, breed differences emerged only through interactions with questionnaire-based measures of food motivation: higher scores predicted increased win-stay and reduced lose-shift tendencies specifically in Labradors, consistent with sustained motivation to persist with a previously chosen option despite occasional nonreward. Behavioural characteristics also shaped outcome-dependent strategies, as higher owner-rated frustration was linked to increased switching tendency, particularly after rewarded trials. Together, these results demonstrate that different behavioural measures likely capture distinct dimensions of food motivation and predictors of food-maximizing behavioural tendencies are breed-dependent. A multi-measure approach is therefore essential for comprehensively evaluating how motivation translates into behaviour across diverse food-related contexts.