Pig your brain!
The study of animal behavior often reveals a world of intricate and strategic choices, challenging the long-held assumption that complex decision-making is a uniquely human trait. From the smallest insect to the largest mammal, every animal is constantly faced with a series of decisions that directly impact its survival and reproductive success. These choices, though often appearing instinctive or simple, are the result of a sophisticated interplay between an animal's genetics, its past experiences, and its immediate environment. Analyzing these behaviors allows us to better understand the evolutionary pressures that have shaped animal cognition and the diverse strategies they employ to thrive in a constantly changing world. The Animal Husbandry and Ethology Group (Lorenz Gygax) studied the effects of short-term emotion and long-term mood on Judgement Bias Tasks (JBT) in pigs. The pigs were trained to do a Go/No-go task under different circumstances. To affect the mood and emotion of some pigs, five minutes of positive interaction with a familiar human were used either during the 3 weeks of training (mood) or during the tests (emotion). Since results did not show significant differences between the groups and all pigs had developed a positive relationship with the experimenter over the course of the study, they concluded that another type of treatment would be better to study JBT when training requires regular contact with humans. If you want to know the details of the experiment, read the Applied Animal Behaviour Science Article.
Abstract
The Judgement Bias Task (JBT) is a promising proxy measure of animals’ affective states, a growing field in animal welfare science and beyond. However, it remains unclear if judgement biases are predominantly affected by long-term mood, short-term emotions or a combination of both. This study aimed to systematically disentangle the effect of mood- and emotion-inducing treatments on pigs’ decisions on a JBT using positive human-pig interactions as affect manipulation. Across three batches, thirty-six pigs were trained on a spatial Go/No-go task with active trial initiation. During the three weeks of training and during testing, 12 pigs were administered five minutes of positive interactions daily with a familiar human (MoodPlus), whereas the remaining 24 pigs did not receive such treatment (MoodMinus). When pigs were tested on the JBT, all 12 MoodPlus and 12 of the MoodMinus pigs received three test sessions that were preceded by five minutes of positive interactions (EmoPlus) and three test sessions without positive interaction before (EmoMinus). The remaining 12 MoodMinus pigs were allocated to a control group, which did not receive any specific positive interaction treatment. Thirty pigs (83 %) reached the learning criterion and were tested across six test sessions. Pigs from all treatment groups showed highly “optimistic” responses to all ambiguous cues, leading to a ceiling effect, which may have overshadowed potential treatment differences (all effects apart from cue type: X12 ≤ 1.75, p ≥ 0.19). Results from Human Approach and Avoidance Tests at the end of the study and the analysis of the behaviour of pigs during EmoPlus sessions indicated that all pigs, independent of treatment, had developed a positive relationship with the experimenter over the course of the study. These results suggest that positive human-animal interactions may not be an ideal treatment in the context of JBT when training requires regular contact with humans. MoodMinus pigs tended to respond more “optimistically” in EmoMinus sessions than Control pigs (X12= 3.58, p = 0.06), which may indicate a carry-over effect from EmoPlus to EmoMinus sessions. We call for future studies with a different treatment than human-animal interactions that implements both long- and short-term interventions in a systematic way to disentangle the effect of mood and/or emotion on judgement biases.