Mood and personality interact to determine cognitive biases in pigs

Abstract

Cognitive bias has become a popular way to access non-human animal mood, though inconsistent results have been found. In humans, mood and personality interact to determine cognitive bias, but to date, this has not been investigated in non-human animals. Here, we demonstrate for the first time, to the best of our knowledge, in a non-human animal, the domestic pig (Sus scrofa domesticus), that mood and personality interact, impacting on judgement. Pigs with a more proactive personality were more likely to respond optimistically to unrewarded ambiguous probes (spatially positioned between locations that were previously rewarded and unrewarded) independent of their housing (or enrichment) conditions. However, optimism/pessimism of reactive pigs in this task was affected by their housing conditions, which are likely to have influenced their mood state. Reactive pigs in the less enriched environment were more pessimistic and those in the more enriched environment, more optimistic. These results suggest that judgement in non-human animals is similar to humans, incorporating aspects of stable personality traits and more transient mood states.

The relationship between personality and cognitionin the fowl, Gallus gallus

“…An association between personality and judgment has been observed in some species (e.g. Asher et al 2016;d'Ettorre et al 2016), but not in others (Lalot et al 2016), warranting further investigation of this possible association.…”

“…For example, proactive pigs interpreted ambiguous stimuli more optimistically than reactive pigs and were at the same time less plastic in their responses to ambiguous cues (Asher et al 2016). While reactive pigs showed an optimistic bias in an enriched environment that was reduced in a less enriched environment, proactive pigs where instead optimistic independent of environmental conditions (Asher et al 2016). In paper VI, I exposed individuals raised in the same environment to a judgment bias test.…”

“…The results so far suggest that personality can associate with judgment. For example, coping styles in pigs (Sus scrofa domesticus) and explorative behaviour in carpeter ants (Camponotus aethiops) were associated with variation in judgment bias (Asher et al 2016;d'Ettorre et al 2017). However, there are also studies that did not find an association between personality and judgment (Lalot et al 2016).…”

“…This has stimulated a handful of studies, exploring a link between personality and variation in judgment biases (e.g. Cussen & Mench 2014;Lalot et al 2016;Asher et al 2016;d'Ettorre et al 2017). The results so far suggest that personality can associate with judgment.…”

“…These results indicate that animal personality can affect cognition or at least biases in cognition. There are a handful of studies that have explored the relationship between personality and judgment biases in animals, none of which explored a causal relationship (Cussen & Mench 2014;Asher et al 2016;Lalot et al 2016;d'Ettorre et al 2017). For example, in parrots, attention bias was associated with personality (Cussen & Mench 2014).…”