Optimism, pessimism and personality in dogs

Scientific studies carried out in human psychology have reported that the valence of an individual’s emotional state may influence a number of cognitive functions including attention, memory and judgement. That is, for example, if a person is in a negative mood or affective state (e.g. state of anxiety), he/she will me more likely to retrieve negative memories or to make negative judgments about future events or ambiguous stimuli. It’s basically the concept of the glass: if we are in a good, positive mood we see the glass half full (optimistic bias), if we are anxious or in a negative state we tend to see the glass half empty, thus making a pessimistic judgement.

There is growing evidence that emotions can influence cognitive functions by biasing environment perception in non-human animals too. However, unfortunately for us, we are not able to just ask animals how they are feeling so we need to find different strategies and proxy measures to assess their affective state.

A very popular tool used for this purpose is the Judgement Bias Test (JBT). The JBT is based on the idea that a subject will show a behaviour indicating anticipation of either relatively positive or relatively negative outcomes in response to affectively ambiguous stimuli.

So how it works is that an animal will learn to associate a positive cue (P) with a positive outcome (e.g. treat) and a negative cue (N) with a negative or neutral outcome (e.g. no treat). After a few trials, the animal will anticipate a treat and run faster to the P cue or anticipate no treat and go slower or not at all to the N cue. At this point, the subject will be presented with a middle, ambiguous cue (NP, M or NN in the picture). According to the half full/half empty glass concept, we would expect an animal in a positive affective state to expect a positive outcome from the ambiguous cue, thus run faster to it (optimist) or on the contrary we expect an animal in a negative affective state to expect a negative outcome, thus take more time to reach the ambiguous cue (pessimist).

Image from Barnard et al. (2018) Scientific Reports 8:6660

..but how is this all linked to personality?

Again studies in humans showed how personality traits, and not only mood, may also affect the cognitive processes mentioned above. So, for example, neuroticism is found to be predictive of negative judgement and extraversion of more positive ones. Hence, personality likely to be a key element in the decision making process also of non-human animals. In the past decade, the scientific community has shown a lot of attention to measuring emotional processing in non-human animals using cognitive approaches. However, so far, the influence that personality may have on cognitive bias tasks has been largely overlooked.

And this is exactly what I tried to do in one of my recent studies. I investigated the influence of personality traits on the decision-making process of the domestic dogs during a judgement bias test.

My results showed that dogs scoring higher on sociability, excitability and non-social-fear had shorter response latencies to cues in an ambiguous location, indicating a more ‘optimistic’ bias. In contrast, dogs scoring higher on separation-related behaviour and dog-directed-fear/aggression traits were more likely to judge an ambiguous stimulus as leading to a negative outcome, indicating a more ‘pessimistic’ bias.

Results, partially consistent with previous findings in humans, indicate that personality may plays a role in the cognitive processing of environmental stimuli in the domestic dog.