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'Optimism' in Animals

'Optimism' when talking about animals is a kind of shorthand for 'a judgement or expectation bias towards positive outcomes', and 'pessimism' means 'a judgement or expectation bias towards negative outcomes'. Judgement bias is a type of cognitive bias.

Cognitive Bias

A cognitive bias is where an individual tends to perceive events in a biased way. There are many kinds of cognitive bias in humans. Check out the Wikipedia list of cognitive biases for the full smorgasbord. Some cognitive biases are influenced by an individual's emotional state. For example, if life has been giving you nothing but lemons lately, you are likely to see the glass as half empty. You will tend to expect more lemons. But if life has been coming up roses lately, you are likely to see the glass as half full and expect more roses.


Cognitive Bias in Animals

Animals show this cognitive bias as well. Studies on rats, starlings, sheep and bees have shown that animals experiencing a positive emotional state show a positive judgment or execptation bias. They judge ambiguous signals as indicators of positive outcomes. Animals experiencing a negative emotional state judge ambiguous signals as indicators of negative outcomes and expect negative thing to happen to them. This is exciting because it gives us a window into how an animal is feeling that does not depend on subjective interpretations of their behaviour or invasive measures of their physiology. Instead, we need only 'ask'.

The way to test an animal's cognitive bias is to train them to tell the difference between a positive signal and a negative signal. Generally, the positive signal is paired with a reward and the negative signal with an aversive experience or a disappointment. The animals show us they can tell the difference when they are quick to respond to positive signals and avoid responding to negative signals. Then we give them new, probe signals that are neither positive nor negative, but somewhere in between. How quickly they respond to those probe signals may be an indication of whether they interpreted a probe signal as positive (optimistic) or negative (pessimistic).

In this diagram, the black note and white note represent known signals (positive and negative). The grey notes in between represent ambiguous signals. How the animal reacts to grey notes tells us whether they took it to be a positive signal or a negative signal.

As an example, if white is our negative signal and an animal responds to the two light grey notes before the white one quickly, we would assume the animal interpreted those two notes as positive. Because those two notes are closer to the negative signal than the positive signal, we would assume it is an optimistic animal. If an animal abstains from responding to notes closer to the black note than the white, we would assume the animal had interpreted those signals as negative even though they were more like the positive signal and therefore they would be pessimistic. Seeing as judgement bias is influenced by emotion, we can then say the pessimistic animal may be in a negative emotional state and the optimistic animal may be in a positive emotional state.

It is uncertain how sensitive this method is at picking up changes in emotional states. It may depend on the animal or how strong the contrast between positive experiences and negative experiences. Animals tend to show a strong judgement bias when their housing is changed, but the effect fades over time as the animals get used to their new surroundings.

What About Personality?

There are also some studies that suggest personality may have a strong effect on cognitive bias in animals. Pessimism has been linked with stereotypies in capuchin monkeys and starlings. Stereotypies are repetitive behaviours that serve no real purpose, and are often an indicator of distress. Furthermore, dogs that display behaviours associated with separation-related distress also test more pessimistic than dogs that do not display those behaviours. Humans can be optimistic or pessimistic by nature, so perhaps animals can be as well. Indeed, a very recent study on rats shows that individuals that test more pessimistic in normal conditions are more vulnerable to stress-induced anhedonia, which is basically stress-induced depression. What this means for dog owners and trainers is that we may be able to use cognitive bias as an indicator of personality as well as emotional states. And that may help us decide how best to approach training and management to play to our dog's personal strengths.

If you would like to know more, you are welcome to contact me or look at the Further Reading section of this website.


Last updated: October 2013