Sylvie cannot wait to get home from school to play with the puppy she was given for her birthday. The moment she opens the door it will come rushing down the hall and jump up at her. Then it will run around and around in circles, hoping to be taken out and have a ball thrown for it. What a happy animal!

Or is it? After all, it could be that the puppy is wild with frustration after being kept indoors for too long. Sylvie might simply be anthropomorphising: that is, looking at an animal as if it is a human being.

This was the kind of problem raised at the Animal Welfare Assessment Contest held at Wisconsin University last November. Veterinary students came from all across the US and Canada to take part.

The students were divided into teams and asked to think about three different animals: bisonA wild ox, with a humpback and shaggy hair, native to North America and Europe. , hens and tortoises. They had to decide whether these were better off being kept in a restricted environment controlled by humans or left to range comparatively freely.

In the case of the tortoises, one group were kept in a suburban zoo and given toys to play with. Another group were kept in a large enclosure in the desert where they naturally live.

One team argued that bison were better off being allowed to roam freely, so that they could behave as herds normally due. The tortoises, on the other hand, were better off in the zoo, where they were protected from the dangers of desert life and enjoyed the stimulation of toys and human contact.

The judges, though, disagreed. They argued that wild animals can only thrive if they have as little contact with humans as possible.

But whether thriving and being happy are the same thing is another question. In his essay What Is It Like To Be A Bat? the philosopher Thomas Nagel argues that we cannot say:

"It will not help to try to imagine that one has webbing on one's arms, which enables one to fly around at dusk and dawn catching insects in one's mouth... it tells me only what it would be like for me to behave as a bat behaves."¹

Others, though, argue that we can tell how animals feel by observing them: for example, what they choose to do and how they react in different situations. It is easy to see when an animal is frightened, since it will freeze, run or shy away from danger.

A group of scientists recently used AIA computer programme that has been designed to think.  to try to interpret the grunts of pigs, using 7,000 recordings. They claimed that they could accurately tell what the animals were feeling 92% of the time.²

Other researchers have worked on animals' facial expressions. They say that you can measure fear or pain in them by signs such as changes in ear positions or how much they show the whites of their eyes. Some animals, though, tend not to show such emotions in case it encourages predatorsAnimals that prey on and eat other animals. to attack them.

Measuring an animal's heartbeat is another method. As with humans, an increased heart rate is an indication of fear or stress. Levels of hormonesChemicals created inside living creatures. They are used to send messages from one part of the body to another. such as adrenalineA hormone made by the body in response to a stressful or threatening situation. can be used to measure stress.

Can we know what animals are feeling?

Yes: It is easy to see when they are scared or angry or depressed. What we can observe for ourselves is now being backed up by biological measurements and analysis aided by AI.

No: We are always tempted to anthropomorphise, but we know very little about how animals' minds work. As Thomas Nagel says, they are so different that comparing their experience to ours makes no sense.

Or... We can tell when they are frightened or stressed, because that is directly reflected in their behaviour. It is much harder to tell if they are happy, or even if they know what happiness is.

Bison - A wild ox, with a humpback and shaggy hair, native to North America and Europe.

AI - A computer programme that has been designed to think. 

Predators - Animals that prey on and eat other animals.

Hormones - Chemicals created inside living creatures. They are used to send messages from one part of the body to another.

Adrenaline - A hormone made by the body in response to a stressful or threatening situation.