Pigs learn to understand mirrors

Oct 09, 2009 by Lin Edwards weblog
A domestic pig on an organic farm in Solothurn, Switzerland. Image: Wikimedia Commons

(PhysOrg.com) -- A study of domesticated pigs has found that with just a little experimentation they can find food based only on a reflection in a mirror.

The study, carried out by Donald M. Broom, Professor of Animal Welfare at Cambridge University in the U.K., found that given a chance to familiarize themselves with a mirror first, most can find food based only on its reflection. Pigs that are not familiar with mirrors look behind them for the food.

In the study, soon to be published in the journal , four pairs of domesticated pigs were allowed to familiarize themselves with a mirror for five hours. They generally approached it cautiously at first, ending with their noses pressed against the mirror, but one pig charged at its reflection and broke the mirror. They looked behind the mirror, and watched their own reflections moving in front of it.

After familiarization, each pig was placed in a pen with an angled mirror and a partition, behind which were treats such as apple slices or M&Ms. Seven of the eight pigs immediately looked behind the partition and found the food. A control group of pigs that had never seen a mirror before searched behind it for the food.

Professor Broom said the study shows pigs have a high degree of what he terms assessment awareness, or the ability to use memories and observations to quickly learn to assess a situation and act on it.

According to Marc Hauser of Harvard's Cognitive Evolution laboratory, an understanding of reflections in mirrors has been demonstrated in other nonhuman before, but it is paradoxical that many don't seem to recognize their own reflections.

Researchers have confirmed this by marking a spot on the animal with dye and seeing if they try to remove the spot when they see it reflected in a . Only a few, such as bottlenose dolphins, apes, elephants, and magpies, recognize the mark as being on their own bodies. Professor Broom said he had tried marking the pigs, but they took no notice. He said this is hardly surprising because pigs often get marks on their bodies.

The study proves pigs have awareness, and Broom said that if an animal is known to be clever it is less likely to be treated as a food-producing machine and more like a sentient being. Perhaps the conditions in which pigs are raised, including overcrowding, which do not meet the needs of the animal, may be improved as a result of the study.

via Sciencenews.org
© 2009 PhysOrg.com

Explore further: Scientists discover new 'transformer frog' in Ecuador

Related Stories

Pigs prefer 3 square meals a day

Jun 24, 2008

Pigs raised in conventional indoor pens have different feeding patterns from those raised under more natural conditions. Research published today in BioMed Central's open access journal Acta Veterinaria Scandinavica shows ...

Michigan wants hunters to shoot feral pigs

Jan 30, 2008

Feral pigs have become such a problem in Michigan that the state Department of Natural Resources has asked deer hunters in 51 counties to shoot any they see.

Ecstasy causes depression in pigs

Mar 10, 2006

Danish scientific experiments where Ecstasy was adminstered to pigs may help to explain depression in humans abusing the drug.

Recommended for you

Scientists discover new 'transformer frog' in Ecuador

8 hours ago

It doesn't turn into Prince Charming, but a new species of frog discovered in Ecuador has earned the nickname "transformer frog" for its ability to change its skin from spiny to smooth in five minutes.

US gives threatened status to northern long-eared bat

11 hours ago

The federal government said Wednesday that it is listing the northern long-eared bat as threatened, giving new protections to a species that has been nearly wiped out in some areas by the spread of a fungal ...

Mice sing like songbirds to woo mates

11 hours ago

Male mice sing surprisingly complex songs to seduce females, sort of like songbirds, according to a new Duke study appearing April 1 in the Frontiers of Behavioral Neuroscience.

A new crustacean species found in Galicia

12 hours ago

One reason that tourists are attracted to Galicia is for its food. The town of O Grove (Pontevedra) is well known for its Seafood Festival and the Spider Crab Festival. A group of researchers from the University ...

Ants in space find it tougher going than those on Earth

13 hours ago

(Phys.org)—The results of a study conducted to see how well ants carry out their search activities in space are in, and the team that sent them there has written and published the results in the journal ...

Rats found able to recognize pain in other rat faces

13 hours ago

(Phys.org)—A team of researchers working in Japan with affiliations to several institutions in that country, has found that lab rats are able to recognize pain in the faces of other rats and avoid them ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Oct 09, 2009
The article does not say if the pigs could have located the food by scent.
not rated yet Oct 09, 2009
Probably not, if the control group looked behind the mirror rather than where the food was. If the pigs located it by smell, both groups should have had the same success.
Oct 09, 2009
This comment has been removed by a moderator.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.