All ears: How horses communicate
4 August 2014 Last updated at 19:11 BST
A study in horses suggests they pay close attention to the direction another's ears are pointing in order to work out what they are thinking.
Researchers from the University of Sussex say the animals' swivelling ears have become a useful communication tool.
Their findings are published in the journal Current Biology.
Here, lead researcher Jennifer Wathan explains how, in her experiments, looking at a picture of another horse, affected the animals' decision-making.
Footage courtesy of Jennifer Wathan, University of Sussex