Horses and ponies are herd animals and used to living as part of a group, feeling secure in the company of other equines and familiar surroundings. They are timid by nature and their natural reaction to danger is to flee.
The horse's sense of hearing is very acute and its sense of smell is also good enabling it to sense danger some distance away.
A horse is a very sensitive animal and able to sense the feelings of those nearby particularly hesitation, fear, confidence and anger.
Horse Body Language
The body language of a horse and how horses indicate their feelings.
Horse intelligence and how horses learn.