I admit: I have frightened a horse before. *By accident*
Yes, and understanding horses can prevent you from frightening horses. Visit this page to understand Horse Language: http://ilovehorsies.wordpress.com/horse/horse-language/
But there is more to it. There are people who say they can speak the language of horses. I’ve actually tried some before…
When you see a horse (preferably a horse you know) be sure it doesn’t bite and is gentle when you first try this. Be very sure that it knows you are there. When petting it, gently blow into it’s nostrils. Make sure you aren’t suddenly blowing gently. Be sure to gradually blow. The horse will interpret this as “hi!” and blow gently back.