Michael Hassard, a former engineer for NASA, hikes and camps, takes long motorcycle rides, mows his lawn, fixes leaky faucets, and loves football.

He also cries—quite often: Whenever the Battle Hymn of the Republic is played or if the checkout clerk at Wal-Mart says, “God Bless You;” when the country song about the guy who fixes a tire and refuses payment comes on; and once when he donated some winter coats his children had outgrown to a family he knew from church.

“I keep tissues handy at all times,” says the 44-year-old engineer for an oil and gas company, who lives in Houston.

Meet the Highly Sensitive Person, or HSP—someone who responds more intensely to experiences than the average individual. Experts say HSPs process both positive and negative information more thoroughly, and so they can easily become overwhelmed by stimuli. They are acutely aware of sensations, whether of taste, touch, sound or smell. And they are particularly sensitive to emotions—their own and those of others.

Research studies show that about 20% of the population fits into this category, and the trait is found in the same numbers in men and women.