I was recently interviewed by journalist Lisa Kanarek on why some people laugh at inappropriate times. In business, that might be when someone is told that a coworker has been passed over for a promotion or laid off. The expected response would be empathetic sadness, not laughter.

The journalist had observed this surprising behavior from someone when she shared bad news about a mutual friend, and wanted to better understand how a nice person could react so coldly. One reason is that laughing is a biological coping mechanism. Research shows that when someone feels overwhelmed or is experiencing strong anxiety, laughter acts to suppress stress hormones, like adrenaline and cortisol.

So how can you tell if the laughter is a result of stress or insensitivity? Here are some nonverbal cues that will help you:

LISTEN – a nervous laugh sounds different than a joyful laugh. Don’t forget that vocal patterns are also nonverbals. The nervous laugh comes from the throat or nasal area instead of from the stomach, like a belly laugh.

LOOK – pay attention to fleeting nonverbal cues. You might notice a “microexpression” of a quick frown that comes and goes just before or after the laugh. Or you may observe a closing of the eyelids that lasts longer than a normal blink. Notice whether their chin is tilted up or down. The chin tends to lift up with joy and turn down when feeling anxiety and low confidence. To avoid making a false assumption about what the person is really feeling, you want to listen and look for clusters of nonverbal cues, not just one signal.

Have you ever had a situation where someone laughed inappropriately? What happened?