Instant messages are ubiquitous and convenient, but something primal may be lost in translation.

When girls stressed by a test talked with their moms, stress hormones dropped and comfort hormones rose. When they used IM, nothing happened. By the study's neurophysiological measures, IM was barely different than not communicating at all.

"IM isn't really a substitute for in-person or over-the-phone interaction in terms of the hormones released," said anthropologist Leslie Seltzer of the University of Wisconsin, lead author of the new study. "People still need to interact the way we evolved to interact."

In earlier work, Seltzer's team showed that both phone conversations with mom and face-to-face talks triggered similar hormonal responses: A drop in cortisol, which is generally linked to stress, and a rise in oxytocin, which is linked to pleasure.

For the latest study, published in the January issue of Evolution and Human Behavior, they wanted to identify the source of that comforting. Maybe it's something mom says, in which case the medium of communication shouldn't matter at all – or maybe it's something in the sound of her voice.

"Would this still work if we took out the tone, if we took out the verbal cues, and all we had left over was the content of the message?" said Seltzer.

The researchers recruited 64 girls between the ages of 7 and 12, pre-screened to remove anyone with histories of extreme family difficulties or poor maternal relationships. The girls then underwent a standard routine for inducing stress in the laboratory: They were asked to solve difficult math problems in front of three unknown adults who watched them impassively.

After finishing, the girls were assigned to one of four groups. One didn't talk at all to their mothers. Another group talked by phone, another had a face-to-face conversation, and another communicated by instant message. The researchers then measured their cortisol and oxytocin levels, and compared them to pre-test measurements.

As expected, girls who heard their mother's voice, either in person or on the phone, were consoled. But among girls who used IM, hormone levels barely changed. Translated into words on a screen, mom's words seemingly lost their comforting power.

According to Seltzer, the results suggest that mom's voice – its tones and intonations and rhythms, known formally as prosodics – trigger soothing effects, rather than what she specifically says.

However, it's also possible that IM altered conversational dynamics. Maybe moms who heard their daughters' voices were better able to detect stress and respond to it. On a screen, "I'm fine" is a fairly one-dimensional statement. Heard aloud, it can convey something very different.

"It doesn't matter how many smiley faces you put in your IM. It's not going to have the same effect as talking in person," said Seltzer.

Image: Andrew/Flickr

Citation: "Instant messages vs. speech: hormones and why we still need to hear each other." By Leslie J. Seltzer, Ashley R. Prososki, Toni E. Ziegler, Seth D. Pollak. Evolution and Human Behavior, Volume 33, Issue 1, January 2012.