It's not always easy to distinguish between human social interactions and the complex chemical interactions that underpin them. Just hearing a calming, familiar voice can alter a person's hormones in a beneficial way...and technology just gets in the way.
That's the finding of biological anthropologist Leslie Seltzer of the University of Wisconsin. She designed an experiment in which young girls aged 7 to 12 were first faced wit a stressful laboratory task, and then were allowed to receive reassurances from their mothers. Precisely how the mothers communicated varied - some were able to speak face-to-face, others talked on the phone, and still others could only send a text. Some of the girls had no contact with their mothers at all.
Seltzer and her team found that daughters who could hear their mothers - whether it was in person or over the phone - showed clear drops in their cortisol levels and a release of oxytocin. Cortisol is a hormone commonly linked with stress, while oxytocin is the so-called "love hormone" (a term not without its controversies). Basically, on a hormonal level, the presence of a mother's voice allowed the girls to instantly feel better.
As for the girls who could only receive a text message, they showed no release of oxytocin, and their cortisol levels remained so high that it was if they had never communicated with their mothers at all. There are a couple possible reasons for this. One is the evolutionary reason - speech has a long history in our species, and it makes sense that a mother's voice would be able to soothe their children, right down to a chemical level.
Of course, there is another possibility - the mothers might just be crap at text messaging. While the mothers were told to be as reassuring and loving as they could be in their texts, it's conceivable that they lacked the same intuition with text messaging that they do with speech, and that had something to do with it. It would be interesting to try this experiment again in, say, 2031, when the mothers involved would presumably have grown up using text messaging from a younger age than mothers today. Even so, I wouldn't bet against a mother's voice when it comes time for a rematch.