Does Hugging for 20 seconds cause an Oxytocin spike?

Question

So I've been seeing this around a lot lately in various articles and "amazing fact" lists and even found one place that gives some sources PositivePsychologyNews but I can't seem to find the original source of the 20 second claim. The closest I found was in this study referenced in the above article which states... (emphasis mine)

Couples were seated on a loveseat in a quiet room and instructed to sit close together, holding hands if they felt comfortable doing so. They were asked to talk about a time they had spent together that had made them feel closer as a couple (2 minutes). They then watched a 5-minute segment of a romantic video they had previously seen. They then were instructed to talk for 2 minutes about a time when they felt close as a couple. During this time, couples were unmonitored and unobserved except when the experimenter entered the room to give instructions. At the end of this session, partners stood for a 20-second hug.

Perhaps I'm misunderstanding, but that seems like the 20 second hug wasn't isolated as the cause alone. Have there been any other studies that suggest the 20 second time frame? Did I miss something in that one? Some of the sources listed are behind a paywall sadly.

Answer 1

The trial was based on opposite sex couples only. There were a range of activities undertaken between measuring oxytocin levels, not just hugging, so hugging cannot reasonably be concluded to be the causative factor in change oxytocin levels. Additionally, there were higher oxytocin levels in those in loving relationships.The researchers, led by psychologist Dr Karen Grewen, wrote in Psychosomatic Medicine: "Greater partner support is linked to higher oxytocin levels for both men and women. The study reinforced research findings that support from a partner(in this case presumed to be a hug from a loved one) can have beneficial effects on heart health.Dr Charmaine Griffiths, spokesperson for the British Heart Foundation, said: "This growing body of research only goes to highlight how important social support is for everyone, not just those in a relationship."