Tag Archives: brain development

Is Touch a Key Point of Human Social Development?

I am an extremely touchy person—my friends actually scold me from time to time because I don’t acknowledge the concept of “personal space”. I enjoy being in close contact to people and expressing my emotions through lots of physical movement, but that’s because I grew up in an environment that encouraged me to do so. Throughout my lifetime, I have come in contact with people who do not like being touched or in close contact with other people, and overall they seem to be more reserved in their expression and overall introverts. Despite my overwhelming nature, I have been able to befriend some of these people and they have told me that they never received much physical touch when they were growing up. So what I wanted to know was if there was a relationship between he amount of touch we received when we were younger and our overall social development.

According to Psychology Today, researchers in the United Kingdom released a study in October 2013 that confirms the importance of human touch to healthy brain development. They found that “a loving touch, characterized by a slow caress or gentle stroking increases the brain’s ability to construct a sense of body ownership and plays a big part in creating and sustaining a healthy sense of self.” However, the parameters of the study were not made available on the website, so I cannot be completely sure of the findings. The study conducted would most likely be either observational study or a survey and done over a time period of several months to a few years because nature of the data they are gathering. If it was an observational study that was conducted, the control group would have to be children that were born and then immediately given over to an adoption agency or foster home, an environment where there is little to no intimate human contact. Also, I would be interested to know what was the age range of children observed because there is probably a critical window of development where touch provides the most change.

So there is some evidence that touch helps brain development, but I wanted to find a randomized experiment that actually tested the relationship between levels of physical stimulation during early developmental stages and social disposition. One of the earliest studies on the benefits of touch was conducted in the 1920s by researcher Fredrick Hammett on rats. He reported that rats that were infrequently handled were more timid, apprehensive and high strung than the rats that had been “pet gently.” For the developing rat pup, mothers and litter-mates are the major sources of sensory input. A useful approach to evaluating the importance of this input is to remove it completely and observe what happens. Another experiment was conducted by comparing the adult behavior of maternally reared rats with those isolated in plastic cups, from postnatal days 4 to 20. Despite receiving comparable nutritional input, the pups raised in cups weighed less at weaning. Although this difference did not persist into adulthood, early deprivation did affect adult maternal and emotional behavior. Compared with maternally reared controls, isolate-reared rats were less attentive to their own offspring, performing fewer pup retrievals and spending less time licking and crouching over pups and spending more time digging, biting the cage, hanging from the top of the cage, eating and tail chasing. These behaviors suggest that the lack of early stimulation can potentially affect behavioral patterns regarding social interactions. Of course, correlation does not mean causation and reverse causality could be a potential option as well (the rats were socially mean which caused them to receive less touch), but the experiment seemed to be done well so I highly doubt it.

But then is there any hope for those who didn’t receive much contact as they were growing up? There was a second part to the study that took the rats that were the pups in cups were stroked with a warm wet paintbrush to simulate maternal licking. The minimally stimulated pups received 45 seconds of stroking twice a day to promote urination and defecation. The maximally stimulated pups received 2 min of full-body stroking five times per day. When the pups were studied as adults and the way they mothered their own offspring was examined, it was found that full-body stroking partially rescued the behavioral deficits of isolation, with the maximally stimulated pups exhibiting maternal behaviors of durations intermediate to those of the maternally reared and minimally stimulated pups. Thus, tactile stimulation can ameliorate some of the deficits resulting from isolate rearing in rats.

So there is some home for my introverted friends after all. They probably won’t see much benefit in it since they have survived this long, but that won’t restrain me from smothering them with love from now on.