I recognize this in myself and it's been difficult to understand, much less get under control. The single biggest insight I've had about this flinching-away behavior (at least the way it arises in my own mind) is that it's most often a dissociative coping mechanism. Something intuitively clicked into place when I read Pete Walker's description of the "freeze type". From The 4Fs: A Trauma Typology in Complex PTSD:

Many freeze types unconsciously believe that people and danger are synonymous, and that safety lies in solitude. Outside of fantasy, many give up entirely on the possibility of love. The freeze response, also known as the camouflage response, often triggers the individual into hiding, isolating and eschewing human contact as much as possible. This type can be so frozen in retreat mode that it seems as if their starter button is stuck in the "off" position. It is usually the most profoundly abandoned child - "the lost child" - who is forced to "choose" and habituate to the freeze response (the most primitive of the 4Fs). Unable to successfully employ fight, flight or fawn responses, the freeze type's defenses develop around classical dissociation, which allows him to disconnect from experiencing his abandonment pain, and protects him from risky social interactions - any of which might trigger feelings of being reabandoned. Freeze types often present as ADD; they seek refuge and comfort in prolonged bouts of sleep, daydreaming, wishing and right brain-dominant activities like TV, computer and video games. They master the art of changing the internal channel whenever inner experience becomes uncomfortable. When they are especially traumatized or triggered, they may exhibit a schizoid-like detachment from ordinary reality.

Of course like with any other psychological condition there's a wide spectrum: some people had wonderful childhoods full of safe attachment and always had somebody to model healthy processing of emotions for them, some people were utterly abandoned as children, and many more had something between those extremes. The key understanding I've gained from Pete Walker's writing is that simply being left alone with upsetting inner experience too often as a child can lead to development of "freeze type" defenses, even in the absence of any overtly abusive treatment.

I suspect that using a combination of TV shows, games and web browsing as emotional analgesics (at various levels of awareness) is very common now in wealthy countries. This is one of the reasons I would like to see more discussion of emotional issues on Less Wrong.