In the 40s, the Dutch zoologist Nicholaas Tinbergen did a series of experiments with newly hatched gulls and other animals, to show that their instinctive behaviors were in response to specific kinds of stimuli. Most famously, a red dot on a wooden board would cause the herring gull hatchling to start pecking at the dot; the hatchling’s instinctive behavior was confusing the dot with the one on an adult gull’s beak, and the pecking behavior was the way the babies elicited feeding from their parents. (Mmm….regurgitated herring.)
Tinbergen called these stimuli “releasers,” because they released the “fixed action pattern” of instinctive behavior. He also found that when he made the dot on the board larger or brighter than it would naturally be, he got an exaggerated behavior; he called these ultra-strong stimuli “superreleasers.”
It strikes me that the mass media will naturally select for stimuli that are superreleasers of various kinds, in competing for audience’s attentions. Most obviously, children’s cartoons feature brighter colors than found in nature, characters with extra-large eyes, etc. Toy advertisements and cereal boxes are obviously carefully chosen to draw and keep attention. Adults are presumably succeptible to their own kinds of superreleasers.
This raises an interesting question about what, from a developing child’s brain’s perspective, the “environment” really is. That is, it’s almost certainly going to be disproportionately composed of the stimuli that are best suited to attract attention. But there’s a lot more commonality across individual kids’ environment in the kinds of mass media superreleasers they’re exposed to than in what we normally discuss as their “home environment.” Buzzfeed pretty much made its name by endless “30 Cereal Boxes You’ll Remember If You Grew Up In The 90s” articles, which work precisely because everyone not only saw the same cereal boxes but remembers them. The ephemera of pop culture aren’t all that ephemeral precisely because they were selected through deliberate effort and the natural selection of the marketplace to stick in our brains.
When you read in various behavioral genetics studies that an absurdly high percentage of many child outcomes can be explained by genes, it would seem to say something about the fundamental homogeneity of child environments in rich countries, perhaps even more in the superstimuli that children are most attuned to than in the physical conditions or familial structures of their homes.