I'd agree that a lot of our perceptual reality is self-generated -- as a glance through this site or the cog-sci or psychology literature will tell you, our thinking is riddled with biases, shaky interpolations, false memories, and various other deviations from an ideal model of the world. But by the same token there are substantial regularities in those deviations; as a matter of fact, working back from those tendencies to find the underlying cognitive principles behind them is a decent summary of what heuristics-and-biases research is all about. So I'd disagree that our perceptual worlds are unpredictable: people's minds differ, but it's possible to model both individual minds and minds-in-general pretty well.

As to your second clause, most humans do have substantial social needs, but their extent and nature differs quite a bit between individuals, as a function of culture, context, and personality. This too exhibits regularities.