The Washington Post reports that a handful of colleges recently dropped the ubiquitous dining hall tray, and found that wasted food decreased by as much as 25-30% as a result.

An excellent result from so small a change, and one that makes intuitive sense: without a tray to pile upon, the amount of food people can carry apparently much better matches the amount they can actually eat.

But that glosses over an interesting question: why do people take more than they want to eat, even if they can carry it? Because, it turns out, they have no idea how much they want. Research has increasingly shown that, across the board, we’re terrible at assessing up front what’s going to make us happy at some point later, even if that just means determining how much food will make us feel pleasantly full fifteen minutes from now.

And, I think, it glosses over a second, even more interesting issue: we hugely underestimate the degree to which our tools affect our behavior. While scientists may not have previously researched trays, they’ve repeatedly researched plates, demonstrating, for example, that manipulating the size of plate on which we serve food changes the amount of that food we eat before feeling full; smaller plates lead to eating smaller portions, though with people thinking they’ve actually eaten more.

Of course, it isn’t just dinner plates and dining hall trays. Indeed, nearly all of modern life seems to operate at the same juncture of manufactured stuff and unclear self-assessment; thus, we make things, which in turn re-make us. Which is to say, we create technology (say, a plate) to assist us with an ill-understood instinctive behavior (eating food), and then find that the technology has led to unexpected consequences in the very behavior itself (how much of the food we eat).

For the behavior of communication, we’ve at least long acknowledged that we’re shaped by our tools – it’s been more than 45 years since McLuhan pointed out that the medium is the message. But as more of our life becomes mediated by technology – how we share with friends, how we find our mates – the effect becomes exponentially greater. We’ve thrown ourselves into this crazy experiment without much thought, and we plow ahead, increasingly unthinkingly, shaped by our tools, unable to self-assess or future-predict, each brand new day.