Sweets and batteries by the tills - isn't that the way of it? And Good Housekeeping, too. I often find myself queuing for the checkout while chewing on a great wad of spearmint gum and experimentally touching the terminals of a nine-volt Duracell battery with the tip of my tongue. Under such a sensory overload, an article about Katie Price's latest marital schism acquires a giddy surrealism. But then the checkout operative beckons me forward - I replace the magazine and the batteries, then still my jaw, so evading once again the nefarious manipulations of the merchandisers, whose objective is to substitute the instinctive herd behaviour of a bovine consumer for my capricious will.

Supermarkets are the abattoirs of capitalism and we are but so many cattle, driven along brightly lit aisle after aisle until our credit is electrocuted. True, some people hold out and shop locally, discussing the cut of a meat or the bloom of a peach for hours on end with homely, red-cheeked butchers and flaxen-fringed costers - but who are these folk, for I do not know them. Then again, some shop online - although not enough. The story of Ocado, floated recently on the stock exchange for a staggering amount, despite being barely profitable, could stand as an extreme instance of merchandising itself: send products (refrigerated Mercedes vans) scooting up and down the aisles (residential streets) for long enough, and people are bound to buy them.

Heidi high

But by far the majority of us cows graze at the Big Five supermarkets, and this means that, for a significant portion of our lives, we are in a peculiarly divided state of mind, for, at the precise moment when we most compellingly feel ourselves to be exercising a choice, we are in fact being comprehensively manipulated. The sweets and batteries are by the till, but fresh fruit and veg are by the entrance so as to give the entire retail barn that wholesome natural vibe. When I shop at my local supermarket, I often feel as if I'm walking into an Alpine meadow - which is why I frequently find myself buying a new dirndl, a fondue set and a CD of yodelling, all the better to seduce Heidi with.

Actually, with fantasies like that, I'd do well to keep my von Trapp shut, but in my experience fantasy is the only way to protect yourself against this walk-through brainwash. You may set out intending just to get some chives and a support stocking, but inevitably you end up with the Yugoslavian Riesling, the 24-inch flat-screen TV and . . . well, chocolate isn't really a purchase per se, now, is it? It's more like self-love wrapped in gold foil.

Getting trolleyed

The most disturbing aspect of supermarket madness is that it's all scientifically determined: from the second the electric doors shush open, every thought you have has been graphically plotted. When I studied economics at university, the theory that most appalled me was the notion of revealed preference, which proposes that consumer preferences are transitive - from one bundle of goods to another - dependent on price and revealed by acts of choice.

Once an individual's pattern of consumption has been determined, a so-called "indifference curve" can be plotted, which demonstrates how his or her demand will fluctuate between equally preferred bundles of goods. I've no doubt that supermarkets situate "gondolas" and shelves so as to maximise sales by the positioning of "bundles" of goods that they know consumers will perceive as more desirable.

This is why the supermarkets have got bigger and bigger. Meanwhile, we have got stupider and more powerless. In perhaps a millennium or two, humanity will have evolved fully into Homo shoppingtrolleyus, a lumbering beast on castors, with four stomachs, one loyalty card and a bar code across its forehead. Until then, we are doomed to being compelled to buy value packs of Quavers against our will.

Or are we? Why not do as I do? Enter the supermarket as if plunging into a Zen trance, allow yourself to experience the giddy whirl of choice as if it were a revolving mandala - then piss off without buying anything. Or else, undertake long treks to remote supermarkets in order to buy one item. A couple of years ago in Chicago, I walked nine miles from the Loop to the Near North Side to get a pair of socks at Wal-Mart. Sure, it was a crazy thing to do - but it was my own madness, not the crowd's.