I'm not sure why I continue to do it. Each time, I become unspeakably irritated, sometimes verging on violent acts. Yet still I find myself drawn to them. "Them" being the self-service checkouts at the Evil Empire which is Tesco.

I think perhaps it is the fulfilment of my childhood ambition, which was to be a checkout girl. Yes, the pinnacle of achievement when I was a pigtailed youngster was to reach the dizzy heights of a cash register, the future I envisaged for myself was clothed in a polyester tabard and seated on a swivel chair. With such ambition, it's hardly surprising that my adult life has not seen me exactly hammering on the doors of professional success.

Back then, of course, cash tills were far more fun. Fewer digital bleeps, more mechanical clunking and whirring; sounds which could not be accurately emulated at home with a standard calculator blu-tacked onto a bedside cabinet, the top drawer of which would be filled with toy money. A better imitation was provided by the printing calculator mum would sometimes bring home from work if she needed to catch up on some figures. It made pleasingly authentic sound and, of course, produced a receipt - vital if you wanted to be "in character".

At the age of seventeen, I finally got to experience the reality of life as a checkout girl, although only at weekends and not in a supermarket. Over the orange tabard of Sainsbury's, I chose the green dungarees of Homebase, a DIY store. The tills were not, however, the noisy mechanical ones at which I had gazed adoringly as a bright-eyed child. These were electronic, computerised and required the entry not of a price, but of a six-digit POS number (I can still remember the code for Baby Bio plant food which was strategically placed at the checkout and provided many a customer with a last minute, unplanned purchase). The use of barcodes was not yet de rigueur.

Whilst I would have happily remained at that little desk, keying in POS numbers and accepting payments throughout my career at the DIY store, the powers-that-be decided that I was too "good" and "promoted" me to the Information Desk. The fact that I would be allowed to make tannoy announcements went some way toward compensating for being dragged reluctantly away from the checkouts, but I still gazed longingly at those numbered desks, where life was easy, predictable, rhythmic...

And so it is that I always find myself drawn to the self-service checkouts, eagerly proffering barcodes to the mysterious, laser-ridden window, awaiting the confirmatory bleep of acceptance. But what temperamental fellows these things are! If I even dare to place my purse in such a way that one tiny part of it touches the conveyor, I am duly scolded by the faceless, bodyless, digital voice. And woe betide me if I attempt to hang my reusable bag on the hook so that I can easily pack my items as I go: "Unexpected item in the bagging area!" she shrieks.

If I were more assertive, I would shriek back: "It's a bag, in a bagging area. Deal with it, bitch!" But no. I resignedly remove my bag, place my items "naked" in the so-called bagging area and only after finishing my transaction am I free to transfer the items into my bag whilst the next customer looks on, disapprovingly.

The experience is always unsatisfactory and yet, like a moth to a flame, I return. Time and time again.