I Went Into Primark With a Strict £50 Gift Card Budget. I Left Spending My Own Money Too: How Information Systems Engineered Your Last Impulse Buy

By Khadijat Othman | Innovation and Information technology

It was a birthday gift. £50 loaded onto a Primark gift card, and I had a plan: one good leather jacket, maybe one other small thing. Simple. Controlled.

Forty minutes later I was at the checkout with pajamas, 4 dresses, three “essentials,” and a total that had blown past the gift card. I was tapping my own bank card to cover the rest, and somehow I still felt like I won.

That feeling? That is not an accident. That is an information system (IS) working exactly as designed.

The Store Is the Software

Here’s what most people do not realize: a physical shop like Primark is not just a building full of clothes. It is a data-driven environment built to influence every decision from the moment you walk in.

The “£7 pyjamas” sign sticking up from the rack is not just a price tag. It is a trigger, placed based on footfall heatmapping data that tells the store exactly where your eyes go, how long you linger and which zones convert browsers into buyers. The layout, the signage, the routing that pulls you past twelve other sections to reach the basics. None of it is random.

Retailers use Point-of-Sale systems, footfall sensors, and transaction data to build detailed models of how customers move, pause and spend. That data feeds directly into store design, pricing and promotional placement. The “50% off” posters are positioned where the data says you are most likely to stop walking and start picking things up.

“Girl Math”, But Make It Systemic

I have a theory: institutionalized girl math. The logic goes: everything is so cheap that buying more still feels responsible. A £5 dress is practically free. Four £5 items that are all 50% off is only £20. You are basically saving money by spending it.

Not irrational thinking. It is a predictable psychological response to low-price anchoring. Retailers know exactly how to trigger it. Research on impulse buying behaviour shows that perceived value, not actual price, is what drives unplanned purchases. Primark’s entire IS infrastructure is built around manufacturing that perception at scale.

I did not forget about the leather jacket because I got distracted. I forgot because the system guided me somewhere else first and once I was in the £5 zone, my original plan became irrelevant.

So What Do We Actually Do?

Awareness alone does not fix it. Knowing a system is designed to influence you does not make you immune. What it does is shift the responsibility.

Retail behavioural analytics is a legitimate, growing industry. Stores invest in it because it works. As consumers, the least we can do is walk in with a list and notice the moment we start rationalizing a £4 item we never came for.

The jacket is still there. It may or may not even be there next time. The system, however, is counting on you forgetting that.