A study by consumer group Choice found that electronics, confectionary and beauty products bought from airport duty-free outlets were more expensive than the same goods bought from regular retailers. Despite that fact, the combination of a free hour or more pre-flight plus the lure of so-called "bargains" proves irresistible. Travellers are routinely seduced, and rent from duty-free outlets is a lucrative income stream for airports the world over. Psychology has come to play an important role in the duty-free area of the terminal. Rather than retail outlets side-by-side, as in Singapore's Changi Airport, a more effective arrangement is the chicane-style layout that forces travellers to walk in a winding path between them, as experienced in Sydney International Airport. A study by aviation consulting group InterVistas found that duty-free shops arranged in a serpentine configuration achieve sales up to 60 per cent higher than those in a more conventional pattern. Ikea has been using the same principle for years, and who walks out of an Ikea shop with just the item they came in intending to buy?