Self scanning store lanes boosts convenience - and theft.

— -- Stores are increasingly adding self checkouts, which can make it more convenient for many people to shop — and steal.

Walmart and CVS are among the chains adding self-scanning lanes. But at least two grocery chains — Albertson's and New England-based Big Y— have abandoned their self service moves. Both cited customer service as the reason, although Big Y says shoplifting played into the decision.

Theft — intentional or not — is up to five times higher with self checkout than when cashiers are working, says Malay Kundu, founder of Stoplift Checkout Vision Systems, which sells store video analytic software.

Kundu's company has seen people scanning their Starbucks as bananas, leaving their items in the cart or reusable bag instead of scanning them and overloading the bagging area so that un-scanned merchandise can be piled on without being sensed.

Still, most stores aren't ready to give up on self checkout and many will likely add lanes now that easier-to-use systems that also reduce the risk of theft are coming, says Joe LaRocca, National Retail Federation's senior asset protection advisor.

New "tunnel" scanners will allow shoppers to put everything onto a conveyor belt and have prices scanned automatically, even if on unmarked produce, says LaRocca. Newer self checkout systems are also more intuitive and can tell, for example, if items aren't placed on the belt. Besides, loss prevention experts are getting better at spotting this breed of shoplifter.

"There are ways to distinguish between someone who accidentally forgets to pay or intentionally moves the item so it isn't scanned," says LaRocca. "If you see the physical behaviors enough, you know it when you see it."

Self checkouts in North America will increase by up to 10% in the next few years, says research and advisory firm IHL Group. The biggest growth is expected at convenience, hardware and drug stores.

Self checkout lanes can reduce labor costs and improve customer service, especially for quick shopping trips. But they can backfire if shoppers have problems scanning their items, says Kurt Jetta of consumer analytics company TABS.

Big Y removed its self checkout lanes by the end of 2011 because of complaints about scanning problems and theft. But spokeswoman Claire D'Amour-Daley says the chain hasn't noticed a change in shoplifting patterns since it removed the do-it-yourself lanes.

"If they don't find one way to steal, they'll find another way," she says.