Starbucks.com Considering a change to your company's logo? Tread carefully.

Earlier this year, Starbucks announced a dramatic change in its logo: No longer would the Starbucks name and the word "coffee" appear in the logo. Instead the mermaid image would increase in size.

The reaction from Starbucks fans was fierce and swift. As Reuters reported:

"Who's the bonehead in your marketing department that removed the world-famous name of Starbucks Coffee from your new logo? This gold card user isn't impressed!" wrote one customer who identified herself as MimiKatz.

Back in October, the GAP's proposed logo change caused so much ire among customers, the retailer was forced to reverse itself and announced days later it was sticking with its old logo.

Too many companies fail to fully understand that a logo is a symbol of the relationship between the brand and the customer. This symbol represents a shortcut to purchase that makes customers feel comfortable in buying because they know what they are getting.

Neuroscience helps explain why. Read Montague, a neuro scientist at the Baylor College of Medicine, scanned the brains of volunteers as they drank samples of cola. When they were not identified, there was no preference. When shown the Coca Cola logo, their brains showed a decided preference for Coke irrespective of the cola they were drinking.

What scientists have found is the brain takes short cuts when it processes information. The more it recognizes a symbol with which it is comfortable, such as the logo of a preferred brand, the quicker it makes a decision with less anxiety. Making changes disrupt the comfort zone.

This is why the most loyal customers - the ones with the closest relationship with the brand - are often the ones that are most upset when companies make changes to their logos.

Does this mean that logos should never be changed?

No. But there should be very good reasons for doing so. Here are three:

1. The image is damaged.

After the Florida Everglades plane crash, ValueJet became AirTran. It makes sense to change the logo (and name) if the company has had its reputation so deeply damaged that the customers' perceptions are fundamentally altered. Should BP change its name due to the Gulf oil spill? Perhaps.

2. The company has changed fundamentally.

If the business has shifted direction, the logo may no longer be presenting the right image. Nokia started out as a paper mill in 1865 along the Nokia river. They added rubber and other products along the way, with their first portable phone being introduced in 1984. As their business evolved, their logos changed to reflect this evolution.

3. The logo has reproducibility problems.

Apple's early multi-colored apple logos looked awful when copied. Their target audience also changed from the late '70s and early '80s when they only sold computers mainly to the education market. So their logo evolved into a single color apple.

How social media changes the equation

Too often logos are changed because new executives want to make their mark on the company, they want to give the brand an updated look, or the company has a problem unrelated to its branding that they want to fix. I don't know if this was the case with Starbucks or Gap, but they didn't have a compelling reason to make a change.

What's worse, they made the changes without consulting their most loyal customers. In the era of social media, companies can-and should-obtain quick feedback from their most fervent fans about logo change. Those that don't risk eroding this bond and causing an accelerated negative word-of-mouth pyramid and a publicity headache.

At least, the Gap listened. To date, Starbucks has not been swayed by complaints. Should they be?

What do you think?

This post originally appeared at BNET.