Dear Doctor: How guide dogs do their work


Q.  You said in a recent issue that guide dogs help blind people by remembering that a green light means go and a red light means red, but I thought dogs didn’t see green and red all that well and were better able to distinguish blues and yellows. Wouldn’t that make their ability to help people cross the street by the color of traffic lights rather iffy?

Spencer Blau
Hollywood, Florida

Dear Mr. Blau,

A. You raise a good point. We misspoke, as differentiating between colored lights is not how dogs help blind people cross the street. In fact, lights are not really part of it. Instead, a blind person and a guide dog work together using an entirely different system to insure safe street crossings. Kim Charlson, treasurer of Guide Dog Users of Massachusetts and herself someone with a guide dog, explains it as follows.

“At a crosswalk, a guide dog responds to a blind person’s cue to walk when a) the person has listened carefully to the parallel traffic and hears no cars turning right on red and b) the audible pedestrian signal, if one is there, has indicated that it is the pedestrian’s turn to cross. The blind person will then say “Forward,” and if all appears clear, the guide dog will step forward and move across the street. The only time a guide dog will refuse the “Forward” cue is if she (or he) detects with her vision that there is something that could pose a danger to the ‘team’ such as a quiet hybrid vehicle that the blind person may not hear.

“This is called intelligent disobedience,” Ms. Charlson explains, “and is an amazing aspect of a guide dog’s work. This ability relies on a dog’s intellect, her senses, and her devotion to her handler.

“But at no time is the work of a guide dog/human partnership ever totally dependent on the dog. It is the blind person assessing her environment, making the decision, and then relying on the dog to do her part to complete the crossing correctly. The entire time, the dog is focusing on the destination — the other side of the street — but keeping an eye on all traffic to make sure she doesn’t have to perform any emergency maneuvers to safeguard her handler. It is the true example of teamwork.”

Ms. Charlson adds that “sometimes distractions happen. Dogs are not perfect. But in my opinion, guide dogs are about the most perfect creatures in the world!”


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