Sometimes, your host does things which cause him to be so embarrassed that he doesn't know what to do short of posting about it and letting his readers join in the fun. This is one of those moments.
Today happened to be the birthday of Maternal Grandmother SC (henceforth, MGSC), and so to celebrate, Mom SC brought her up to a regional mall not far from Chez SC to spend the day, concluding with dinner with family. A sensible plan for a pleasant day.
While a gentleman never asks the age of a lady, nor discloses it if he happens to know anyway, suffice it to say that walking is no longer foremost among MGSC's talents. In order to facilitate a day of traipsing around malls, Mom SC therefore decided to surprise MGSC with a device she mistakenly believed to be a wheelchair. In fact, it is something called a "rollator", or a wheeled walker. A product similar to the one actually bought can be seen here; SC is unable to provide a more reliable picture for the reader's edification because the tag identified the walker as a product of "Dr. K.", a company which apparently has no Internet presence, nor is commonly sold online. However, the picture is similar enough to give the reader an excellent idea of what followed.
Although the rollator has four wheels, only two of them are actually able to turn for the purpose of changing directions. They happen to be the two wheels located under what looks like, from the perspective of someone who thinks it's a wheelchair, a backrest for the seat. Mom SC reported that MGSC had great difficulty using the wheelchair; would SC mind taking a look?
After inspecting the device, your host "discovered" that in order to successfully change directions, it helped to back up while turning in the opposite direction of the one you want to go forward in. Much like driving in reverse, really. A few minutes of practice sufficed to give SC reasonably impressive skill in "driving" with the rollator. MGSC found the whole thing rather counterintuitive, though, and is likely to return it.
When your host returned home, he discussed it with Mrs. SC (who is presently out of town, and who otherwise would have prevented this from happening). After SC explained to her the difficulty of a wheelchair that had to go backwards to turn, she started to suspect that the problem wasn't the chair. Why, after all, weren't the steering wheels mounted in front? It all came together when your host explained that mounting the chair in a way that would put those wheels in front would require lifting the rider's legs notably higher than most elderly people can easily tolerate.
That's when Mrs. SC realized that your host wasn't describing a wheelchair, he was describing a walker! Under no circumstances should anyone try to ride one of these devices; instead, the "backrest" is actually a handlebar, and the seat is meant as a convenience for use when the user gets tired. Why, then, is it equipped with handbrakes? Not to stop someone from riding too quickly, but to stop it when they want to walk around the side and sit down. Needless to say, Mrs. SC had quite a good laugh over SC's total inability to figure out the proper use of the rollator.
There is a linguistic lesson in this, or at least a psychological one. As with a Rorshach test, given the outline of a novel object, your host imposed on it the label that most closely corresponded with similar objects in his previous experience. Once the rollator had been characterized as a "wheelchair", he similarly assigned names to the parts which followed naturally from a belief that the object was a chair, and not a walker. Thus, the handlebar became a chair back, and the handles above the brakes became armrests. Only, the back wasn't a back, and the armrests weren't armrests. But SC had such strong associations between the form of what he was seeing and other wheelchairs, that he simply could not see a walker until someone who knew better told him so.