Humans are self-correcting organisms. It is sometimes amazing how long it takes us, but once we recognize a problem or a mistake, solutions often come quickly. As a teacher, I try to give children time and space to correct themselves whenever possible. They are happier when they figure it out themselves. But sometimes I need to give a little help.

Public domain digitally-altered photo from publicdomainpictures.net, Dawn Hudson
In language, we tend to correct each other frequently, whether we are children or adults. If we say “fork” when we mean “comb,” the person we are speaking to is likely to say, “You actually comb your hair with a fork?” We will quickly correct ourselves and say “comb” if we already know that word. If we don’t, our partner is likely to tell us, “That’s a comb, not a fork.” With a little repetition, we learn a new word. On the other hand, if we keep saying “fork” for “comb,” our friends will learn what we mean, and we may keep using the alternate meaning until we experience enough misunderstandings with strangers to adopt their word.
One common mistake is a failure to observe a difference that turns out to matter. When we categorize things, we group things that are not in fact identical. Grouping is more arbitrary than we might think. Forks and combs can actually look quite similar, and if we don’t consider their different functions, we might think they are the same thing in different styles. Once we have have made this determination, we carry the preconception that things that have teeth like forks are in fact forks.

“Backyard limes” by Wtstoffs at en.wikipedia – Own work. Transferred from en.wikipedia to Commons by User:Smooth_O using CommonsHelper.. Licensed under Public domain via Wikimedia Commons.
Take lemons, for example. They come in different sizes, shades of yellow and green (especially when unripe), different weights, different degrees of softness, and different degrees of sourness. In many Spanish-speaking locales, lemons and limes are apparently considered the same fruit, as they only have a single word for both of them: limón. Personally, I find them to taste different, but then, we call lots of things melons, and different varieties of those have different flavors, too.
Imagine a native English speaker’s confusion when she asks for limón for her tea and gets a lime. Then imagine her waiter’s confusion when she complains! She may be thinking the waiter is stupid, while the waiter is thinking that if she had wanted a limón amarillo (yellow), she should have asked for one in the first place. Sooner or later, if she stays in that area, she will figure out that she has to include the color, because everybody there seems to use the same word for either, and the green ones are more common. No one has to teach this to her explicitly because she will figure it out anyway. If she had been given a test on this word in a Spanish school, she might well have picked the picture of the grapefruit instead of the lime and gotten the question marked wrong.
A recent experience with my father’s home care assistants provides another example. They consistently failed to distinguish between two types of his dishes: saucers for cups and small bowls. Invariably, they would mix them into the same stack on the shelf when they unloaded the dishwasher, in spite of there being enough room to have two stacks. All other types of dishes would be separated. Once I figured out what they were doing, I could predictably find small bowls under saucers and vice versa, so I didn’t think it worth correcting. Besides, I was amused.
Each saucer had an indentation in the middle to hold the cup that went with it, while the inside of each bowl was completely flat on the bottom and the sides were a little higher. I grew up using these dishes and thought the difference was obvious.
This morning I noticed that the saucers and small bowels had been put in separate piles. Eureka! She figured it out! Then I remembered that my father had put the dishes away last night himself. Oh well.
The next time I run the dishwasher, I will try leaving a clean saucer and a clean bowl on the shelf. Will she see them as the beginnings of two separate piles, or will she combine them into one? Once she sees the difference, will her perception be forever changed?