A colleague of mine took this photo in Nairobi. The sign is obviously marking aisle 12B in a grocery store. What is not so obvious is that the label on the sign, “Pasters”, should be “Pasta”. The error comes from interference. Interference is what happens when an adult learns a new language. The mother tongue interferes with the new language, causing errors.
In this case, there is a string of errors. First, Kenya (where the photo was taken) is a former British colony. So English there is influenced by the way the British colonists spoke English. For some of them, a word that ends in “a”, like pasta, is pronounced as though it ends in r. So pasta is pronounced pah-ster. One of my dear British colleagues always said “goner” for Ghana.
In the case of the sign, a Kenyan heard the “pah-ster” pronunciation then thought that the word ended in er and so wrote it “paster”. As there are many bags of pasta and many different kinds of pasta in the aisle, the person making the sign assumed that the word needed to be plural.
And that is how pasta became pasters.
This is an example of interference for the sounds in a language. But interference can also happen for grammar and even the meaning of words. I could tell some pretty embarrassing stories of mistakes I have made when learning languages that were caused by interference. I used the word I would have used in English and people responded with shocked looks or blushes.
Interference also inhibits understanding, not just speaking. My Congolese colleagues told me of a pastor who preached on the text “He who has the Son has life”. He explained that every married couple needed to have a son to have eternal life. The problem was that he was preaching from a Bible in a language other than his own mother tongue, and his mother tongue does not have a word that corresponds exactly to “the”. So “He who has the son has life” became “He who has a son has life”.