On Accident Versus by Accident

Some of the most difficult questions I get are from non-native English speakers who want to know why we use a particular preposition in a specific phrase. Why do we say I'm in bed instead of I'm on bed? Do people suffer from a disease or suffer with a disease? Are we in a restaurant or at a restaurant? I’m a native English speaker, so my first thought is usually something like, “I don't know why; in bed just sounds right,” and sometimes both options are correct.

Here's a question I hear regularly:

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Sometimes when I get questions like this I can find an answer, and sometimes I can't. In this case, I hit pay dirt!  I was lucky enough to find an entire research paper on the topic, published by Leslie Barratt, a professor of Linguistics at Indiana State University. 

Whether You Say ‘On Accident’ Depends on Your Age

According to Barratt's study, use of the two different versions appears to be distributed by age. Whereas on accident is common in people under 40 or so, almost everyone who is older than that today says by accident. It's really amazing: the study is 10 years old now, but if you assume usage hasn’t changed in the last 10 years, the results mean people born after 1995 are more likely to use on, people born between 1970 and 1995 say by accident more often than on accident, but still use on accident a lot too, and then people born before 1970 overwhelmingly prefer by accident. It looks like a directly age-related change in the way people are saying this phrase.

Reddit Comments Seem to Confirm the Study Results

Barratt’s study is 10 years old and it was relatively small, surveying only about 280 people, but I also found some recent evidence that on accident is relatively common among young people. The people at the website FiveThirtyEight made a tool that shows the frequency of words and phrases in more than a billion Reddit comments. It’s a lot like how you can search Google Books with Google Ngram, but it’s for Reddit, so instead of seeing how words are used in published books, you can see how words are used on the Internet, or at least on Reddit. 

Reddit users tend to be young (91% are younger than 35), so you would expect it to be a mix of people who prefer on accident and people who somewhat favor by accident. What you see is that Reddit commenters use by accident about three times as often as on accident, but that’s still a lot of people using on accident.

Why Would People Change What They Say?

An interesting conclusion from Barratt's paper is that although there are some hypotheses, nobody really knows why younger people all over the U.S. started saying on accident instead of by accident. For example, there's the idea that on accident is parallel to on purpose, but nobody has proven that children all across the country started speaking differently from their parents because they were seeking parallelism. 

Neal Whitman, a linguist and regular Grammar Girl contributor, speculated that the change could have come from a mishearing of an accident—for example, children mishearing It was an accident as It was on accident. But he also admits that this theory also doesn’t explain why on accident seemed to suddenly become the norm in people born after 1995.

Although I have no proof, I suspect that it must have something to do with nationwide media since it is such a widespread age-related phenomenon. Barney & Friends started airing in 1992, so maybe it's Barney's fault! Or there have been 19 seasons of Pokemon since 1999, so maybe Pokemon is to blame. If you know of a children’s show that uses on accident a lot and fits the timeline, let me know.

Writers Are Using ‘By Accident’ Less Often

Although Barratt’s study was about spoken English, I did do a Google Ngram search to check how on accident and by accident have been used in published books over the years. The use of on accident overall is very low compared to by accident, but it peaked in 1940 and has gradually fallen since.

I did see a small but steady decline in the use of by accident since around 1900, but it’s hard to say what that means beyond simply saying that it is a trend. Writers seem to be using by accident less often in general. Maybe children are being exposed to it less? But the drop is gradual. It’s not something so dramatic that it makes me think children would never read the phrase. 

At this point, I think all we can say is that the change is one of those language things that happens sometimes.

Finally, although usage guides state that on accident is an error, and Shelly from Texas asked me to do what I can to ban on accident, Barratt found that there is no widespread stigma associated with saying on accident. In addition, it seems to me that as those kids who say on accident grow up (some of whom are even unaware that by accident is an option, let alone the preferred phrase of grown-ups) on accident will become the main, accepted phrase. By that time, there won't be enough of us left who say by accident to correct them!

Note, 2022: You may enjoy this fabulous story of a Minneapolis news station that unearthed video footage of Prince as a school boy, in which the newscaster emphatically states they found it "on accident."