Linguistic capture errors

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Back in 2008, Arnold Zwicky described a category of typos that he called  "completion errors":

…a "completion error", a typo that results you start writing or typing a word and then drift part-way in to another word.  I do this all too often with -ation and -ating words — starting the verb COOPERATING but ending up with COOPERATION, for instance.  And several people have reported on the American Dialect Society mailing list that their intention to type LINGUISTS frequently leads them into LINGUISTICS, which then has to be truncated.  (This discussion on ADS-L followed my typing "original Broadway case", with CASE instead of CAST, and commenting on it.) 

26 years earlier, David Rumelhart and Donald Norman used the term "capture errors" for this phenomenon ("Simulating a skilled typist: A study of skilled cognitive-motor performance", Cognitive Science 1982:

This category of error occurs when one intends to type one sequence, but gets "captured" by another that has a similar beginning (Norman, 1981). Examples include:

efficiency – > efficient
incredibly – > incredible
normal – > norman

They further cite Donald Norman, "Categorization of action slips", Psychological review (1981), who wrote about "capture errors" of a more general type:

Capture slips. A capture error occurs when a familiar habit substitutes itself for the intended action sequence. The basic notion is simple: Pass too near a well-formed habit and it will capture your behavior. This set of errors can be described by concepts from the traditional psychological literature on learning—strong habits are easily provoked. […]

[C]apture errors have a certain flavor about them that set them off. Reason (1979) described them in this way:

Like the Siren's call, some motor programs possess the power to lure us into unwitting action, particularly when the central processor is occupied with some parallel mental activity. This power to divert action from some intention seems to be derived in part from how often and how recently the motor program is activated. The more frequently (and recently) a particular sequence of movements is set in train and achieves its desired outcome, the more likely it is to occur uninvited as a "slip of action."

The classic example of a capture error [is] the example from James of the person who went to his room to change for dinner and found himself in bed. Here are two more examples, one from my collection and one from Reason's:

I was using a copying machine, and I was counting the pages. I found myself counting "1, 2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King." (I have been playing cards recently.)

I meant to get my car out, but as I passed through the back porch on my way to the garage I stopped to put on my Wellington boots and gardening jacket as if to work in the garden. (Reason, 1979).

Rumelhart and Norman exclude these errors from their typing model: "There is no provision in the model for capture errors." And both earlier and later models of typing, as far as I can tell, either ignore these "capture errors" or similarly mention them without serious engagement, probably because they're much rarer than other sorts of typos.

But what I care about is something else. No doubt there are also "capture errors" in speech, though I don't think there's been an attempt to distinguish them systematically from other kinds of words substitutions. What's interesting — and apparently ignored by psycholinguists — is the striking difference that I noted in "Slips of the finger vs. slips of the tongue", 3/4/2018:

There's an interesting and understudied way that typing errors and speaking errors are different. From Gary Dell, "Speaking and Misspeaking", Ch. 7 in Introduction to Cognitive Science: Language, 1995:

One of the most striking facts about word slips, such as exchanges, anticipations, perseverations, and noncontextual substitutions, is that they obey a syntactic category rule. When one word erroneously replaces another, most of the time the target and substituting word are of the same syntactic category. Nouns slip with nouns, verbs with verbs, and so on.

In other words, we're NOT likely to say something like "When one word erroneously replacement another, …" or "exchanges, anticipation, perseverations, and noncontextual substituted […] obey a syntactic category rule".

But errors of this type are fairly common in typing. They seem to be cases where we've started to type the right thing, but as our attention shifts to the following material, our fingers follow a familiar but incorrect path.

I suspect that an explanation of this difference would tell us something important about speech production.

Some relevant past posts:

"A Cupertino of the mind", 5/22/2008
"What the fingers want", 7/30/2015
"Slips of the finger vs. slips of the tongue", 3/4/2018
"'Evil being protesting'", 6/27/2018

And in 2009, Stan Carey wrote about typing that for than ("A typo more mysterious that most"), and then catalogued many published examples ("Even stealthier than I thought", 5/5/2010).

What brought this all to mind was someone who commented on Nikola Jokić's role in Sunday's Denver/Minnesota NBA playoff game by writing:

He player 47 minutes tonight. He should have played like 41.

Again, this is a normal type of "capture error" in typing, but it would never happen in speech.

If I've missed some relevant research — which is likely — please let me know in the comments.




  1. Jerry Packard said,

    May 20, 2024 @ 7:55 am

    How about something like this. In writing production, the motor output system is a misselected complete motor routine output, whereas in speech the incorrect output involves the misselection of items to appear in the preformed syntactic frame. Borrowing from the speech production models of Levelt or Garrett, the semantic ‘message generating’ procedure is followed by the generation of a grammatical frame, followed by insertion of lexemes into the frame slots. The selection error in the case of speech output is a misselection of items for insertion into a preselected syntactic slot, whereas in the typing error case the misselection is of a complete but incorrect word, misselected by choosing a word with a similar beginning sequence, because that’s how those words are indexed. Crazy, no?

  2. Mark Liberman said,

    May 20, 2024 @ 8:12 am

    @Jerry Packard:

    That makes sense, and is similar to the model proposed in Thomas Berg, "Slips of the typewriter key", 2002 — though Berg doesn't engage the topic of POS-changing "capture errors"…

  3. Benjamin E. Orsatti said,

    May 20, 2024 @ 8:42 am


    So, the "misselected complete motor routine output" is when, on my way to writing COOPERATING, I get "caught" by some mnemonic association and end up "firing" to my motor neurons the discrete output COOPERATION?

    …but because speech acts involve a "selection of items to appear in the preformed syntactic frame", "they obey a syntactic category rule", which is why I'd never _speak_ COOPERATION instead of COOPERATING (though I might speak COAGULATING?)?

    I wonder what the implications are for oral versus written communication in terms of how information is exchanged and if people, by and large, are sufficiently attuned to those implications.

  4. Jerry Packard said,

    May 20, 2024 @ 10:51 am

    I’m not sure what the implications are for oral versus written communication, but one interesting thing about the speech error substitutions is that they usually, as Gary Dell has shown, switch lexemes while keeping their grammatical inflections (-s, -ed, -ing) in their original positions. This is the sort of evidence that shows us that syntactic frame is constructed before lexical retrieval in speech production (unless you are a lexicaist who believes that lexical items are strongly endowed with syntactic POS etc. information, which is a whole nother topic).

  5. Garrett Wollman said,

    May 20, 2024 @ 11:51 am

    I've lived and worked in the same place for 23 years. My commute (thankfully no longer daily) involves driving on the Massachusetts Turnpike from my home city into Boston, and I have on occasion followed the procedure for driving to work when intending to drive somewhere else, and thereby failing to get off at the right exit, requiring an extra dollar in tolls and several miles more driving. It never occurred to me, however, that this might be linked in some way to my inability to type "Cape Code", erm, "Cape Cod", correctly.

  6. David Marjanović said,

    May 20, 2024 @ 11:52 am

    Yes, I do that a lot.

    This, though:

    He player 47 minutes tonight. He should have played like 41.

    …could be a genuine typo. D and R are neighbors on QWERT keyboards.

  7. Mark Liberman said,

    May 20, 2024 @ 12:32 pm

    @David Marjanović: "D and R are neighbors on QWERT keyboards."

    Yes, but they're typed with different fingers. Though thumbing on a phone screen, you might be right.

  8. Philip Taylor said,

    May 20, 2024 @ 12:40 pm

    "Yes, but they're ["D" & "R"] typed with different fingers" — well, yes, by conscientious touch typists, but although I was taught touch-typing at the age of 16, my fingers no longer rest on the home keys and I tend to use whichever finger is most convenient for the stretch of prose under construction. So here, for example, and re-typing the above to watch my own fingers, I see that I typed both the "D" and the "R" of ["D" & "R"] using my left forefinger. But were I to type "the quick brown fox jumps right over the lazy dog's back", I would use my forefinger for the "r" and my left middle finger for the "d".

  9. Kenny Easwaran said,

    May 20, 2024 @ 4:32 pm

    I've often found myself adding D at the end of a word that ends with OUL, so that SOUL becomes SOULD. I think OULD is such a common word ending (WOULD, SHOULD, COULD) that, like driving home rather than to the store, the habit kicks in.

  10. Vassili said,

    May 20, 2024 @ 11:59 pm

    and then there is SMBC:

  11. Frans said,

    May 21, 2024 @ 2:45 am

    I always find it surprising that so few people seem to bring up writing by hand in this context. But it looks like I did, so I can simply refer to what I typed back in 2018:

  12. Cervantes said,

    May 21, 2024 @ 8:51 am

    Although I know the difference perfectly well, I will sometimes type they're for their. Of course in speech, substituting homophones is impossible, doesn't even make sense as a concept.

  13. David Marjanović said,

    May 21, 2024 @ 5:04 pm

    What Frans said about handwriting.

    Yes, but they're typed with different fingers.

    That doesn't mean the fingers never slip! I touch-type and have made typos of this rare sort.

  14. Bob Ladd said,

    May 24, 2024 @ 12:54 pm

    I don't have many occasions to type the word "glad", but when I do, it all too often comes out "gladd".

  15. Chas Belov said,

    May 26, 2024 @ 1:13 am

    I've had a long-time habit of mis-writing the last letter of a word. I can understand mixing d and t since they're voiced and unvoiced versions of the same sound, but sometimes they're unrelated.

  16. Chas Belov said,

    May 26, 2024 @ 1:14 am

    Also sometimes happens when typing.

    But it's particularly annoying when doing crosswords.

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