Performance Errors
Exploring the Hidden Architecture of Slips, Slips, and Schemata
Slips are errors we make in spite of knowing better. They differ from mistakes born of ignorance. For example, if we commit a spoonerism—such as the Reverend Spooner’s famous slip “our queer old dean” instead of “our dear old queen”—the error is not due to ignorance. The correct information is available, but it fails to influence the act of speaking in time to make a difference.
Thus, slips of speech and action inherently involve a dissociation between what we do and what we know. This is one reason to believe that slips always involve separable, specialized processors. Slips of speech and action generally decompose along natural fault lines. Errors in speech almost always involve units like phonemes, words, stress patterns, or syntactic constituents—the standard building blocks of language. We do not splutter randomly when making these errors. This is another reason to think that actions are composed of analogous units, which sometimes fall apart along their natural lines of cleavage.
Action errors suggest the same kind of modular organization. For instance, many spontaneous action errors collected by Reason (1984) involve the insertion, deletion, or exchange of coherent subunits of an action. Consider these examples:
Deletion error:
“I went into my room intending to fetch a book. I took off my rings, looked in the mirror, and came out again—without the book.”Insertion error:
“As I approached the turnstile on my way out of the library, I pulled money out of my wallet as if to pay—although no money was required.”Insertion error:
“During a morning in which there had been several knocks at my office door, the phone rang. I picked up the receiver and bellowed ‘Come in!’”Component exchange (“behavioral spoonerism”):
“Instead of opening a tin of Kit-E-Kat, I opened and offered my cat a tin of rice pudding.”Component exchange:
“In a hurried effort to finish the housework and have a bath, I put the plants meant for the lounge in the bedroom, and my underwear in the window of the lounge.”
In all five examples, action components are inserted, deleted, or exchanged in a smooth, seemingly volitional fashion. This suggests that normal action is organized in modular subunits. Reason (1984) calls these modules “action schemata,” which “can be independently activated, and behave in an energetic and highly competitive fashion to try to grab a piece of the action.” In other words, action schemata compete for the privilege of participating in an action—sometimes entering the wrong context, as in examples 2–5 above.
This claim aligns with the widespread view that detailed action control is decentralized or “distributed,” so that much of the control problem is handled by local processes. It also accords with findings on the autonomy of highly practiced skills that have become automatized and largely unconscious. Normal actions, of course, combine many such practiced skills into a single, purposeful whole.