Spell-check programs work best when they don’t have to think. Type typpo and any spell-checker will recognize that you probably meant typo. That’s what’s known as a “nonword” error—a spelling mistake that results in a combination of letters that doesn’t match any real word in the dictionary. Though many typos are of this sort, unfortunately these are the types of mistakes that humans are already adept at noticing. Both humans and spell-checkers struggle more with “word errors”—spelling mistakes that result in a real word but not the one that was intended. Homophones are one pitfall; proper names are another.
Far from making spelling obsolete, traditional spell-checkers often serve to reinforce its importance. A widely cited 2005 study found that students actually caught fewer spelling and grammar mistakes when their word processor’s language-checking program was turned on. The explanation: People placed undue confidence in the software, skipping over misspellings that the computer didn’t flag.
The same can happen with Web-based spell-checking, but it’s less common. That’s because search-based algorithms consider two things that spell-checkers don’t: context and human experience. Rather than checking a string of letters against a dictionary, Bing and Google check your phrase against the millions of other Web searches that people have conducted. The moment you type mor, a search engine will find the most popular search results that start with those three letters: mortgage calculator, morgan stanley, morgan freeman. It can work even if you start off on the wrong foot. Type tarmig and the first suggestion is ptarmigan, an oft-misspelled game bird. And while autocomplete isn’t perfect on homophones, it’s better than Word’s spell-checker. If you type here, it doesn’t know that you might have misspelled hear. If you type do you here what I here, however, it knows which Christmas carol you’re asking about.
Still, autocomplete is no substitute for human spelling skill, for several reasons. For one, you need to get somewhat close to a word’s proper spelling in order for it to be helpful. Second, it hasn’t yet been incorporated into most email and word-processing programs. The recent Google Docs upgrade is a significant improvement over traditional spell-check tools, but work remains to be done. Google Docs now flags the Brittany in “Brittany Griner Baylor” because that’s a popular search term. But when it comes to a phrase like “Brittany Griner of Baylor,” which you’d be more likely to use in an essay, Google Docs is mute. Spell-check programs will probably never make spelling as easy as a calculator makes arithmetic. But at least now they can put two and two together.