The Horse Raced Past the Barn Fell. Read It Again, It Is Grammatical
By the BrainSnail editorial team. How these articles are written and checked, and how to tell us when one is wrong.
Some sentences lead a reader confidently down one interpretation and then reveal it was wrong, which exposes how understanding actually proceeds while reading.
What happens to the reader
A reader builds an interpretation continuously while reading rather than waiting for the end of a sentence. Certain sentences are constructed so that the most natural interpretation of the opening turns out to be impossible once the final words arrive, forcing a complete reanalysis. The experience is distinctive, a sudden sense that the sentence is broken, followed by the discovery that it is perfectly grammatical and that the mistake was the reader's. Measurements of eye movements show the reader stopping and going back to the point where the wrong choice was made.
The classic examples
A handful of sentences are used in the research repeatedly:
- •The horse raced past the barn fell
- •The old man the boats
- •The complex houses married and single soldiers
- •The cotton clothing is made of grows in Mississippi
- •Each hinges on a word that can be two parts of speech
- •The reader commits to the commoner reading and has to undo it
What it shows about reading
The phenomenon is evidence for a particular account of how sentences are understood, and that is why psycholinguists care about it. If a reader waited for a complete sentence before interpreting, the effect could not exist, since the ambiguity resolves itself by the end. The disruption proves that structure is assigned word by word as the words arrive. It further shows that only one structure is pursued at a time rather than several in parallel, since pursuing both would make the ending unproblematic. Which structure gets chosen appears to depend on frequency, simplicity and the plausibility of the meaning.
Why some are worse than others
The severity of the effect varies enormously and the pattern tells you which cues readers rely on. A sentence is hardest when the misleading reading is far commoner than the correct one, so the reader commits strongly. It is easier when the meaning of the misleading reading is implausible, because plausibility pulls against the structural preference. Punctuation removes the effect almost entirely, which is why a comma in the right place rescues a difficult sentence. And spoken language is far less affected, because intonation and phrasing supply exactly the grouping that punctuation supplies in writing.
Why it matters outside the laboratory
The effect is not merely a curiosity and a writer who produces one accidentally has cost their reader real effort. Newspaper headlines generate them constantly because articles and auxiliary verbs are omitted to save space, which removes exactly the cues a reader uses to choose correctly, and collections of accidentally ambiguous headlines are a minor literary genre. Legal drafting avoids the constructions deliberately. Machine translation and speech systems face the same problem and solve it with statistics rather than with rules. Comedians exploit the effect on purpose, since a joke whose ending forces reinterpretation of its opening is a recognised structure.
The takeaway
Certain grammatical sentences lead a reader into an interpretation that the ending makes impossible, forcing reanalysis that eye tracking can measure directly. That they work at all shows structure is assigned word by word as reading proceeds, and that only one structure is pursued at a time. Headlines produce them accidentally by omitting the words that would disambiguate.