| Candidate answer | Label | Diagnosis by Claude Opus 5 |
| The sleeves of the new walking-dress are made moderately close at the shoulder, widening toward the elbow, and finished at the wrist with a narrow frill of lace, which gives a light and graceful effect. | (a) | Language model. The tell isn’t any single anachronism; it’s the absence of nouns a real fashion writer couldn’t have avoided. Three clauses about a sleeve and not one fabric, not one trade name, not one named sleeve shape. Period copy names things—coat sleeve, demi-long, bishop, pagoda—because the reader is being told what to ask for. This sentence instead describes the silhouette from scratch, which is what you do when you don’t have the vocabulary and are working from a mental image. And the shape it describes is incoherent: narrow at the shoulder, widening toward the elbow, then somehow a wrist frill—that’s a pagoda sleeve grafted onto a cuffed one, i.e., the average of two decades rather than either. The closer, “which gives a light and graceful effect,” is the giveaway you’d expect: an evaluative summary clause with no referent, appended because the model has learned that period prose sounds appreciative. Real columns do say the effect is graceful, but they say it about a named thing. |
| His shirt, which looked as if it never could have been whole and white, had more than half the sleeves torn away, and fell open in front for want of a collar, to say nothing of a button and buttonhole. | (b) | I’m keeping, though it’s the one I’d argue about. It’s fiction, not fashion copy, so the genre heterogeneity is jarring—but ladies’ magazines of the 1870s were mostly fiction by page count, and reprinting English serial matter was standard. It has the Dickensian comic apposition (“to say nothing of a button and buttonhole”), so if it’s an impostor it’s an 1850s–60s British novel rather than a model output. What holds me is “looked as if it never could have been whole and white”—the counterfactual pushed back past the garment’s own history is a strange enough construction that I don’t think it’s synthetic. Models write “looked as though it had never been white.” That extra modal is a human doing something odd on purpose. |
| Dress of blue pique, made with a plain gored skirt, scalloped on the bottom, and trimmed with white linen braid and pearl buttons, and a plain square-necked waist without sleeves, worn over a guimpe of white nainsook, finished at the neck and wrists with Valenciennes lace. | (c) | Is the anchor. Pique, gored skirt, linen braid, guimpe over a sleeveless square-necked bodice, nainsook, Valenciennes—this is a misses’ or child’s summer dress plate, mid-1870s, and American. “Waist” for bodice is the decisive nationality marker; a British book would say bodice or corsage. The description is also usefully boring: it enumerates and stops, with no aesthetic verdict at the end. |
| Pelisse of cotton-blossom-yellow gros de Naples, trimmed round the border, and on each side of the front, with vandykes in satin, and fastened down with mother-of-pearl buttons: plain sleeves, moderately full, and a pelerine cape, with an antique collar of pointed lace falling over. | (d) | Real, but roughly 1825–1835, and British. Four independent markers, all pointing the same way: pelisse as a current outer-garment name, gros de Naples as a current silk, vandykes as a trimming, pelerine with an antique collar. By the 1870s the pelisse is a costume-history word, gros de Naples has been displaced by gros grain and faille, and the vandyke/pelerine combination is grandmother’s wardrobe. “Cotton-blossom-yellow” belongs to the Ackermann’s / La Belle Assemblée register of invented poetic colorways. The syntax is right—the verbless nominal opening, the colon splicing the second half—which is exactly why it’s a good distractor: it fails on lexical dating, not on style. |