IME state is a hidden mode
Aliases: Chinese-English mode · IME mode · composition mode
What it is
With an IME on, the same Latin letters are not those letters; they are a code still in composition. That state is rarely announced by a prominent surface that says “keys you type now will become character candidates,” so it is a hidden mode: people type the English they think they are typing, the machine collects a code, and the wrong gear is exposed only when a candidate window or a run of characters appears.
Why it happens
The mode lives in the machine: Chinese / English, full-width / half-width, and “composing / already committed.” The indicator is often a tiny menu-bar glyph or a near-invisible mark by the caret, unread while gaze sits between text and keyboard. Composition accumulates keystrokes into a code buffer and does not emit a final character; English should commit per key. Two semantics share the same physical keys. The typical mode error is not a missed key. It is a stretch of characters the user never picked, or a stretch of pinyin that should have been composed and was left raw. Because the buffer can be long, discovery comes several words later and deletion has to unwind a block. A quasi-mode (holding a modifier) has a bodily cue; IME gear persists after release, a true mode, without the persistent visibility a true mode needs.
Studying it
In mixed Chinese–English tasks, shift attention (look at source material, come back and type) and log strings produced in the wrong gear, time to notice, and the action that clears the composition buffer. Independent variables include indicator size and placement, whether the composition buffer is highlighted, and how often the task switches script; dependent measures include mode-error count, mean notice delay, and characters wrongly committed. Testing “can they switch IMEs” misses hiddenness: errors happen while people believe they are already in the right gear.
Where it stops holding
People who type one script and never turn the IME off almost never hit this error. A hardware lamp or a language light on the keyboard makes the mode quasi-visible and errors drop. Password fields that force English and disable composition remove the mode by field semantics rather than displaying it better. Caps Lock is a different true mode; do not draw it as the same indicator as IME gear.
Applying it
- Paint the composition buffer in the text with a style clearly different from committed text, so “now encoding” does not depend on finding a system icon.
- Beside mixed-script fields, provide a current-language mark larger than the system default, or a reversible hint on the first keystroke in the wrong gear.
- In mixed copy-typing, count wrongly committed characters; if people find them only by rereading a paragraph, the indicator is still hidden.