About Vocady — why it exists and what it is built on

Vocady is a vocabulary app for iOS and Android. You write a word by hand during class, and the app takes it from there: it reads what you wrote, fills in the rest of the entry, and brings the word back to you days later as a question you have to answer from memory.

The word you were sure you had written down

Anyone who has studied a language has a version of this story. A word comes up, it matters, you write it in the margin before the teacher moves on. Weeks later you need it and it is gone.

Sometimes it is gone from the page too. You find the right notebook and the right afternoon and there is half a word in handwriting you were in too much of a hurry to make legible, with nothing next to it: no meaning, no sentence, no clue why you thought it was worth the ink. You wrote it down. That was supposed to be enough.

The notebook was never the problem. The problem is that a word written once and never looked at again is, for all practical purposes, a word you did not write down. Everything that would actually fix it (looking the word up properly, copying out a sentence, coming back to it on Thursday) is work you have to do after class, in the evening, when the reason you cared has faded.

Vocady is the smallest fix I could think of. Keep writing by hand, because you are doing that anyway. Let the app handle everything that happens after the pen leaves the page.

What the app does

You write the word. Your phone reads it right there, without sending it anywhere. It reads more than 300 languages, usually before you have finished setting the pen down. Once your language is loaded, it works with no signal at all: basement classrooms, planes, the subway.

Then the entry fills itself in. By the time you glance back, the pronunciation, the meaning, the part of speech, a short grammar note and two example sentences with translations are already there. Japanese and Chinese words arrive with the readings printed above the characters. You type nothing.

If the words are already on a page (a textbook, a whiteboard, a handout someone photocopied badly), one photo takes up to 50 of them at once.

Your handwriting stays handwriting. Tap a word later and it redraws itself the way you wrote it, in the same order and at the same pace, hesitation before the last letter and all. It is not the most useful feature in the app. It is the one people show other people.

The word you wrote on your phone is on your tablet when you open it. You do not press anything to make that happen.

The part that does the work

Daily Recap asks you at most ten questions a day. One word becomes one question, and no word is asked twice in the same sitting. All five kinds of question make you produce the answer instead of recognising it: choose the meaning, fill the blank, go from a meaning back to the word, assemble a sentence, write the word out by hand.

When the app cannot find convincing wrong answers to stand beside the right one, the question does not get skipped; it gets harder. Four choices become three, then two, then no choices at all, and you write it out yourself.

Which word comes up, and when, is not something you manage. Words you have never studied go first, then the ones you keep getting wrong, then the ones you have not seen in a while. There is no deck to maintain and no schedule to keep, only the ten questions.

The app itself is available in nine languages.

Why the research is here

Everything above is a claim about how memory works, whether I phrase it that way or not. Deciding that reviewing matters more than collecting, that a question beats rereading, that handwriting earns its place — those are not design preferences, they are bets on findings that could turn out to be wrong.

So here are the studies I leaned on, with their numbers, including the ones it would be more convenient to leave out. If you want to check whether I read them correctly, you should be able to.

Kobayashi (2005)

Source and statistics

A meta-analysis of 57 studies and 131 independent samples. Taking notes versus not taking notes gave a weighted mean of d = 0.22. The act of writing something down, on its own, is a small effect.

Kobayashi (2005), Contemporary Educational Psychology, 30, 242–262

Norouzian, Jin & Webb (2025)

Source and statistics

A reanalysis of 27 studies and 55 effect sizes. Conventional note-taking came out at 0.275 (p = 0.299, not significant), while keeping a vocabulary notebook came out at 1.852 (p = 0.003), the largest value in the set.

Norouzian, Jin & Webb (2025), The Modern Language Journal, 109(1), 171–193

Flanigan et al. (2024)

Source and statistics

Across 49 effect sizes, notes that were reviewed gave g = 0.421 and notes that were not gave g = 0.208, Q(2) = 7.94, p = .019.

Flanigan et al. (2024), Educational Psychology Review, 36:78

Dunlosky et al. (2013)

Source and statistics

Of ten study techniques, only two were rated high utility: practice testing and distributed practice. Rereading was rated low.

Dunlosky et al. (2013), Psychological Science in the Public Interest, 14(1), 4–58

Rowland (2014)

Source and statistics

Across 159 effect sizes, testing with feedback gave g = 0.73 and testing without feedback gave g = 0.39.

Rowland (2014), Psychological Bulletin, 140(6), 1432–1463

Cepeda et al. (2006)

Source and statistics

Across 317 experiments with 14,811 participants, spaced practice recalled 47.3% against 36.7% for massed practice.

Cepeda et al. (2006), Psychological Bulletin, 132(3), 354–380

Each figure stays next to the study that produced it. Nothing on this site adds or multiplies effect sizes from different studies into a single claim about how much better you are going to do.

What handwriting is, and is not, evidence for

An app built around handwriting would love to be able to say that handwriting beats typing. The meta-analyses do not say that, so I am not going to either.

Source and statistics

Voyer et al. (2022) report g = −0.008, and Urry et al. (2021) report g = 0.04, which passed a test of equivalence to zero.

Voyer et al. (2022) · Urry et al. (2021)

Wiley and Rapp taught 42 adults the shapes of letters from an alphabet they had never seen before. Writing the letters beat typing them, and both beat looking at them; on spelling words that had never been trained, writing beat typing again.

Source and statistics

Letter writing scores of 91.0 for writing, 78.5 for typing and 64.5 for the visual condition. On untrained word spelling, 76.3 for writing against 62.3 for typing.

Wiley & Rapp (2021), Psychological Science, 32(7), 1086–1103

What that study measured is the acquisition of letter forms, not the understanding of a lecture, and not vocabulary retention in general.

So handwriting is in this app for two reasons, and only two. It is what you are already doing in the margin of a notebook, so capturing a word costs you nothing extra. And when the script itself is new to you (the first hundred characters, the first week of an unfamiliar alphabet), there is evidence that forming the shape by hand helps.

Who makes it

Vocady is built by Yeonseok Kim, an independent developer. There is no research group behind it, and none of the studies cited on this site were conducted by me.

What I did do is read them, check every number against the original paper or the publisher’s abstract, and drop any figure I could not trace to a published source. Where a study cuts against what the app does, it stays on the page and is stated plainly. An app that hides the inconvenient half of the evidence is asking you to trust it about the rest.

If a number here misreads its source, please write to dev.tastekim@gmail.com and I will correct it.