A method for recording verbal behavior in free-play settings.

The team filmed preschoolers during free play. They wanted a cheap way to track speech that anyone could use.

Two new observers watched the tapes. They paused, rewound, and wrote down every word and sound.

Kids moved a lot. Some hopped, some flapped. The test was to see if the tape method still held up.

Both observers agreed on almost every code. Even with wild movement, the speech data stayed clean.

The simple setup worked for both typical kids and kids with delays. No pricey gear was needed.

Machado et al. (2021) now lets you score at 5× speed after a quick computer class. Their tool keeps the same accuracy but saves two-thirds of your evening.

Machado et al. (2019) showed 3.5× speed works too. Both newer papers keep the 1971 idea—tape gives reliable data—then add fast-forward and training to save time.

Greenlee et al. (2024) go further. They let the computer count movement for you. The old tape method becomes fully automatic, no human pause button needed.

You still need rock-solid data before you teach or graph. This 1971 paper proves videotape can give that solid base even when kids bounce off the walls. Use it as your reason to hit record, then borrow the newer speed and auto-tracking tricks to finish faster.