Why reading fast and focused actually works

Why normal reading is slower than it has to be

When you read a normal line of text, your eyes don’t move smoothly across it. They make a series of quick jumps called saccades, pausing briefly on certain words before jumping to the next point. Some of that movement is your eyes searching for the most useful part of the next word, often not its exact center, but a point slightly left of it. That search is also why it’s so easy to lose your place and reread the same line.

RSVP removes the search. Instead of scanning a line, words are presented one at a time in a fixed location, timed automatically. Your eyes stay still. Only the word changes.

What the focus letter adds

The optimal recognition point is the letter in a word where your eyes naturally tend to land first, usually just left of the midpoint, shifting slightly with word length. Centering each word on that letter, instead of on the word as a whole, puts your eyes right where they’d naturally want to be, without having to find it themselves. That’s why Codolo highlights it in red.

“Optimal recognition point” is the name a commercial speed-reading product (Spritz) gave this idea. The underlying effect itself isn’t Spritz’s invention: researchers have studied it since the 1980s under the name optimal viewing position, independent of any app, see the sources below.

Why Codolo also plays the audio

Codolo’s name comes from "cognitive download": getting text into your head as efficiently as possible. Reading silently in your head, called subvocalizing, is often described as capping your natural reading pace at roughly how fast you can talk. Pairing the visual focus display with narration you listen to at the same time sends the same words through two channels, sight and sound, instead of just one.

There is research behind this. Your working memory takes in what you see and what you hear through separate channels rather than one shared bottleneck. In a series of experiments, people who read along with a spoken explanation understood and remembered more of it than people who only listened. Research on reading printed text while it’s read aloud points the same way: a systematic review found a real, if modest, comprehension benefit over reading alone, and it held up reliably only when the pace was set for the reader. That’s exactly how Codolo works: narration sets the pace, the display follows it.

Not every study finds a difference compared with reading on your own, so think of it as a boost to focus and understanding, not a memory trick.

What this can and can’t do for you

This approach is a genuine, studied way to increase reading speed, and many people find it noticeably faster once they adjust to it. It works by removing the eye-movement overhead of normal reading, not by making your brain process language faster than usual.

That’s also the trade-off, and it’s well documented, including in a comprehensive review of decades of reading research commissioned specifically to answer whether speed-reading apps deliver on their claims: there’s a real speed/comprehension trade-off, and no eye-movement trick lets you process language faster than your brain normally can. A dedicated study of Spritz’s own RSVP format found the same thing, comprehension measurably drops as speed increases, especially past what’s comfortable for the material. Codolo lets you set your own pace for exactly this reason: faster for easy, familiar text, slower for anything you need to absorb carefully.