The Science Behind Bionic Reading: How Bolding a Few Letters Helps You Read Faster

How Your Eyes Actually Read

Reading feels smooth, but it isn't. Your eyes move through text in a series of rapid jumps called saccades. Between each jump, they briefly pause on a cluster of letters for roughly 200 to 250 milliseconds. Those pauses are called fixation points, and they're where the real reading happens. During a saccade, your vision is essentially suppressed. You only take in information while your eyes are still.

Most readers make about four to five fixations per second. Each fixation captures a "window" of roughly 7 to 9 letters to the right of where you're looking and about 3 to 4 letters to the left. If a word is short enough, one fixation is all you need. Longer words often require two.

Here's the key insight: your brain doesn't need to see every letter in a word to recognise it. Research going back to the 1970s shows that readers use the first few letters of a word, combined with context, to predict the rest. Your mind fills in the gap. This is why you can read text with scrambled middle letters almost as quickly as normal text.

What Bionic Reading Does

Bionic Reading takes that natural shortcut and makes it deliberate. It bolds the first portion of each word, typically the first two to four letters, creating what its developers call artificial fixation points. These bold fragments act as visual anchors that pull your eyes forward through the text at a steady rhythm.

Instead of your eyes having to "discover" where to land on each word, the bold portion signals the right spot immediately. Your brain grabs that anchor, recognises the word, and your eyes jump to the next one. The result is fewer wasted saccades, less backtracking, and a noticeably smoother reading experience.

Notice how the bold fragments create a visual "track" through the sentence? Your eyes are naturally drawn to those anchor points, and your brain fills in the rest. Most people report that the bionic version feels faster to read, even on a first attempt.

Adjustable Intensity: Finding Your Sweet Spot

Not every reader benefits from the same amount of bolding. That's why Type Shifter lets you adjust Bionic Reading intensity from 5% all the way to 45%. The percentage controls how much of each word gets bolded.

Low intensity (5% to 15%)

Only the first one or two letters of each word are bolded. This is subtle and works well for experienced readers who want a gentle nudge without the text looking dramatically different. It's also a good starting point if you've never tried Bionic Reading before and want to ease into it.

Medium intensity (20% to 30%)

This is the sweet spot for most people. Two to four letters per word are bolded, which gives your eyes clear anchor points without making the text feel heavy. If you're not sure where to start, try 25% and read a couple of paragraphs. Most users settle somewhere in this range.

High intensity (35% to 45%)

A larger portion of each word is highlighted. This is particularly helpful when you're reading unfamiliar or technical material, working through a dense textbook, or when you need maximum focus. Some readers with ADHD find higher intensities more effective because the visual anchors are stronger and harder to skip past.

Who Benefits the Most?

Bionic Reading isn't only for speed readers. It helps a wide range of people for different reasons.

• People with ADHD: The bold fixation points give your eyes something to lock onto, which reduces the tendency for your gaze to drift off mid-paragraph. Several ADHD communities online have reported that Bionic Reading helps them stay on track through longer passages.
• Readers with dyslexia: When combined with the OpenDyslexic font (available in Type Shifter), Bionic Reading provides two layers of support: the font reduces letter confusion, and the bold anchors reduce tracking errors. The Dyslexia Friendly template in Type Shifter turns both on at once.
• Students and researchers: If you regularly work through textbooks, journal articles, or lengthy reports, Bionic Reading can cut your reading time by roughly 20% to 25% without hurting comprehension.
• Non-native English speakers: The bold anchors help with word recognition when you're reading in a second language, because they give your brain a stronger initial cue to work from.
• Anyone who reads a lot: Even if you don't have a specific need, less cognitive effort per word adds up over a long reading session. You'll feel less fatigued at the end of a long document.

Try It Yourself

The best way to understand Bionic Reading is to experience it with your own text. Open Type Shifter, paste in something you're currently reading, set the intensity to 25%, and hit "SHIFT MY TEXT." You'll feel the difference within a few sentences.

You can adjust the intensity, switch templates, toggle dark mode, and export the result as PDF, DOCX, EPUB, or HTML. Everything processes locally on your device, so your text never leaves your computer.

Type Shifter offers a 14-day free trial with full access to every feature, including Bionic Reading at all intensity levels, all 26 templates, 113+ fonts, and all export formats. No credit card required. No restrictions.