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Scroll-Jacking

From the Neilson Normal Group blog:

Scrolljacking is a relatively recent design trend that involves changing the normal pace or direction of scrolling on a website. In our usability testing, we observed that websites with scrolljacking exhibit significant threats to user control and freedom, discoverability, attention, efficiency, and task success.

All very good things to note. Scrolljacking - changing the way scrolling works on your webpage - breaks a fundamental expectation of web-based interaction. It makes your site feel broken, especially on mobile.

But I wanted to add two things to this article.

1. It breaks spacebar navigation.
2. The scrolling inconsistency can make users motion-sick.

Spacebar Navigation

I’ll bd brief here because I think it is “less” of a problem (it is still a problem). Spacebar was the original way to scroll a page. Subsequently, breaking the scrolling concept into inconsistent chunks means spacebar no longer works for keyboard-based navigation. Users that do not or cannot use a mouse have additional trouble navigating scroll jacked pages.

In the case NN/g cited with the Apple Watch Ultra page, spacebar would skip content because space scrolled “too far” so text would fly by and vanish before I could read it.

Scrolljacking makes your page harder to read.

Motion-Sickness

This is a much bigger problem. Perception of motion when a user action is tied to an expectation of function not only feels broken in these cases but can through of user perception to cause motion sickness.

When the eyes perceive motion - like through flashing, animation, or scrolling - they tell your brain you’re moving. But your vestibular system - the internal level system in your ear - tells your brain you’re not moving. Plus, your proprioception - the way your body sense movement - also says you’re not moving.

The disconnect can result in lightheadedness, nausea, headache, and seizures in some cases.

It’s called “cyber sickness” and it is starting to gain a lot of research validity.

Here’s an example Google Scholar search It comes up a lot more in VR but can also appear in typical internet webpages any time those three sense are in conflict.

So… this seems like a really bad idea for designers. It’s, at best, disorienting and, at worst harmful to particular people.

And IDK about you but I don’t want to cause my readers harm.

References

Scrolljacking 101 - Neilson/Normal Group Apple Watch Ultra product page Quick overview at Healthline on cybersickness