The Gravity of the Center: What Grabs Attention in Vertical Videos?

Vertical videos are everywhere - TikTok, Instagram Reels, YouTube Shorts - and they’ve completely changed how we watch and create content. But here’s the question: where should you place your subject in a vertical frame to make your audience pay attention?

A team of researchers led by Afzaal Yousaf Baig (2025), used RealEye webcam-based eye-tracking to find out. Their goal: to understand how the position of a subject (or “Area of Interest,” AOI) affects attention and engagement.

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How RealEye Was Used

The researchers designed a within-subject experiment - meaning every participant watched both test videos - using RealEye to track where people looked.

• 40 participants, aged 18–35
• Two 20-second vertical videos were created:
  1. Central AOI video: The main subject always stayed in the middle of the screen.
  2. Dynamic AOI video: The subject kept moving around - top, bottom, left, right.

Participants watched both videos on their own smartphones, through the RealEye platform. RealEye used each device’s front camera to measure where and how long their eyes fixated, and how often their gaze jumped between points (called saccades).

From this, the team calculated:

• Fixation Duration – how long viewers looked at something
• Saccade Count – how often their eyes moved
• Coefficient K – a measure showing how “efficient” or focused the attention was (longer fixations and shorter saccades = focal attention).

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What They Found

The results were clear: centered subjects win.

• The Central AOI video led to longer fixations and fewer saccades, meaning viewers were more focused and didn’t need to “search” for the subject.
• The Dynamic AOI video made viewers’ eyes move around more, increasing cognitive load (mental effort).

In simple terms: When the subject was always in the middle, people watched more comfortably, stayed engaged, and processed the content better.

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Why This Matters for Creators and Marketers

This study shows that in the fast-paced world of vertical video, simplicity and centrality are powerful.

• Placing the main subject in the center makes it easier for viewers to focus.
• It reduces “visual searching,” keeping attention steady.
• It helps audiences process messages more effectively - which is key for marketers, UX designers, and educators.

“The gravity of the center” helps reduce mental effort and keeps viewers engaged longer.

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You can run a similar study!

Follow the steps below to start your own experiment with RealEye:

1. Go to RealEye Dashboard and create or log in to your account.
2. Purchase the License of your choice (https://www.realeye.io/pricing). If you need any custom adjustments, contact us at contact@realeye.io. We are happy to help!
3. Activate your license by following the instructions in the RealEye License Activation Guide

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‍Ready to set up your own study? Visit RealEye Support page to learn more and keep us posted on your results! 🚀