8. People Can Miss Changes in Their Visual Fields

The Monkey Business Illusion (Embed)

Watch This Video:

Caption: : https://www.youtube.com/watch?v=IGQmdoK_ZfY

Did You See the Gorilla?

This video is an example of change blindness or inattention blindness.  People commonly miss big changes in their visual fields.  Eye-Tracking - A technology that lets you view and record what a person is looking at, what order they see it, and how long they look.  When eye-tracking is used on the "Gorilla Video", everyone sees the gorilla, but only about 50% of people are aware of it. 

Conclusion

Don't assume people will see things on your web page just because it is there.  If you want to be certain that someone sees something on your web page add something like a visual or auditory cue.  Eye-tracking data is helpful but not always completely correct - use with caution.