Barrier scanning is a term given to the type of scan behavior that deviates from the ideal user flow due to those on site design elements that can impede, redirect, or coach a certain type of user engagement. This is important, because this is this type of behavior that is working in combination with the value of your content, benefit messaging, and relevance to cause your websites to have high abandonment rates, low conversion rates, and lower ROI.

Understanding barrier scanning can greatly improve your website’s ability to resonate with your market by helping to make navigation and conversion paths more in-line with an intuitive user response, by making your page more dynamic, and by giving your content a better chance to sell to your unique visitor.

Source: http://www.enquiroresearch.com/barriers-on-a-website.aspx