There are many home page focal points that put their call to action buttons in the bottom left area. This is the weak fallow area that users pay the least attention to. Users may sweep their eyes across your call to action button, but they won’t fixate on it for long. When the user finishes viewing and ends at the terminal area, they have to move their eyes back to the weak fallow area to click the call to action button. This not only forces users to move their eyes more, but going back to the weak fallow area is an unnatural movement that goes against their viewing rhythm. Call to actions belong in the terminal area because they’re the last thing users need to see to take action.
The example below arranges the home page focal point elements perfectly. The headline, which users read first, is in the primary optical area where users first look. The supporting text, which users read after the headline, is in the strong fallow area, where users move their eyes to second. The product image, which users look at after they read, is in the weak fallow area. This is the best spot for the product image because images tend to get longer visual fixations. Placing it in the weak fallow area means that the image won’t get fixated on too long over other elements. Each element is efficiently placed so that it follows the user’s natural viewing pattern. A call to action in the terminal area makes it quick and easy for users to take action.
The difference between a left and right call to action may only seem like its placement. But when you look deeper, where you place your call to actions can affect whether users click them or not. Knowing this will allow you to promote and display your product in an efficient way that makes users act.
source: http://uxmovement.com/buttons/why-users-click-right-call-to-actions-more-than-left
