Scent Trail of View Cart, Add to Cart and Proceed to Checkout Buttons

Have you ever wanted to be able to have a collection of "view cart" or "add to cart" buttons and compare them to other buttons, such as "proceed to checkout" buttons? While designing a new website or a new web page for a multivariate test, proper homework has to be done regarding a nice collection of buttons which are primarily used during the checkout process of e-commerce websites.

Intriguing is not the design of the buttons it self, but the relationship between the buttons on each website. Does the view cart has a strong presence on the pages or it's obscured by other designs elements and distractions? Or, does add to cart attracts more clicks than a Buy Now button?

Is there any scent trail among these three buttons? Is it the same term used on the view shopping cart button and on add to cart button? (i.e. the word Cart used on both View Cart and Add to Cart buttons).

There is a scent. The word used on the "View" button is used again on the "Add" button on 92 out of more than 100 websites we've looked at. On the other hand there is no obvious color consistency for the "Add" and "Checkout" button. 58/102 will not keep the same color for the aforementioned buttons, while the rest, 46 will do. This behavior was expected, for several reasons: different emphasis on different elements, business rules and look and feel issues.