Comparison in Decision-Making

Dan Ariely also points out in his book, Predictably Irrational, that we tend to avoid difficult comparisons when making purchasing decisions, while gravitating toward easier comparisons. What does this mean? Suppose we are comparing products A and B, and these two products differ along many dimensions. Now suppose that we add a slightly inferior version of A to our set of choices. How does this affect our behavior? It turns out that adding a slightly inferior version of A to the mix enhances the likelihood to choose the better version of A. Why? Human beings tend to gravitate toward the "easy" comparison...i.e. comparing A to the inferior version of A. Once we do that, the choice becomes obvious.