In our daily life, those products which are misapplied frequently are always because they does not provide a proper clue for users. If they did, however, another question is whether human beings could perceive it intuitively. There still exists a fuzzy zone to explain the difference between the real affordance and the perceived affordance. The purpose of this study is to discuss how human beings perceive the characteristic of physical sizes. This study uses mug as an example to show that the handle scale and size would affect the way human beings reach out fingers to grip a mug. We found that when people trying grip a mug unconsciously or directly, the length of the handle is the most important factor that would affect their real affordances and behaviors.