Why is an inverted car identified much better than an inverted face?

The present study shows that the presentation of a pair of the same car in upright and then in inverted orientation (UI-car) or in inverted and upright orientations (IU-car) increases recognition of an inverted car more than recognition of an inverted face given the previous presentation of a UI-face or IU-face. Presentation of a UI-face or IU-face exerts no significant effect on recognition of an inverted face and upright face. The differences between the visual forms of a face and a car and reasons why it is more difficult to unify a UI-face (IU-face) than a UI-car (IU-car) are discussed.