The face-inversion effect can be explained by the capacity limitations of an orientation normalization mechanism

The effect of orientation on face recognition was explored by selectively altering facial components (eyes and mouth) or by changing configural information (distances between components). Regardless of the type of change, a linear increase in reaction time for same‐different judgments was revealed when the faces were rotated away from upright. The analyses of error scores indicated that the detection of altered components was only slightly affected by orientation, while orientation had a detrimental effect on the detection of configural changes. These results are consistent with the assumption that rotated faces overtax an orientation normalization mechanism so that they have to be processed by mentally rotating parts, which makes it difficult to recover configural information