Looking at upside-down faces.
Yin, Robert K.
Journal of Experimental Psychology, Vol 81(1), Jul 1969, 141-145.
Compared memory for faces with memory for other classes of familar and complex objects which, like faces, are also customarily seen only in 1 orientation (mono-oriented). Performance of 4 students was tested when the inspection and test series were presented in the same orientation, either both upright or both inverted, or when the 2 series were presented in opposite orientations. The results show that while all mono-oriented objects tend to be more difficult to remember when upside-down, faces are disproportionately affected. These findings suggest that the difficulty in looking at upside-down faces involves 2 factors: a general factor of familiarity with mono-oriented objects, and a special factor related only to faces. (PsycINFO Database Record (c) 2012 APA, all rights reserved)