The relationship between fractal dimension and other-race and inversion effects in recognising facial emotions

There is currently substantial literature to suggest that facial emotion recognition is impaired when other-race or inverted faces are presented. This study examined circumplex structures for recognising facial emotions under these conditions, directly measured those structures using a fractal dimension, and examined the difference between fractal dimensions. Results established that emotion ratings for the emotion prototypes used were sufficiently accurate under all conditions. Fractal analyses showed that the fractal dimensions of the circumplexes were significantly higher for recognition of facial emotions in other races than in one's own when the faces were presented upright; the fractal dimensions of the circumplexes were also higher for recognition of emotions in inverted faces than in upright faces in the own-race condition. The results suggest that a lower level of facial emotion recognition is associated with higher fractal dimension and that an increase of fractal dimension may be characterised by lack of facial familiarity.