Faces from different dimensions: The role of distinctiveness in the flashed face distortion effect

The flashed face distortion effect (FFDE) is a phenomenon where ordinary faces begin to appear distorted and even grotesque. The effect is caused by the rapid flashing of eye-aligned faces, and is enhanced when these faces are presented peripherally, relative to a central fixation point. The FFDE seems to resemble a rapid series of aftereffects that exaggerate and distort the prominent dimensions of each successive face. The aim of this study was to investigate the strength of the FFDE with respect to the face-space model, specifically, whether distinctive faces appear more distorted in the paradigm. A multidimensional scaling (MDS) technique was employed to plot each of the faces in our set within a five-dimensional, and six-dimensional similarity space. The average distance from the centre of this space, was used as a measure of each face’s distinctiveness. Each face’s distortion was also measured in a 2AFC task where each face was alternated with the average face, in FFDE format. The results showed that greater facial distinctiveness was related to, and could predict, the faces that appeared more distorted in the FFDE. However, the variance explained by distinctiveness was small. Nonetheless, when the dimension relating to hair style was controlled for, predictive power increased. Response time in the distortion task was also unrelated to the relative distinctiveness between faces. Overall, the present study provided some support for the face-space model, and for the relationship between facial distinctiveness and distortion in the FFDE. It is likely that some distinctive facial dimensions are more associated with distortion than others. Limitations, particularly concerning low predictive ability, will be discussed, as will future directions for studying the FFDE.