Figure 1.

Experimental design. a, Example stimuli used in the study. Each column shows sample stimuli from an adult male block at a single morph level. During the experiment, six stimuli were shown in random order in a block. Note that in 0% morph the same face is shown and, as morph level increases, the faces in a block become more dissimilar. Rows illustrate how identity varies from the source to target face. b, Example stimuli show a block of 100% different female child faces in the top row and a block of 100% different female adult faces in the bottom row. c, Schematic of the face-morph space. Each source face was morphed into six target faces from the same gender and age along a straight morph line, with a linear weighting of the source and target faces. Each circle denotes stimuli shown in a block at each morph level. Morph level indicates percentage weighting of the target face.