“…Various metrics of the detectability of symmetry in a stimulus have been proposed (see, e.g., Chipman, 1977;Dakin & Watt, 1994;Dry, 2008;Masame, 1986Masame, , 1987Yodogawa, 1982;Zimmer, 1984), and two things are pretty clear. First, a simple cross-correlation of the two symmetry halves does not seem to agree with human symmetry detection (see, e.g., Barlow & Reeves, 1979;Tapiovaara, 1990).…”