Mean ± SD of JNDs for chromatic and luminance (achromatic) contrasts.

To determine whether T-shirts differed in their resemblance to the sexually-selected blue patches of male Sceloporus occidentalis, we calculated JNDs by comparing T-shirts to the throat patch and to the abdominal patch of lizards. To determine whether T-shirts differed in their detectability, we calculated JNDs by comparing T-shirts to the background environment from photographs taken within each study site.