Figure 3.

Mean suprathreshold contrast matching functions for reference stimulus contrasts two times (a) and four times (b) the detection threshold. Vertical axes show the ratio between matched and reference contrasts (matched contrast ratio = matched contrast/reference contrast). Horizontal dashed lines indicate where matched contrast equals physical contrast (matched contrast ratio = 1.0). Symbols are coded as in Figure 2, except that the grey triangle with dashed error bars represents the data for the four participants with glaucoma able to complete the 4 c/deg condition at four times the detection threshold. These data were excluded from statistical analysis and are included here for reference only. Error bars show 95% confidence interval of the mean. VF, visual field.