Fig 6. Cortisol response to VFD exposure in relationship to the “vulnerability index”.

The vulnerability index inversely predicted cortisol change [F_(1,19) = 27.97, p < 0.0001; partial η2 = 0.59] (an effect size over four factors greater than a large effect size. Infant sex played no significant role in the relationship [F_(1,19) = 0.07, p = 0.78]. The red line represents a linear regression (r = -0.77; p <0.001; r² = 0.60).