Figure 4. The difference between core and forehead skin-surface temperatures (Delta T) at ambient temperatures (T^ambient) between 18 and 26 degrees Celsius. The data were fit to a second-order regression: Delta T =-0.58 + 0.29(T^ambient)- 0.01(T^ambient)², r²= 0.999. Each 1 degree Celsius change in ambient temperature, starting near 22 degrees Celsius, thus altered skin temperature [nearly equal] 0.16 degrees Celsius. Results are presented as means +/- SD. Horizontal error bars (variation in ambient temperatures) are not displayed because they were smaller than the size of the markers.