Fig. 5

The correlation between ∆ grill cold, i.e. the change in cold intensity from the 20 °C to the thermal grill condition (20/40 °C) and the intensity of cold during the 20 °C condition (a). The correlation between the ∆ grill warm, i.e. the change in warm intensity from the 40 °C to the thermal grill condition (20/40 °C) and the intensity of warmth during the 40 °C condition (b). A positive number on the y-axis indicates an increase in cold or warm sensation during the thermal grill stimulation compared to the uniform cold (20 °C) or warm (40 °C) stimulus, respectively. A negative number indicates the opposite, i.e. a decrease. Data of male (N = 58) and female (N = 78) subjects are presented separately using different symbols and colours. As values of thermal intensity ratings were not normally distributed (Kolmogorov-Smirnov test), Spearman’s correlation coefficient ρ was calculated. P < 0.05 after Bonferroni’s correction was considered significant and this is indicated by asterisks