Sequence of experimental conditions in the two subject groups.

aEach condition in the sequence was tested twice on two consecutive nights, with the position of the test and standard feeder exchanged. In Group 1, the experiment was interrupted for 4 days between sequence 14 and 15 and in Group 2 for 8 days between sequence 7 and 8.bSugar solution concentrations are given in % weight/weight. The concentration of the standard was always 20% w/w.cRelative intensity is calculated as the absolute difference between the test and standard concentrations divided by the average of the concentrations.dNumbers given in bold correspond to the HIGH data set (test concentrations equal to or larger than 20%). The rest of the numbers correspond to the LOW data set. The comparison with 20% was included in both data sets. As the R script for psychometric analysis did not accept the 0 intensity value, it was entered as 1.0×10−6 instead.