Finally, to examine the extinction of saccadic adaptation, defined as the return to baseline gain, the gain change at the end of the postadaptation phase was calculated relative to pre-VF baseline. In the group of children, eight of nine showed a shorter saccade gain at the end of the postadaptation phase relative to the baseline (individual
t-tests < 0.05). Only one child (c4) showed full extinction of adaptation, signaled by the return to baseline gain. In the group of adults, five of nine (a1, a2, a4, a5, a7) showed a full extinction of adaptation (i.e., return to baseline gain, individual
t-tests > 0.05). As shown in
Figure 3C, patterns of extinction were heterogeneous for both adults and children. On average, the amount of gain change [formula = (VF preadaptation gain − VF postadaptation gain) /VF preadaptation gain] did not differ between adults and children (5.3 ± 5.6% and 6.4 ± 5.5%;
P > 0.6). Because individual analyses suggested a difference in the extinction of adaptation between children and adults, this pointed to the fact that extinction was not complete at the end of the postadaptation phase relative to the baseline for most of the children. Are their saccade gains at the end of the postadaptation phase different from those at the end of the adaptation phase? At the individual level (
t-tests < 0.05), five of the eight children who did not show the extinction of adaptation (no return to baseline) had a greater saccade gain at the end of the postadaptation phase than at the end of the adaptation phase (
Fig. 3D, right panel). This extinction was starting in almost all adults in the study, as shown in
Figure 3D (left panel). On average, the difference between the two groups did not reach significance (
P > 0.09).