Single-blind phase (phase II)
To examine whether the change from placebo to OT administration (in the placebo-first group) or a continuation of OT administration for another 4 weeks (in the OT-first group) may have induced differential changes in SRS-2 scores during phase II, change scores (from T2, the last session of phase I) were calculated and subjected to independent-sample t-tests with the between-subject factor ‘Phase I nasal spray’ (OT-first versus placebo-first). At assessment session T3 (immediately after the single-blind administration period), a significant effect of ‘Phase I nasal spray’ was evident, indicating that children who continued from the placebo nasal spray to the OT nasal spray showed stronger improvements in social responsiveness (Effects of oxytocin nasal spray administration on social responsiveness. Visualization of changes from baseline in caregiver-reported social responsiveness (SRS-2 total raw scores) of the double-blind phase (phase I) and the single-blind phase (phase II), separately for each original nasal spray group (oxytocin-first, placebo-first) and assessment session (immediate post (T1 and T3)and four-week follow-up (T2 and T4)). Lower scores indicate improvement. Vertical bars denote ± standard errorsAt the T4 follow-up session, the difference between the OT-first and placebo-first groups was no longer significant (Accordingly, as seen in Fig. 