Experimental procedure
Autism
Participants were first asked to complete Chinese versions of validated questionnaires on personality, traits, mood, attitude toward interpersonal touch and sensitivity to reward to control for possible group differences in potential confounders. Personality trait measures included the Autism Spectrum Quotient (ASQ; Following completion of the questionnaire assessments, participants were randomly assigned to receive the oral (lingual) or intranasal administration of OT spray (24 IU; Oxytocin Spray, Sichuan Defeng Pharmaceutical Co. Ltd, China) or their corresponding placebo (PLC) spray (half received the PLC intranasally and half orally; identical ingredients except the peptide - i.e. glycerine and sodium chloride) in a randomized double-blind placebo-controlled between-subject design. Intranasal and oral spray bottles and OT concentrations per 0.1 ml puff were identical (i.e. 4 IU). For intranasal administration, three puffs were applied to each nostril alternating between them and with 30 s between each puff, for oral administration six puffs were sprayed onto the tongue (i.e. lingual) with 30 s between each puff and the subjects required not to swallow until just before the next puff was applied to allow time for absorption by oral blood vessels (as in In line with previous studies (Immediately after each session, subjects completed the PANAS and then answered the following four questions: (1) How pleasant did you feel the massage? (1=extremely unpleasant, 9=extremely pleasant). (2) How much did the massage arouse you? (1=drowsy and unresponsive, 9=very arousing). (3) How intense was the massage? (1=extremely light, 9=extremely strong) and (4) How much would you be willing to pay if you had to pay for the applied massage? Please choose from 1 to 100 (1=1 RMB, 9=100 RMB). After the experiment, participants were asked to guess the gender of the massager to control for possible sex-dependent effects.