Each mother participated in three conditions. The ‘Voice’ condition required the participant to read either of two stories (Little Three Pigs [27 ] or Jack and the Beanstalk [28 ]) counterbalanced across all participants. In the ‘Touch’ condition mothers touched their abdomen as they usually would—stroking and rubbing the abdomen without interfering with the ultrasound probe and in the ‘Control’ condition mothers lay quietly with hands beside their bodies.
Each block began with a baseline period followed by the stimulus (touch, voice, control, depending on condition), followed by a second baseline period. Each section lasted for 3 minutes, thus each session lasted for 9 minutes, resulting in a total scanning time of 27 minutes per participant. The order of the three conditions was randomized and counterbalanced across all participants.