When the experimenters repeated the tests on themselves, they observed an exactly opposite effect.当实验者在自己身上进行检测时，他们观测到了完全相反的结果。Experimenters have succeeded in controlling the rate and regularity of the heartbeat.实验者已经成功控制了心跳的速度和频率。She was the first human guinea pig for the vaccine.她是这个疫苗的第一个人体实验者。