To find out they recruited two participants willing to put in 29 hours of practice over a 6 week period: Diane and John were their volunteers (Spelke, Hirst &Neisser, 1976).

• 为了找出答案，他们雇佣愿意在6周里投入29个练习小时的两位参与者：Diane和John成为了他们的自愿者（Spelke；Hirst&Neisser；1976).