3. Max, is a 9-month-old infant who is playing with his older sister, Emma. Emma is playing with her favorite doll and Max also wants to play with it. So, Emma hides it underneath a blue blanket. Max...

3. Max, is a 9-month-old infant who is playing with his older sister, Emma. Emma is playing with her favorite doll and Max also wants to play with it. So, Emma hides it underneath a blue blanket. Max immediately finds it. Emma hides it again under the blue blanket and Max finds it again. Then Emma hides it under a yellow blanket. Max looks for the doll under the blue blanket again. Max is demonstrating which aspect of the sensorimotor stage?