Emanuel is babysitting his 8-month old brother and 4-month old niece. The kids had been playing with blocks for a while when it was time to stop and pick up before having a snack. Emanuel gathers up the toy blocks, places them back in the toy chest, and closes the lid. Both children wanted to continue playing and were upset as Emanuel was taking the blocks away. However, Emanuel noticed his brother and niece behaved differently in response to the blocks being put into the toy chest. His brother crawled to the toy chest and pointed to the lid, but his niece reached out for other toys near her and quickly forgot the blocks. The kids' different responses most likely reflect differences in: