句中的 in 表示时间，意思是“当……的时候”。

in deciding = when deciding。

又如：

Be careful in crossing the street. 过街道要小心。

He had a hard time in getting here. 他来这儿一路很辛苦。

In crossing the street he was run over. 他在穿过马路时被汽车撞倒。

You should be careful in operating this machine.  操作这部机器时要小心。

In studying other cultures, you can learn more about your own. 当你学习其他文化时，你能学到更多有关自己的文化。