the tendency for people to reduce their efforts when working as part of a group is called

Social loafing

Explanation:

Social loafing is a phenomenon in which a person exerts less effort when working in a group than he would if working alone. This is often caused by the fact that people believe their effort does not matter when in a group, whihc leads them to try less hard. This is one reason why groups tend to be less productive than the same individuals working on their own.

would it be plagiarism to copy and paste off of here? ?