When encouraged to eat their fill of m& m's, people ate more when given a large rather than a small serving scoop. this most clearly

unit bias                                                                                      

Explanation:

Bias: The term bias is defined as the propensity of an individual to get involved in taking action or to make decisions irrationally.

Unit bias: In psychology, the term unit bias is referred to as the propensity of an individual to desire to fulfill or complete a particular task or an item. An individual tends to complete the portion of work he or she is supposed to irrespective of size and create a perception to complete that satisfies him or her.

it gave them more rights