Final answer:
The free-rider problem hampers interest group recruitment since potential members may benefit without joining. Interest groups offer material, solidary, and purposive incentives to overcome this. Examples include discounted services from AARP or increased ACLU membership motivated by civil liberties advocacy.
Step-by-step explanation:
The difficulty interest groups face in recruiting members due to the prospect that individuals may benefit from the work of these groups whether or not they join is known as the free-rider problem. This problem occurs because the goods or services that interest groups work to provide are collective goods, which means they are available to all, including those who do not contribute to the group's efforts. To combat the free-rider problem and entice individuals to join, leaders of interest groups may offer various types of incentives such as material incentives, purposive incentives, and solidary incentives. Examples include the AARP offering discounts on services, the ACLU experiencing a surge in membership after raising concerns about civil liberties, or individuals joining groups like the NAACP to connect with others who have faced similar issues of inequality.