Final answer:
Disturbance theory posits that interest groups form in response to societal changes or external events, termed as 'disturbances.' The theory, developed by David Truman, explains how these events cause people to mobilize collectively to protect or advance their interests, influencing policy and societal norms.
Step-by-step explanation:
Disturbance theory is a political theory brought forth by Columbia University professor David Truman. It suggests that interest groups form in response to changes or external events in society, which Truman refers to as 'disturbances.' These disturbances can include alterations in social norms, environmental factors, technology, and more. For example, social and medical norms about cannabis have led to the creation of groups like NORML and the Drug Policy Alliance. Similarly, a notable disturbance in the environmental sector was Rachel Carson's publication of Silent Spring, which heightened public awareness and led to the formation of several environmental interest groups. Disturbance theory also aligns with the idea that when people sense their interests are at risk due to external events, they are more likely to mobilize collectively. This theory forms part of the basis of how we understand collective action in the political, economic, and social environments. It's through these moments of mobilization and the subsequent influence of interest groups that policy and societal norms can change over time.