What type of diffusion occurs when an innovative idea changes as it spreads outward from its hearth?

The correct answer is stimulus expansion diffusion. This type of diffusion occurs when an innovative idea originates in one location (the hearth) and spreads outward, but is adapted or modified in different areas before being accepted. Unlike contagious diffusion, where the idea spreads in a more uniform manner without alteration, stimulus expansion diffusion allows for the original concept to inspire changes that are tailored to fit the local culture or context.

For instance, a technology like mobile payment systems may initiate in one region but could evolve differently in different cultural or economic environments as it spreads. The communities may adopt the core idea of digital payments but might alter it to accommodate their needs, regulations, or preferences, resulting in diverse implementations of the original innovation. This adaptability is a central characteristic of stimulus expansion diffusion, setting it apart from other forms of diffusion, such as hierarchical expansion diffusion, which typically involves the spread of ideas from influential or authoritative figures to broader audiences, or contagious diffusion, where ideas spread rapidly and uniformly without local changes.