Developmental change, in Gladwell’s story, is behavior that occurs as people age. For instance, “murder is a young man’s game,” he said, with almost all murders being committed by men under the age of 25. Likewise, dying in a car accident is something that just “statistically doesn’t happen” over the age of 40. In other words, people age out of developmental changes — they are not true long-term lasting shifts in behavior.
Generational change, on the other hand, is different. That’s behavior that belongs to a generation, a cohort that grows up and continues the behavior. For example, Gladwell said, baby boomers transformed “every job in America” in the ’70s as they demanded more freedom, greater rewards, and changes in the boss-employee relationship.
The question is whether Snapchat-style behavior is developmental or behavioral.