By all appearances, we’re in a golden age of innovation. Every month sees new advances in artificial intelligence, gene therapy, robotics and software apps. Research and development as a share of gross domestic product is near an all-time high. There are more scientists and engineers in the U.S. than ever before.

None of this has translated into meaningful advances in Americans’ standard of living.

Economies grow by equipping an expanding workforce with more capital such as equipment, software and buildings, then combining capital and labor more creatively. This last element, called “total factor productivity,” captures the contribution of innovation. Its growth peaked in the 1950s at 3.4% a year as prior breakthroughs such as electricity, aviation and antibiotics reached their maximum impact. It has steadily slowed since and averaged a pathetic 0.5% for the current decade.

Outside of personal technology, improvements in everyday life have been incremental, not revolutionary. Houses, appliances and cars look much like they did a generation ago. Airplanes fly no faster than in the 1960s. None of the 20 most-prescribed drugs in the U.S. came to market in the past decade.

The innovation slump is a key reason the American standards of living have stagnated since 2000. Indeed, absent a turnaround, that stagnation is likely to continue, deepening the malaise that has left the middle class so dissatisfied.