Light emitting diodes and the lighting revolution: The emergence of a solid-state lighting industry

Emergence of new industries from evolving technologies is critical to the global economy, yet has been relatively understudied due to the paucity of available data. This study draws lessons on industry emergence, by analyzing how a solid-state lighting (SSL) industry grew out of light emitting diode (LED) technologies that evolved for half a century, with participation by tens of thousands of researchers in universities, national laboratories, and firms. Using data on publications, patents, and firms combined with business history we trace the evolution of SSL through a succession of market niches. At times a few researchers with unorthodox research approaches made breakthroughs that greatly advanced particular technology trajectories and pushed LED research in unexpected directions. A succession of LED market niches advanced the technology and provided profits to incentivize continuing research while reducing cost and improving efficacy of LEDs. Innovating firms developed a thicket of patents and captured substantial profit, but were embroiled in extensive litigation that was ultimately resolved through cross-licensing. A major new generation of lighting products is now disrupting the traditional lighting industry. Although the leading incumbent lighting firms all invested early and heavily in SSL, the industry's future leadership is uncertain.     

Population differences in constructive memory

An experiment was conducted to evaluate constructive memory in fourth-grade low-SES black and middle-SES white children. The children were read nine short passages; each passage was composed of two premise statements and a filler sentence. The children were tested by a recognition procedure. Thirty-six test sentences were presented randomly. Four sentences were associated with each passage (true premise, false premise, true inference, and false inference). Subjects were asked to make yes/no recognition decisions based on whether the test sentence was identical to a sentence presented at study. Middle-SES white children made few errors, except to true inference test sentences. This pattern of performance is consistent with the constructive view of memory. Low-SES black children also had a high error rate to true inference items. However, this outcome may not reflect constructive memory because they also had a high error rate to some of the other types of test sentences.