Dr. Gazzaley hosts a party in his San Francisco loft. There, he explains the “cocktail party effect”—the idea that at a party, where multiple streams of conversation are happening, you can only truly pay attention to one stream at a time. This demonstrates the limitations of attention: While you can control where you direct your attention, you can only focus it on one specific thing. Attention is “more like a laser than an overhead light” (62).

Up until the mid-19th century, it was initially believed that the brain was infinite in its capacity to process the stimuli of the world. However, Herman von Helmholtz performed experiments related to neural conduction time and discovered that it actually took time for current to travel to the brain—a factor that would necessarily limit the bounds of reaction time. Building on this work, in the 1860s, Francis Cornelius Donders of the Netherlands conducted a series of experiments on the circumstances that caused both shorter and longer human reaction times. He found that the more complex the task, the longer the reaction time, and the more likely it is for humans to make an error.

Back at his party, Gazzaley points out the creator of online virtual world Second Life wearing a Google Glass device, which can display a stream of information in your glasses.