Additionally, Figure F shows higher median wages in states with strong labor unions: Michigan, Ohio, Pennsylvania, Wisconsin, California, and New Jersey, for example. Historically, there has been a strong correlation between union density—the percent of a state’s workforce represented by a union—and state median wages. 3 Today there are no states with the levels of union density that the high-wage states had in the late 1970s. Not surprisingly, the share of corporate revenue that is paid in wages rather than distributed in profits has declined significantly (Jacobson and Occhino 2012). Unions now represent a much smaller share of the workforce than they did in the decades immediately following World War II and so are not the force that they were for creating middle-class jobs for large numbers of workers with a high school education or less.
The principle underlying most memory techniques is that our brains don’t remember every type of information equally well. Like every other one of our biological faculties, our memories evolved through a process of natural selection in an environment that was quite different from the one we live in today. And much as our taste for sugar and fat may have served us well in a world of scarce nutrition but is maladaptive in a world of ubiquitous fast-food joints, our memories aren’t perfectly suited for our contemporary information age. Our hunter-gatherer ancestors didn’t need to recall phone numbers or word-for-word instructions from their bosses or the Advanced Placement . history curriculum or (because they lived in relatively small, stable groups) the names of dozens of strangers at a cocktail party. What they did need to remember was where to find food and resources and the route home and which plants were edible and which were poisonous. Those are the sorts of vital memory skills that they depended on, which probably helps explain why we are comparatively good at remembering visually and spatially.