“Your brain, just brighter,” is the slogan of Lumosity, an online company that now has some 25 million registered members. According to its Web site, “Our users have reported profound benefits that include: clearer and quicker thinking; faster problem-solving skills; increased alertness and awareness; better concentration at work or while driving; sharper memory for names, numbers and directions.”

 But are they better at math, science, engineering, english, philosophy, and civics?