FEELING a little less mentally quick than you did a few years ago? Maybe you are among the many people who do “brain exercises” like sudoku to slow the cognitive decline associated with aging. We’ve got a better suggestion.

Computer programs to improve brain performance are a booming business. In the United States, consumers are expected to spend $80 million this year on brain exercise products, up from $2 million in 2005. Advertising for these products often emphasizes the claim that they are designed by scientists or based on scientific research. To be charitable, we might call them inspired by science — not to be confused with actually proven by science.

Environmental enrichment does improve mental function in laboratory animals. Rodents and monkeys that get playmates or toys learn to complete a variety of tasks more easily, at all ages. They also have larger brains, larger brain cells and more synaptic connections than animals raised alone in standard cages. But here’s the rub: standard laboratory environments are tremendously boring. Lab animals rarely need to search for food or avoid predators. In contrast, most of us get plenty of everyday stimulation in activities like finding a new address, socializing with friends or navigating the treacherous currents of office politics. Animal enrichment research may be telling us something important not about the positive effects of stimulation, but about reversing the negative effects of deprivation.

Another line of evidence cited by marketers comes from studies of elderly people who improve certain skills by practicing a challenging computer-based task. Although most programs work to some extent, the gains tend to be specific to the trained task.