A STRIKING trend in todayâ€™s culture is the pursuit of rapid cognitive enhancement. The idea behind many popular video and online â€œbrain-trainingâ€ games is that practicing tasks that strengthen memory, attention and other mental processes will make you a smarter person.
Nintendo markets its Brain Age game as a â€œtreadmill for the mind.â€ Lumosity, which claims 20 million users, says that its brain-training games offer â€œreal-world cognitive benefits in individuals of all ages.â€ Cogmed, which has been adopted by schools in the United States and Sweden, helps its users â€œunlock their natural cognitive abilities by training their brain.â€ Forbes magazine recently declared cognitive enhancement the next â€œtrillion-dollar industry.â€ The United States military is even exploring the possibility of using such cognitive training to increase soldiersâ€™ capacities.
Why the craze? Until recently, the overwhelming consensus in psychology was that intelligence was essentially a fixed trait. But in 2008, an article by a group of researchers led by Susanne Jaeggi and Martin Buschkuehl challenged this view and renewed many psychologistsâ€™ enthusiasm about the possibility that intelligence was trainable â€” with precisely the kind of tasks that are now popular as games.
Yet I and many other intelligence researchers are skeptical of this research. Before anyone spends any more time and money looking for a quick and easy way to boost intelligence, itâ€™s important to explain why weâ€™re not sold on the idea.
In the Jaeggi study, the researchers began by having participants complete a test of reasoning to measure their â€œfluidâ€ intelligence â€” the ability to draw connections between things, solve novel problems and adapt to new situations. Then some of the participants received up to eight hours of training in a difficult cognitive task that required paying careful attention to two streams of information (a version of this task is now marketed by Lumosity); others were assigned to a control group and received no such training. Then all of the participants took a different version of the reasoning test.
The results were startling. The authors reported that the trained participants showed a larger gain in the reasoning test than the control group did, and despite the relatively brief period of training, this gain was large enough that it would be expected to substantially improve performance in everyday life.
Does this sound like an extraordinary claim? It should. There have been many attempts to demonstrate large, lasting gains in intelligence through educational interventions, with few successes. When gains in intelligence have been achieved, they have been modest and the result of many years of effort.
For instance, in a University of North Carolina study known as the Abecedarian Early Intervention Project, children received an intensive educational intervention from infancy to age 5 designed to increase intelligence. In follow-up tests, these children showed an advantage of six I.Q. points over a control group (and as adults, they were four times more likely to graduate from college). By contrast, the increase implied by the findings of the Jaeggi study was six I.Q. points after only six hours of training â€” an I.Q. point an hour.
Though the Jaeggi results are intriguing, many researchers have failed to demonstrate statistically significant gains in intelligence using other, similar cognitive training programs, like Cogmedâ€™s. The Web site PsychFileDrawer.org, which was founded as an archive for failed replication attempts in psychological research, maintains a Top 20 list of studies that its users would like to see replicated. The Jaeggi study is currently No. 1. While this is an indication of the interest among psychologists in the idea that cognitive training might produce remarkable gains in intelligence, it also reflects a widespread cautiousness toward the results of a single study.
Another reason for skepticism is a weakness in the Jaeggi studyâ€™s design: it included only a single test of reasoning to measure gains in intelligence. As the cognitive psychologists Zachary Shipstead, Thomas Redick and Randall Engle note in a recent review of the cognitive training literature in Psychological Bulletin, intelligence canâ€™t be measured with any single test; it reflects what tests of many cognitive abilities have in common. Demonstrating that subjects are better on one reasoning test after cognitive training doesnâ€™t establish that theyâ€™re smarter. It merely establishes that theyâ€™re better on one reasoning test.
We shouldnâ€™t be surprised if extraordinary claims of quick gains in intelligence turn out to be wrong. Most extraordinary claims are. But we shouldnâ€™t be totally discouraged, either. Results of studies like the Abecedarian project suggest that intelligence can be increased by making improvements in peopleâ€™s environments, and that this can improve peopleâ€™s lives.
But such studies also suggest that meaningful increases are not likely without a substantial commitment of resources. If we lose sight of this fact, this is a commitment we may never make.
David Z. Hambrick is an associate professor of psychology at Michigan State University.