It’s been 30 years since the theory of multiple intelligences was proposed by Dr. Howard Gardner, professor of education at Harvard University. The “eight intelligences,” which ranged from bodily-kinesthetic intelligence to naturalist intelligence, explained why students could succeed at one type of task and fail at others. Teachers started regarding their students as having different intelligences not based on a general quotient but rather on individual capacities, and adult learners began examining potentials they’d left behind in childhood but now had the opportunity to develop through courses, hobbies, or other programs of self-development.

And that’s as far as the theory should have been taken.

Unfortunately, much like the learning styles theory and the right-brain-left-brain paradigm, multiple intelligences has skyrocketed into popularity while oversimplifying the nature of the human brain and further pigeonholing students into narrow categories.

“Why,” asks Daniel T. Willingham, professor of psychology at the University of Virginia, “are we referring to musical, athletic, and interpersonal skills as intelligences?”

Gardner himself has noted on several occasions that the success of his first book on MI rested, in part, on this new label: “I am quite confident that if I had written a book called “˜[Eight] Talents’ it would not have received the attention that Frames of Mind received.”

The term intelligence has always connoted the kind of thinking skills that make one successful in school, perhaps because the first intelligence test was devised to predict likely success in school; if it was important in school, it was on the intelligence test.

“Readers made the natural assumption that Gardner’s new intelligences had roughly the same meaning and so drew the conclusion that if humans have a type of intelligence, then schools should teach it,” Willingham says.

What’s more, Gardner’s new definition self-consciously broadened the concept to include effective use of the body and thinking skills relevant to the social world. In Frames of Mind Gardner describes intelligence as “a biopsychological potential to process information that can be activated in a cultural setting to solve problems or create products that are of value in a culture.” Previous definitions had been limited to cognition or thought; one was intelligent to the extent that one could solve problems and adapt effectively to one’s environment using thinking skills. The body had no part in the matter.

But what we’ve missed, over the years, is that Gardner’s eight “intelligences” were never scientifically proven to be anything more than talents, preferences, and skills.

“Too many of the categories correlate too highly with one another to be separate intelligences,” says Christopher J. Ferguson, associate professor of behavioral and applied sciences at Texas A&M International University. “Cognitive performance on skills related to verbal-linguistic, logical-mathematical, and visual-spatial tasks, as well as many memory tasks, tends to be highly related.”

[Editor’s Note: Read more about neuroducation here.]

Only bodily-kinesthetic – the ability to manipulate one’s own body with dexterity – may truly represent a separate cognitive ability, probably stemming from cerebellar activity involved in fine motor control, he says. But it may be better represented as a neurophysiological trait than as intelligence.

In addition, despite its widespread popularity, the success of multiple intelligences theory as a teaching method is backed by very little hard data.

The most comprehensive study into the effectiveness of MI was a three-year examination of 41 schools that claim to use multiple intelligences. It was conducted in the early “˜90s by Mindy Kornhaber, a long-time Gardner collaborator. The results showed that standardized test scores increased in 78 percent of the schools, but Willingham says the scientific integrity of the study is questionable.

First, the results failed to indicate whether the increase in each school was statistically significant. If they weren’t, Willingham notes, then we would expect scores to increase in half the schools by chance anyway.

Second, there was no control group and thus no basis for comparison with other schools in their districts. Moreover, there is no way of knowing to what extent changes in the school were actually due to the implementation of MI. The energizing thrill of adopting a new school-wide program, new statewide standards, or some other unknown factor could just as easily have improved the quality of teaching.

The sheer fact that the theory is an inaccurate description of the mind, says Willingham, means that the more closely an educator draws on the theory, the less likely the educator is to be successful.

What About Learning Styles’ Success Stories?

The story is similar when it comes to learning styles theory, one of the most popular and widely adopted paradigms of the century.

In a controversial report from the journal of Psychological Science in the Public Interest (2009), Harold E. Pashler, a professor of psychology at the University of California at San Diego, wrote, “The contrast between the enormous popularity of the learning-styles approach within education and the lack of credible evidence for its utility is, in our opinion, striking and disturbing. If classification of students’ learning styles has practical utility, it remains to be demonstrated.”

The report was based on an exhaustive study of learning styles literature, aimed at finding empirical evidence for the validity of the theory. The panel concluded that an adequate evaluation of the learning styles hypothesis – the idea that optimal learning demands that students receive instruction tailored to their learning styles – required a particular kind of study. Specifically, students should be grouped into the learning style categories that are being evaluated (e.g. visual learners vs. verbal learners), and then students in each group must be randomly assigned to one of the learning methods (e.g. visual learning or verbal learning), so that some students will be “matched” and others will be “mismatched.” At the end of the experiment, all students must sit for the same test. This way, if the learning style hypothesis is correct, then, for example, visual learners should learn better with the visual method, whereas auditory learners should learn better with auditory method.

The panel found that studies utilizing this essential research design were virtually absent from the learning styles literature. In fact, the panel was able to find only a few studies with this research design, and all but one of these studies were negative findings – that is, they found that the same learning method was superior for all kinds of students.

But why do so many learning styles studies show positive effects? Hundreds of studies that do not meet Mr. Pashler’s stringent criteria for experimental design suggest – at least loosely – that students do better when instructors are trained in learning-styles theory.

One possibility, writes the Chronicle of Higher Education, is that the mere act of learning about learning styles prompts teachers to pay more attention to the kinds of instruction they are delivering. An instructor who attends a learning-styles seminar might start to offer a broader mixture of lectures, discussions, and laboratory work – and that variety of instruction might turn out to be better for all students, irrespective of any “matching.”

“Even though the learning-style idea might not work,” says Richard E. Mayer, a professor of psychology at the University of California at Santa Barbara, “it might encourage teachers to think about how their students learn and what would be the best instructional methods for a particular lesson.”

[Editor’s Note: Read more about other learning strategies here.]

The same may be said for multiple intelligences theory.

Science: Inspiration or Guide?

So how do you balance the lack of scientific evidence with the presence of practical evidence? Willingham says there are two primary methods by which educators might use science to inform practice.

On the one hand, you can operate under the belief that scientific evidence on learning is consistent with how you teach. “Teachers inevitably have a theory – implicit or explicit – of how children learn,” he writes. “This theory influences choices teachers make in their practice. If you believe that science provides a good way to develop and update your theory of how children learn, then the harmony between this theory and your practice is one way that you build your own confidence that you’re teaching effectively.”

It would seem, then, that if you don’t see the scientific proof for a theory, you shouldn’t practice that theory. But it’s not that simple.

“It’s possible to have effective practices motivated by a theory that lacks scientific support. For example, certain acupuncture treatments were initially motivated by theories entailing chakras – energy fields for which scientific evidence is lacking. Still, some treatments motivated by the theory are known to be effective in pain management.”

Which leads us to the second method: Although multiple intelligences theory may lack scientific evidence, it is not necessarily going to lead to bad practice. However, it is advisable to use it as inspiration, not a guide.

“In talking with teachers, I think this second method is probably more common.” Teachers treat multiple intelligences theory not as sacred truth about how students learn, but as a way to “prime the creativity pump, to think about new angles on lesson plans.”

“We need to take extreme care when moving from the lab to the learning environment,” says John Geake, Professor of Education at the UK’s Oxford Brookes University and a research collaborator with Oxford University’s Centre for Functional Magnetic Resonance Imaging of the Brain. “We do remember things visually and aurally, but information isn’t defined by how it was received.”

And neither should learning theory.