Are we born with a single, generalized type of intelligence that simply expresses itself in different ways for different people? Or is there nuance to our natural neural structure? According to Gardner’s theory of multiple intelligences, there are actually eight cognitive categories that exist within the human mind, and our particular mental makeup depends on a combination of genetic factors and personal experience.

Cultivating a New Concept

When Howard Gardner was a child, he discovered a strange dichotomy. While identifying pieces of music and learning new instruments came naturally to him, he struggled with visual patterns. After decades of education — including a B.A. from Harvard in social relations, a Master’s degree from the London school of economics and a Ph.D. in developmental psychology from Harvard — he came to the conclusion that, rather than having a single kind of intelligence, humans had eight distinct types. Theories of single-source intelligence, often called “g,” argued for a broad interpretation of Homo sapien smarts that relied on the same basic processing mechanism to produce unique results.

However, in his book “Frames of Mind: The Theories of Multiple Intelligences,” Gardner suggested that human beings have differing ways of processing information, and these processing mechanisms are relatively independent. To help cultivate his new concept and prevent the number of potential intelligences from getting out of hand, he developed eight key “inclusion criteria” that any prospective processing paradigm must satisfy before making the cut:

1. Potential isolation via brain damage — Can the intelligence function remain even after brain damage, effectively making it “independent” of other cognitive conditions?
2. Evolutionary history and plausible function — Is there evidence of the intelligence in evolutionary history? Does it (or could it) serve a useful function in society?
3. Identifiable operations — How does the intelligence operate? What sets it apart from other types in terms of acquisition and demonstration?
4. Symbol encoding ability — What type of symbol encoding ability does the intelligence leverage? (i.e. numbers, musical notes, words, pictures, etc.)
5. Defined developmental history — How does the intelligence type develop over time, and how does it manifest at varying life stages?
6. Existence of savants — Are there savants who display extraordinary faculty in the specific intelligence type? Mozart or Beethoven might be considered musical intelligence savants, while Einstein could be classified as a logical-mathematical savant.
7. Support from experimental psychology — Are there experimental efforts that support this type of intelligence at scale? For example, recent research has uncovered the existence of more than 500 “intelligence” genes in humans, which could help to map some of Gardner’s mental models.
8. Support from psychometric research — Is there evidence of rigorous and repeatable psychological testing that demonstrates the existence of a specific intelligence type?

The creation of these eight criteria helped to add rigor to Gardner’s research and formed the basis of the eight intelligences he defined.

Exploring the Eight Intelligences

Using his eight criteria, Gardner defined eight types of intelligence:

1. Linguistic (word smart) — Word smart individuals have a propensity for reading, writing and understanding language. Savants may be great writers or orators and have the ability to quickly grasp key concepts that are presented orally or in writing.
2. Logical-mathematical (number smart) — Number smart individuals have a natural ability for math and logic puzzles and are often able to conceptualize and solve abstract problems with ease.
3. Spatial (picture smart) — Picture smart people are able to recognize key visual features at both small and large scale. As a result, highly spatial individuals may find themselves drawn to pursuits such as sculpting or chess at smaller scales and careers such as architecture or airline pilots at larger visual volumes.
4. Bodily-kinesthetic (body smart) — Great athletes are body smart, since they have the ability to easily coordinate multiple body parts or their entire body to achieve a specific goal — often without conscious thought. Combined with spatial intelligence, bodily-kinesthetic individuals may also excel at the design and building of complex products or systems.
5. Musical (music smart) — Abilities such as “perfect pitch” are often exhibited by those with musical intelligence. They’re also able to recognize and repeat songs with only minor auditory exposure, and savants in this area often go on to become stellar instrumentalists or great composers.
6. Interpersonal (people smart) — Interpersonal intelligence provides the ability to understand other people — what they’re thinking and feeling and what motivates them to perform specific action. Highly interpersonal people may end up working in “helper” positions such as healthcare or take on roles as political leaders.
7. Intrapersonal (self smart) — Self-smart individuals are introspective and intimately aware of their own internal processes. Coupled with linguistic or spatial intelligence, this can lead to works in written or visual art or drive the development of new philosophical discourse.
8. Naturalist (nature smart) — The last intelligence type to make Gardner’s list is that of nature smart individuals who have the ability to identify and understand natural phenomena, such as Charles Darwin or David Attenborough.

Gardner noted that the first two categories — linguistic and logical-mathematical — are often tested in educational settings and valued highly in society at large, while the other types exist on the fringes of mainstream existence. Standardized testing and common learning delivery methods highlight this unintentional bias; Gardner’s theory has therefore been transformative for many educational approaches.

It’s also worth noting that these intelligences don’t exist in isolation. Instead, they appear by degrees — most people will display substantive strength in one or two categories, average aptitude in most others and struggle with the concepts of several. For Gardner, visual intelligence was challenging; he was unable recognize common objects from shadow silhouettes during a game in his childhood and “resolved at that time never to participate in any competition that featured the recognition of visual patterns.”

Along with the eight listed here, other potential candidates — including moral, spiritual and existential intelligence — have also been studied by Gardner, but they haven’t been able to satisfy his eight consideration criteria.

Embracing the Growth Mindset in Education

While Gardner’s theory of multiple intelligences has faced ongoing challenges from other academics who see it as either too broad or too narrow, the concept has been widely embraced by education professionals as a way to improve student experiences and outcomes. As the American Institute for Learning and Human Development notes, Gardner’s work “proposes a major transformation in the way our schools are run.” Instead of considering every student as a subset of the generalized “g” intelligence and assuming they’ll all respond equally well to standardized teaching methods, the multiple intelligences approach suggests the need for more nuanced education that plays to student strengths.

According to Simply Psychology, Gardner was surprised by the rapid uptake of his theory by education professionals, since the original framework was designed to spur discourse and debate among his academic colleagues. In fact, this academic approach set the stage for instructional use; since his work offered a generalized structure rather than suggesting practical applications, educators were free to adapt the theory as they saw fit. However, Gardner often declined offers to expand his work into education, preferring instead that teachers and students act as the driving force for in-classroom development.

It’s worth noting that, despite their similarities, Gardner’s intelligences and so-called “learning styles” are not the same thing. While they share common concepts, such as the notion that students may be predisposed to auditory, visual or kinesthetic education, they lack the same rigor in terms of criteria and classification. As a result, these learning styles may be better thought of as generalized approaches to Gardner’s more specific categories — but they’re not interchangeable.

Lasting Legacy

Accept the theory of multiple intelligences or reject it outright, Howard Gardner remains a paragon of American developmental psychology. Today, he’s the John H. and Elisabeth A. Hobbs research professor of cognition and education at the Harvard Graduate School of Education, the senior director of Harvard’s Project Zero, which focuses on the understanding and enhancement of learning, thinking and creativity, and the co-director of The Good Project, which focuses on “encouraging ethical, excellent and engaging work.”

In other words, Gardner’s outside-the-box thinking persists as he continues to dive deeply into both the framework and functionality of human intellect and the incredible potential of human intelligence.