Do Numbers Constitute a Sixth Sense?
Numbers may be a sixth sense and the basis for abstraction and symbolism.
Posted May 19, 2026 | Reviewed by Lybi Ma
Traditionally, humans are said to have five senses: vision, hearing, taste, smell, and touch. But what if there is a sixth sense? Although extrasensory perception (ESP) is often proffered as the sixth sense, the actual consistent empirical evidence is so weak or non-existent as to make that supposition highly questionable. However, what if a sixth sense lies not in ESP or some mystical perception, but in something far more fundamental and demonstrable: humans’ innate sense of numbers?
What Makes a Sense Primary ?
First, what qualifies a sense as primary? The traditional senses share a key feature: They are hardwired. People don’t teach their children what sweetness is or how to distinguish red from blue: We simply give names to experiences we already possess. Dedicated brain neurons process human senses automatically, innately, and without learning or instruction.
I argue our sense of numbers works the same way. We don’t truly teach children to recognize “one,” “two,” or “three” things: We are simply giving names to an ability that is innate, like the word one, uno, eins, etc . And like the five classic senses, numbers also have a dedicated neural architecture. A lower region of the parietal lobes (intraparietal sulcus or IPS) has neurons genetically programmed and dedicated to detecting the ‘oneness,’ ‘twoness,’ or ‘threeness’ of many things—be they stones, bones, tones, or mythical things like unicorns. This ability has been empirically demonstrated in human infants (in a very unique research paradigm) and in monkeys. Therefore, this appreciation of numbers is independent of language.
This specific differentiation ability is called subitization , which comes from the Latin word meaning sudden . Subitization is one of the two core processes of numerosity , the appreciation and basic understanding of numbers. The other core process is the ability to quickly compare and understand the differences between a small set of things and a larger set—again, any things , be they sticks, apples, or material representations of angels.
This core process has been called fuzzy set comparison or magnitude set appreciation. It is fuzzy in the sense that one may not know the exact number of apples in this tree, but one knows immediately that another tree has more apples. One interesting tangential task: Ask your favorite mathematician or any mathematician if they know what numerosity is. Most do not, as it is a concept far more popular in cognitive psychology and the cognitive neurosciences.
Ancient Evidence for Numerosity
Prehistoric calculating devices, such as the tally-marked bone plaque from the Abri Blanchard site in France , dating to about 32,000 years ago, demonstrate that humans have been expressing numerical ideas for tens of thousands of years. And since monkeys have been empirically shown to demonstrate the two core processes of numerosity, it means that evolutionarily, this skill is probably much older than 20,000,000 years, from the time when the great apes (our lineage) and monkeys diverged. In addition, octopuses can demonstrate some aspects of numerosity, which would push back number appreciation to at least 275,000,000 years ago!
Numbers as the Root of Abstract and Symbolic Thought
My former M.A. student (and now a Ph.D. student at Oxford University) and I have previously argued (Coolidge and Overmann, 2012) that numerosity may be the evolutionary foundation of all abstract and consequently symbolic thinking. We also considered numerosity the “Ur-Metaphor” as numbers may represent any thing in the world. We argue that the cognitive leap of treating a quantity as a real, manipulable entity is itself a metaphoric act, and it is no mere coincidence that the IPS that houses numerosity is also linked to metaphor production and comprehension.
Embodied Cognition and Finger Counting
Finger counting, far from being a childish habit, may be the bridge between our innate number sense and higher mathematical thought. By physically mapping quantities onto fingers, children instantiate the abstract concepts of number sequence, ordinality (position in a sequence), and cardinality (how many in a set) using their bodies. This is a form of embodied cognition , which is the way the mind extends itself into the physical world and ‘leaks’ far beyond the confines and limits of our skulls. Things in the material world help scaffold our cognitive processes and ultimately allow the release of higher cognitive and mathematical concepts, like geometry, algebra, calculus, and ideas like prime numbers.
Numbers are not a simple cultural invention imposed on a tabula rasa . I hypothesize that they are sensed and perceived, just like our other senses of color, sound, taste, smell, and touch. The classic five senses and numerosity are innately instantiated by the brain’s neurons. In this light, numerosity deserves its place alongside vision, hearing, taste, smell, and touch, as one of the fundamental ways humans make sense of the world.
Coolidge, F. L., & Overmann, K. A. (2012). Numerosity, abstraction, and the evolution of symbolic thinking. Current Anthropology , 53 (2), 204-225.
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Frederick L. Coolidge, Ph.D. , is Professor of Psychology at the University of Colorado, Colorado Springs.
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