Human beings have evolved a highly sophisticated capacity to receive and process information from their surrounding environment. While most of us take our traditional five senses for granted, there are individuals who function with fewer than five, yet what they are able to achieve with the senses they do possess borders on a precociousness that seems superhuman.
Take for example the case of Ben Underwood. Born with a form of cancer that necessitated complete surgical removal of his eyes at the age of 2, Ben learned how to see without sight using human echolocation. Similar to the ability of bats and dolphins, he was able to gain detailed information about his immediate environment using a series of audible clicks that served as a type of sonar. A battery of tests determined that his hearing had not increased in sensitivity or range; in fact, his audible range was not distinguishable from sighted human beings. What had changed was his ability to process the sounds he heard to provide information about the distance of an object, its size, and density. This ability was so refined he was able to navigate unfamiliar terrain with an alacrity and confidence comparable to that of individuals with intact vision. Importantly, blindness is not a causative pre-requisite for human echolocation; it can be developed and taught to others. In demonstration of this, Tim Johnson, a fully sighted individual, underwent a self-imposed regimen to develop his echolocation ability, providing evidence that a lack of sight from congenital or surgical causes is not the only way to bring such latent abilities out.
This example of compensatory potential is a fascinating look at the resilience of the human brain, and provides a glimpse into one aspect of a greater repertoire of dormant yet accessible parahuman abilities. Similar neurophysiological re-wiring can occur with other instances of a disrupted sensory modality. For example, deaf individuals recruited as part of a study to determine if their brain underwent any major changes revealed altered neural architecture as a result of their hearing loss. Significantly, scientists discovered that these individuals had an increased peripheral field of vision, and demonstrated evidence of enhanced motion processing as well as increased sensitivity to movement and luminance in their expanded field of view.
In an example of experimentally enhanced sensory compensation, individuals with no prior training in Braille were blindfolded prior to undergoing rigorous Braille instruction. Subjects who had been deprived of visual stimulation for five consecutive days developed a tactile sensitivity that allowed them to learn Braille faster than individuals who were not blindfolded. Furthermore, in a series of brain scans that analyzed which regions were most active during this period, regions within the visual cortex began to show activity associated with the tactile stimulation from their Braille sessions. To provide further evidence of the connection between heightened touch and the region of the brain that “sees”, a technique called transcranial magnetic stimulation (TMS) was used to temporarily block the function of the visual cortex; researchers found that this diminished the ability of blindfolded subjects to learn and read Braille, compared to when their brains were not inhibited. The overall conclusion drawn from this study was that the brain possesses a latent capacity to broaden the dynamic range of the remaining senses when one is lost or impaired. Furthermore, this ability to adapt does not necessarily involve forming new connections within the brain, just engaging pre-existing ones.
So, while these stunning augmentations have been demonstrated for hearing, vision, and touch, it would be reasonable to anticipate that all human senses have an innate capacity for super-adaptation, demonstrating that sometimes the most exciting mysteries lie not beyond our planet or in the depths of our oceans, but within our own bodies.