Humans Have a Lot More Than Five Senses

Daven Hiskey July 16, 2010 72
SensesToday I Found Out humans have a lot more than five senses.  It turns out, there are at least nine senses and most researchers think there are more like twenty-one or so.
Just for reference, the commonly held definition of a “sense” is “any system that consists of a group of sensory cell types that respond to a specific physical phenomenon and that corresponds to a particular group of regions within the brain where the signals are received and interpreted.

The commonly held human senses are as follows:

  • Sight:  This technically is two senses given the two distinct types of receptors present, one for color (cones) and one for brightness (rods).
  • Taste:  This is sometimes argued to be five senses by itself due to the differing types of taste receptors (sweet, salty, sour, bitter, and umami), but generally is just referred to as one sense.  For those who don’t know, umami receptors detect the amino acid glutamate, which is a taste generally found in meat and some artificial flavoring.  The taste sense, unlike sight, is a sense based off of a chemical reaction
  • Touch:  This has been found to be distinct from pressure, temperature, pain, and even itch sensors.
  • Pressure: Obvious sense is obvious. ;-)
  • Itch:  Surprisingly, this is a distinct sensor system from other touch-related senses.
  • Thermoception:  Ability to sense heat and cold.  This also is thought of as more than one sense.  This is not just because of the two hot/cold receptors, but also because there is a completely different type of thermoceptor, in terms of the mechanism for detection, in the brain.  These thermoceptors in the brain are used for monitoring internal body temperature.
  • Sound:  Detecting vibrations along some medium, such as air or water that is in contact with your ear drums.
  • Smell:  Yet another of the sensors that work off of a chemical reaction.  This sense combines with taste to produce flavors.
  • Proprioception:  This sense gives you the ability to tell where your body parts are, relative to other body parts.  This sense is one of the things police officers test when they pull over someone who they think is driving drunk.  The “close your eyes and touch your nose” test is testing this sense.  This sense is used all the time in little ways, such as when you scratch an itch on your foot, but never once look at your foot to see where your hand is relative to your foot.
  • Tension Sensors:  These are found in such places as your muscles and allow the brain the ability to monitor muscle tension.
  • Nociception:  In a word, pain.  This was once thought to simply be the result of overloading other senses, such as “touch”, but this has been found not to be the case and instead, it is its own unique sensory system.  There are three distinct types of pain receptors: cutaneous (skin), somatic (bones and joints), and visceral (body organs).
  • Equilibrioception:   The sense that allows you to keep your balance and sense body movement in terms of acceleration and directional changes.  This sense also allows for perceiving gravity.  The sensory system for this is found in your inner ears and is called the vestibular labyrinthine system.  Anyone who’s ever had this sense go out on them on occasion knows how important this is.  When it’s not working or malfunctioning, you literally can’t tell up from down and moving from one location to another without aid is nearly impossible.
  • Stretch Receptors:  These are found in such places as the lungs, bladder, stomach, and the gastrointestinal tract.  A type of stretch receptor, that senses dilation of blood vessels, is also often involved in headaches.
  • Chemoreceptors:  These trigger an area of the medulla in the brain that is involved in detecting blood born hormones and drugs.  It also is involved in the vomiting reflex.
  • Thirst:  This system more or less allows your body to monitor its hydration level and so your body knows when it should tell you to drink.
  • Hunger:  This system allows your body to detect when you need to eat something.
  • Magentoception:  This is the ability to detect magnetic fields, which is principally useful in providing a sense of direction when detecting the Earth’s magnetic field.  Unlike most birds, humans do not have a strong magentoception, however, experiments have demonstrated that we do tend to have some sense of magnetic fields.  The mechanism for this is not completely understood; it is theorized that this has something to do with deposits of ferric iron in our noses.  This would make sense if that is correct as humans who are given magnetic implants have been shown to have a much stronger magnetoception than humans without.
  • Time:  This one is debated as no singular mechanism has been found that allows people to perceive time.  However, experimental data has conclusively shown humans have a startling accurate sense of time, particularly when younger. The mechanism we use for this seems to be a distributed system involving the cerebral cortex, cerebellum, and basal ganglia.  Long term time keeping seems to be monitored by the suprachiasmatic nuclei (responsible for the circadian rhythm).  Short term time keeping is handled by other cell systems.

Bonus Facts:

  • The traditional “five senses” model (sight, hearing, touch, smell, and taste) is credited to Aristotle
  • One such method for testing whether humans have magentoception is by placing a strong magnetic field near a person and then disorienting them.  Results have shown that people in this scenario perform significantly worse at being able to re-orient themselves in terms of the cardinal points than people who are not near a strong magnetic field.  More conclusive evidence has been demonstrated by examining subject’s brains when magnetic fields are produced near a person.  It has been shown that these magnetic fields will evoke a response in the brain’s activity.
  • Numerous experiments have demonstrated that people do have the ability to detect accurately the passage of time.  One experiment showed that, without consciously counting or anything of the like, a group of 19 to 24 year olds were able, on average, to tell when 3 minutes was up within a 3 second margin of error.  Interestingly, the age group of 60-80 tended to average perceiving 3 minutes pass at around 3 minutes and 40 seconds consistently within the test group.  This would seem to indicate whatever mechanism we use to sense time slows as we age and thus as we get older time seems to pass faster to us.
  • People with Parkinson’s disease and ADD have severely impaired sense of time passage compared to “normal” people.
  • The vestibular labyrinthine system (equilibrioception) works by sensing the motion of fluid in three canals in your inner ear, as well as sensing the weight of small crystals of calcium carbonite on tiny hair-like sensory receptors.
  • Proprioception (sense of relative position of body parts) comes from the Latin “proprius”, meaning “one’s own”.
  • There exists a type of bacteria, called magnetotactic bacteria, that build magnets inside themselves in order to orient themselves with the Earth’s magnetic field.  They also migrate and form chains of themselves along magnetic field lines.
  • Many avian life forms posses a region of their bodies that contain a biological magnetite, generally in their beaks.  It is believed this gives them a strong magnetoception and thus allows them to sense direction accurately.  More recently, it has been shown that certain birds have the ability to see magnetic fields.  How this works is the Earth’s magnetic field effects how long a certain molecule, cryptochrome, in their photoreceptor cells stays in the active state.  This then affects the light sensitivity of the bird’s retinal neurons.  The net effect is the birds can perceive magnetic fields with their eyes.   The biological magnate and ability to perceive magnetic fields with their eyes are thought to combine to form a very accurate mapping and directional system in the birds.
  • Sharks, stringrays, and chimeara all possess an electroreceptive organ called an ampullae of Lorenzini.  This organ gives them the ability to detect even small variations in electric potential.  They can use this to detect magnetic fields, among other things.
  • Cattle tend to align themselves north-south, which leads some researchers to believe they have a strong magnetoception sense.
  • Some people experience something called synesthesia where they may perceive some sound and think of it as a color.  So a dog barking may be “red” to them or the like.  This condition does not generally occur naturally, though it can; it usually manifests itself when people are under the influence of hallucinogens.

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72 Comments »

  1. Jared Bond July 24, 2010 at 6:56 am - Reply

    How about “common” sense? A “sense of humor”? Haha j/k

  2. A M September 28, 2010 at 2:16 am - Reply

    “One experiment showed that, without consciously counting or anything of the like, a group of 19 to 24 year olds were able, on average, to tell when 3 minutes was up within a 3 second margin of error.”

    Actually, in this experiment, the participants were explicitly told to consciously count the seconds using a “1, 1000, 2, 1000, …” technique.

    Source: http://www.newscientist.com/article/mg15220571.700-why-time-flies-in-old-age.html

    • Daven Hiskey
      Daven Hiskey September 28, 2010 at 10:06 pm - Reply

      @ AM: Great find. Thanks for the comment.

  3. dan February 10, 2011 at 9:54 pm - Reply

    Pitch. Absolute or relative to some degree.

  4. emma August 5, 2011 at 3:46 pm - Reply

    Dear Author,

    This is a very informative article, although the last bullet has some information that is missing. In fact, synesthesia occurs naturally quite commonly, although it is also caused TEMPORARILY by hallucinogenic drugs. Synesthesia is a neurological condition in which the “wiring” for two or more senses are crossed in the brain. The most common forms are grapheme-color (letters and numbers have assigned colors)and sound-color (specific sounds have specific colors). The secondary sense (the one triggered by the primary sense modality) stays constant: if sugar smells purple, then it will always smell purple, and it will not change. Most synesthetes, because of their experiences, tend to be more creative, and often pursue artistic careers.

    No one knows for sure why synesthesia occurs, and no one knows solidly how much of the population is “afflicted” with this condition. It is normally estimated that one in every twenty people will have some form of synesthesia. Several theories exist to explain why synesthesia occurs, but none have been proven. Some say that everyone has synesthesia as infants, and as the synapses form, the wiring that connects all of the senses shrivel up and die. Synesthetes may be the result of when these wirings stay intact. Again, no one knows for sure, but this theory is the one most looked at for now.

    I know for a fact that synesthesia is hereditary, often passed down from parents to children, though it can skip generations, and this has been proven through studies of synesthetic families. I myself inherited this from my mother. However, it is rare that the offspring will share the same form(s) of synesthesia as the person they inherited it from. My mother has the rare mixing of all five senses, while I have all senses-color synesthesia.

    I hope you update this otherwise well-written article with this information. It will be of better use this way to suspected synesthetes and better educate the general public. Thank you for your time.

    -Emma

    • Shaun November 1, 2013 at 12:09 pm - Reply

      Good comment, Emma, and good article, David.
      I personally have always associated numbers with colours. Although this could be attributed to programming with Windows from a young age (which assigned common colours to numbers 0-15), the mapping is not identical. For example, the number 3 seems red to me, and the number 4 seems green.

      I have also experienced synesthesia at other times, both with and without the influence of hallucinogens.
      I have a theory, which, although it would not work for my number-colour thing, may yet be valid. Our brains measure a range of frequencies for each sense, and sometimes map a value from one range onto another. For example, a bass sound converts to red, as these are low-frequency (within the sensed range), and a high-pitched sound to blue, which is high frequency.

  5. John E. November 13, 2011 at 1:32 pm - Reply

    What allows humans to sense the distance of other things, an external proprioception?

    • Daven Hiskey
      Daven Hiskey November 13, 2011 at 6:56 pm - Reply

      @John: besides just through experience in terms of judging things size vs their apparent size due to how far they are away, your brain also uses the apparent difference in angle it’s observing between your two eyes to judge how far away it is (parallax). People who are blind or mostly blind in one eye don’t get this differential so they must judge primarily by experience. For daily life this isn’t too hard, once you’ve developed enough experience at it. I for one have been nearly blind in my left eye most of my life, though my right has exceptional vision (20/10). I have no problem with depth perception except in extreme cases like catching a pop up (baseball) coming down with a clear blue sky backdrop. In that situation, I’d say my depth perception is off by a good 20-30 feet, meaning I can tell within about that scale how far away it is, but beyond that it could be 5 feet away or 30, I can’t tell at all, making me a horrible outfielder ;-). If, however, there is a nice cloud cover as a reference point, I have non such issue and can catch it fine. Basically, as long as I have any sort of backdrop reference point for whatever, I can judge the depth fine, even for hitting a baseball, but otherwise not. Luckily, the world is full of backdrops. :-) In any event, for most people, parallax plays a large role in depth perception, which is why people who have good eye sight in both eyes often struggle initially with depth perception when they lose their sight in one eye. Obviously though when you see a truck 100 yards away, your brain doesn’t need parallax to tell about how far away it is, just because of its apparent size vs what your brain thinks the size of the particular model of truck should be.

  6. Anand April 7, 2012 at 12:47 am - Reply

    What about that sense of pain, when someone fall in love with someone.

  7. maxifer June 15, 2012 at 8:14 am - Reply

    It’s spelled “magnetoception” (or magnetoreception, if you must).

  8. Kevin Ross January 13, 2013 at 7:47 am - Reply

    Those of us who practice Tai Chi learn to sense Chi flowing through our body and how to control that flow. Which sense is being developed here?

    • Min June 17, 2013 at 6:58 pm - Reply

      The “chi” that practitioners of Tai Chi focus on isn’t really any kind of mystical energy. It’s thanks to a combination of proprioception, tension sensors, and equilibrioception that you can sense your muscles and joints move as you practice and concentrate.

  9. Atarii February 4, 2013 at 8:44 am - Reply

    Kevin Ross: “Chi” cannot be sensed, and does not actually exist, so it’s not a sense.

    • tala March 14, 2013 at 7:47 pm - Reply

      Atarii: Chi is just another word for bioelctricity. If there is a sense here it would be similar to feeling blood flow in your veins.

  10. alex March 27, 2013 at 3:22 am - Reply

    What about the sense of being filmed? being watched?

    • Rachylulu-poo August 1, 2013 at 3:37 am - Reply

      Cue chill down the spine!! Creepy!!!!!

  11. Arlene April 3, 2013 at 9:37 am - Reply

    Synesthesia can also be temporarily induced by some migraines, at least for some sufferers.

    What about the sense that an object is nearby; with someone’s eyes closed or for someone who is blind who can feel an object ahead of them before they run into it? Are they sensing air flow; a form of touch? Or something else?

    • Andrew April 26, 2013 at 8:18 am - Reply

      I think that would be a combination of senses…

      If you already knew where someone was when you closed your eyes, and then they moved you would hear them and know where they moved to.

      If someone sneaked up on you from behind, and you knew they were there, you would have either felt the air move when they approached and/or feel their body heat

      Or smell them

      Human bodies produce a weak electromagnetic field, if away from other sources of electromagnetism, the only magnetic fields to sense would be the planet’s, your own, and those of others. Since there’s no interference, it would be easier to sense the change in magnetic fields caused when a person moves

      But that’s just my hypothesis

  12. Bettina July 1, 2013 at 9:11 am - Reply

    Great page! How about a sense of daylight & the sun? And one of music? And sensing dryness in stale air?

    • Rachylulu-poo August 1, 2013 at 3:36 am - Reply

      I want all my senses to be of music!! I love music with most of my heart ( i have a life and family you know!)

  13. Rachylulu-poo August 1, 2013 at 3:34 am - Reply

    I love all this kind of stuff, but that doesn’t mean I can pronounce most of the words!!

  14. mansoor August 6, 2013 at 11:31 am - Reply

    Hi,
    What about laugher and sadness? Are they felt by any senses? Is there anything like sense of reasoning or intelligence? What about Sense of mind reading? I think these also to be identified as these also plays major roles in our day to day life.

  15. Yng August 21, 2013 at 10:36 am - Reply

    Nonsense (do not feel offended this comment is not specifically to U in person; much of this is humbug)
    Was Aristotle born before the Vedas
    Science always misleads and then defends itself by saying, ‘we r developing’.
    If U (the so called science) r in development stage, then why the hell r u trashing fully mature established science.

  16. Brianne September 13, 2013 at 8:17 am - Reply

    Neat! But it’s a “chimaera” fish, not a “chimeara”

  17. Kuya October 4, 2013 at 7:17 am - Reply

    Very educative document. Keep up

  18. Bill October 5, 2013 at 6:34 pm - Reply

    I can walk in my house and know whether or not my wife is present and, if so, in which room. She could even be sleeping and I would know that she was present. She rarely wears perfume or cologne, so it is unlikely that scent is cuing me in.

    This happens as soon as I enter, so I can’t identify any ‘ordinary’ clues that would provide this information.

  19. sarah October 17, 2013 at 9:38 pm - Reply

    is Echolocation? a sense

  20. rj October 19, 2013 at 9:43 pm - Reply

    I’m trying to keep an open mind, despite all the misspellings. It’s just so hard to take an article purporting “research” as credible when something as fundamental as “spelling” wasn’t important to the writer..

    • Daven Hiskey
      Daven Hiskey October 19, 2013 at 11:05 pm - Reply

      @rj: If you’d be so kind to note which words are misspelled that would be more helpful. Also, one’s ability to research has little to do with one’s ability to spell in one version of English or another. Don’t fall prey to the illogical notion that mastery of a particular language is indicative of intelligence.

  21. Shaun November 1, 2013 at 12:26 pm - Reply

    I’m sure of another sense that isn’t covered here, namely the ability to detect emotions. My theory is that emotions are expressed as vibrations in a person’s electromagnetic field (which surrounds them), and are sensed by those vibrations being transferred to water molecules in another person’s body. This would make sense for people near each other, although I’m aware that some people can sense emotions of people they are emotionally close to, even though they may be spatially distant.

  22. Derek December 9, 2013 at 6:59 pm - Reply

    What about depth perception?

  23. Shawn December 14, 2013 at 12:31 am - Reply

    I think I have senses that exceed normal humans. I can see things in others, my hearing is so good that it’s hard to hear people next to me cause of all the ruckess going on around. I heard a tick scream one time when I burned it. One day I was at work and I had this strong ringing in my ear that only came from a certain direction. I couldn’t fig out where it was coming from. I walked outside and could feel/hear the ringing/vibration and it was coming from the same direction from when I was inside. I can sense personalities, peoples moods, not sure how true this is but I think I can see good and bad in humans. Need a little guidance here lol

  24. Eric December 30, 2013 at 10:27 pm - Reply

    You used a term, “magentoception”, that is not correct. It should be “magnetoreception”.

  25. Solomon January 13, 2014 at 11:26 am - Reply

    Synesthesia is a lot more complicated than described here

  26. Josiah February 21, 2014 at 12:56 am - Reply

    There are many senses out there that the world doesn’t know about and isn’t ready for. There are sub senses of the basic 5, 6, 7 and 8. 6 being will or faith if you will, 7 being conscious thought and 8 being awareness.

  27. Bow March 1, 2014 at 7:27 pm - Reply

    Well common sense hasn’t prevailed here…i see people jump on the band wagon with your “spelling mistakes”, yet they lack the sense (common sense) to read all the comments before commenting as they want to show how “smart” they are with correcting you, yet if the had the sense and had taken the time, they would have seen that those issues (really irrelevant) have already been addressed.
    I personally found this article to be very interesting and was more interested in the content than the spelling of certain words.
    Thank you author!

  28. Alex March 24, 2014 at 11:35 am - Reply

    I found this very interesting. I have a couple theories from my own personal experiences in life. one is frequencies, I began to notice I would get a feeling of my phone ringing or my pocket vibrating BEFORE it would actually happen. later on Id have times where id think of a person and then my phone would go off, or id reach for my phone to call someone, (without touching or thinking about it (my phone) for a good amount of time) and it would ring almost instantly when I grabbed it. this is not a definite perfected sense, because other times I will be busy doing something and miss calls if my phone is on silent.

    Another sense I wonder about is not quite reading minds but I thought I heard somewhere that our brains produce short range frequencies. Sometimes I wonder if some people have the ability to not read minds, but moods or thoughts or direction of conversation. I think certain people give off bad vibes, and other people seem to talk about something I’m thinking about even if its something not normally on my mind, my theory is that our brains are subconsciously “getting in tune” with each others frequencies, and its just a feeling of “I was just thinking that” or “just about to say that” sry for the long run-on comment but this is all very interesting, I’d like to hear more on the topic if anything I’ve said is relevent

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