Sense and Perspective — Part 1
Perception Comprises Much of Human Experience Yet Remains A Difficult Frontier for the Sciences
Does red have the same hue inside everyones mind’s eye?
Science gives clues but the age-old question enters the realm of philosophy from a certain angle. Due to limitations of the scientific method concerning experience and consciousness (discussed a bit previously here) a definitive answer seems elusive if not impossible to prove scientifically. Blindness and colorblindness exist, so on that level, the answer is no. But on another, the scientific method is simply ill-equipped to examine these experiential questions. As far as science has proven, one cannot experience or measure another’s consciousness or memory, making scientific study of senses difficult. Spectrums of experience must be translated into finite language or action by us fickle, distractible beasts relying on imperfect senses filtered through layers of mental processes colored by emotion until only some of the signal reaches consciousness. And . . . we don’t really know where that consciousness comes from or how it works.
A breakthrough (maybe in mind-machine interface) is required to reliably answer such questions. Until then, knocking around some observations in other realms of sensory experience might help shed light on these frontiers.
Do sensory differences impact how individuals think and see the world? What are the implications?
More Sense Than We Realized
Common framing of ‘the 5 senses’ to describe human sensory experience is outdated and wrong. Eighties-era elementary school textbooks at least (dating myself) didn’t mention several internal senses recognized today. These include sense of movement (proprioception), sense of balance (equilibrioception) and sense of internal body state (interoception). Different hardware powers each. Proprioception involves nerves throughout muscles. Balance perception centers on the inner ear. Interoception, complex and enigmatic, relies on a huge variety of receptors throughout organs (more on this below.)
Even within ‘the 5 senses’ from grade school, important new understanding has emerged since. The savory taste sensation, umami, was discovered in Japan in 1908, but not accepted in Western science for about 100 years (because racism basically.) And published just this month, USC researchers found ammonium taste ability, some claiming it a 6th basic taste. Supposedly, it tastes like salty licorice, an adaption to detect rotting meat and fish. More results will be needed to confirm this 6th taste sensation exists independent from the others.
Existence of other human senses is more controversial. Magnetoreception, the ability to sense electro-magnetic fields is firmly established in migratory birds, electric eels and other animals. Birds evolved magentoreception machinery to aid sense of direction and navigation, mediated by a blue-light-triggered mechanism within the eye. So, these birds “see” Earth’s magnetic fields. Meanwhile, dogs, when pooping, tend to align themselves with north-south geo-magnetic lines, for some strange reason.
Convincing new data show humans have magentoreception also, published in Nature in 2022. The researchers observed this effect only in men, weakly, and improved when direction was associated with food, as would be the case when hunting and gathering.
Replication of these results will be required to win over a scientific consensus. Even so, this discovery made so recently demonstrates weakness in our current scientific understanding concerning human senses and mental ability. Measuring small experiential sensory signals on the cusp of consciousness remains difficult.
What else are we missing?
Mind-Body Impulses and the Unconscious
Interoception remains mysterious but central to human experience and function. It accounts for many sensations that indicate internal states, comprising much of our sense of well-being. All this is strongly associated with mood, which in turn influences other perceptions, and also often preferences too. In other words, this weird internal sense affects mood and, in turn, how we sense everything else, and even affects the things we like and dislike, and so are inclined to do and not do.
So why haven’t we learned more about how this stuff works?!
Interoception includes familiar visceral sensations from empty-stomach to heart-beating to need-to-poop. But also, this system uses an array of internal chemical sensors most hardly ever notice. Blood-oxygen and intestinal sensors, for example, enable the nervous system to coordinate circulation and digestion. Normally, this doesn’t require conscious bandwidth. Instead, an unconscious executive center, strange as it may seem, handles most routine interoception signals. The conscious mind is only alerted as necessary, the signals otherwise are blocked or repressed. Weird — our unconscious mind (which I’ll refer to as the shadow) mostly call the shots here.
In critical situations, like when starved of oxygen, interoception signals register consciously and even overwhelm other mental activity. Here the shadow whips the conscious self into action to restore function. For example, a free-diver becomes conscious of low blood oxygen, an impulse to return to the surface for air. If ignored, the signal strengthens becoming urgent and imperative.
In other situations, oppositely, signals that normally register to the conscious mind are delayed or repressed. For example, adrenalized soldiers wounded on the battlefield often don’t register pain until reaching safety. Here the shadow calculates intense pain would impede survival in the face of immediate danger and so it blocks the sensation. This represents a beneficial cognitive adaption promoting survival — a healthy shadow.
But when interoception goes wrong, needless suffering follows. By definition, interoception comprises the sensory portion of the mind-body connection, often overlooked in modern medicine. A mountain of psychological and psychosomatic disorders are related to this sense included anxiety, insomnia, substance addiction, PTSD, anorexia, irritable bowel syndrome, obesity, various sexual dysfunctions and OCD among others. Fundamentally, all involve interoception signals getting messed up or misinterpreted. Bad shadow!
Because interoception is mostly unconscious, correcting or even sometimes self-identifying these conditions can be quite tricky. Ask any addict.
These dynamics, again, make scientific research of all this fundamentally fraught and difficult. How can one repeatably study a signal being manipulated willy-nilly by this strange shadow? It is no wonder modern medicine and psychology struggle to effectively treat these conditions.
Many normal mental complexes also connect to this weird sense, in turn affecting behaviors and preferences. For example, sense of disgust revolves around internal signals to do with nausea and hunger, deeply coloring one’s experience of the world. Likewise, sex drive hinges on healthy body signals as well as external stimulus, and in turn dramatically increases appetite for risk-taking among other behaviors. Pain, too, profoundly impacts human perspective and mood. Ask any artist.
You Down With ESP?
Extra-sensory perception (ESP) is not accepted by the scientific community. However, a surprisingly large body of psychological research suggests the scientific community may be missing something.
Dozens of ‘Ganzfeld’ experiments have for decades tested whether isolated individuals can receive information from other isolated individuals. Strangely, the bulk of such studies detect small but significant effects, on average ~10% more hits than would be expected randomly. Improved study designs better isolating participants and mediated by computers have more recently produced similar but smaller effects. These results have been challenged as stemming from leaky study designs, dismissed by a consensus of scientists. Extraordinary claims require extraordinary evidence after all.
A decade-old body of research provides more sturdy evidence for precognition, that people can somehow sense into the future. Published in the mainstream Journal of Personality and Social Psychology, in an array of experiments, Cornell psychologist Daryl Bem found surprisingly strong evidence for precognition. In one, a 6% increase in hit rate was observed predicting where an image would be displayed, behind curtain #1 or #2, decided after the selection by computer randomization. Interestingly, the effect was only present with porno pics (with 99% confidence), but not more mundane ones. Another trial found after-the-fact repetition of a memory-recall task improved earlier performance. That is, the benefit from practicing somehow went backwards in time. All in all, over the 9 experiments the average effect was small but from impressively rigorous study, using standard methods and reaching 95% confidence in 8 and 99% in 4 of the 9 experiments.
…memory works both ways…
The White Queen, from Lewis Carroll’s Through the Looking Glass
Bem challenged skeptics and sympathizers alike to replicate his results, offering research packages to assist. While many did not see the effect, most did. Bem compiled all who participated in a 2015 meta-analysis including 90 study reps from 33 separate labs. Taken together, results matched the earlier-observed effect but now with astounding statistical confidence. Bem claims these highly significant results bested 6-sigma, greater than the 5-sigma standard in particle physics. All in all, Bem claimed confidence of 99.99999999%
Some skeptics claim Bem’s statistical techniques are flawed. Others argue modern psychological research methods are invalid. Indeed, this work helped ignite a crisis of reproducibility within psychological research still playing out today. A research campaign born out of this crisis only was able to replicate less than half original findings from reputable psychology journals. Sheesh. But meanwhile, Bem’s results were replicated to startling significance, or at least so says his 2015 meta-analysis. But not in a large 2023 study, which sought to test Bem’s results with improved methods and found no precognition.
Much more evidence would be needed to establish existence of extra senses and especially woo woo ones. Still, this body of observations, of which the above only scratches the surface, shouldn’t be ignored either. Perhaps current understanding is missing something important in this difficult-to-study realm. This being an active research topic in 2023, attracting Ivy League research in prominent journals again illustrates, if nothing else, how difficult it is to study weak sensory phenomena scientifically.
Supertasters and Sensory Superiority
Less controversial, but still weird, individuals have enormous differences in bitterness sense. More than simply a difference in sensitivity, some people taste bitter substances others can’t detect at all.
Some ~25% of people cannot taste a group of bitter chemicals like 6-n-propylthiouracil aka PROP, and researchers dubbed these non-tasters. Another ~25%, supertasters, are extremely sensitive to PROP. Everyone else, medium tasters, can detect it, but only a lil’ bit.
Sensory scientists have linked these groupings to genetic factors which encode a specialized bitter receptor in taste buds and also determine the number of taste buds present on the tongue — supertasters have far more than nontasters. It turns out supertasters also have heightened perception of other tastes and even odors too.
So supertasters, sporting an evolutionary advantage, are superior sensory overlords?
Not so fast. Would you want more of an unpleasant sensation? Researchers have associated supertasters with picky eaters and more limited diets. This group tends to have heightened negative emotional responses and to enjoy food less. Hate broccoli? Aversion to bitter foods like broccoli, hoppy beers and dark chocolate link to supertasters.
Bitterness sense is thought to have evolved to help avoid poisonous foods. While super-tasting offers this advantage in the wild, it seems less important to modern lifestyles where food is relatively safe and abundant. More relevant, supertasters have lower obesity rates. It seems human evolution settled on this diversity in bitter tasting because important tradeoffs are involved.
Enormous differences in sensory hardware, ability and sensitivity exist normally, not just due to disability. These differences inform likes and dislikes, and in turn, behaviors.
So, while a red apple maybe appears the same hue to all, a red apple definitely doesn’t taste the same to all. And this accounts for much of the reason why some people like apples — and so eat apples — more than others.
Thanks for reading! Check out Part 2 here…
