Phenology
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Our perception of the world around us is influenced, to varying degrees, by the sensory information we receive about it.
In some cases, this relationship is fairly straightforward and obvious: we experience fear when our eyes or ears or nose transmit information that implies a bear or other predator might be nearby, stalking us, and we may experience pleasure and/or hunger when we smell the telltale fragrance of fresh-baked cinnamon rolls.
Both sets of environmental data are sent to our brain and processed, and other information is thenceforth filtered accordingly: we perceive subsequent events through the lens of there maybe being a bear nearby, or the hopeful potential of the near-future acquisition and consumption of a delicious pastry.
There are other signals of which we tend to be less conscious, though, that also inform our perception. And some of these signals originate within the body, rather than without.
The heart, in particular, seems to significantly influence our physiological and psychological response mechanisms, according to research that began in the 1930s and which continues today.
Our heartbeat cycle can be divided into two phases: the systole, during which the heart contracts and pumps out blood, and the diastole, when the heart relaxes and refills with blood.
According to a study published in 2013, people are more likely to forget words to which they were exposed during the systole portion of the heartbeat cycle.
Another study, published in 2020, shows that subjects were more likely to perceive a slight electrical stimulus in their finger when it was applied during the diastolic portion of their heartbeat than the systole. This cyclical system, then, despite being quite rapid, seems to change how we respond to stimuli, from half-heartbeat to half-heartbeat.
Interestingly, a 2014 study showed that, even though some other responses were inhibited during the systole portion of the heartbeat, fear, and the general processing of threatening stimuli, is not. In fact, the amygdala is activated during this brief moment, which can cause people to perceive fear in other peoples’ faces more intensely than they otherwise would.
Some researchers believe that this might be an adaptive response to danger: if you’re running from a predator, your heartbeat flutters faster, and you become less sensitive to pain and more aware of potential threats—a serious advantage if you’re trying to get away from something that wants to kill and maybe eat you.
Current research into this subject has found evidence that this same heartbeat-related awareness cycle seems to be tied to our creation of memories and reflexive responses related to danger and fear. It’s been shown that our active sampling of the environment—our eyes moving very quickly, subconsciously scanning our environment for data—is also tied to the systolic half of the heartbeat cycle, while we tend to fix our gaze on specific targets of interest during the diastole. The implication of which seems to be that in the space of a heartbeat, we have a period in which we collect information about the world around us, followed by a period in which we process that data.
We have a similar sensitivity to rhythms and cycles that occur outside our bodies.
Day-night cycles, seasonal changes in our environment, the change in environmental sounds, adjustments in temperature, in weather, the types of pests that invade our space or the types of food that become available based on agricultural rhythms, but also economic ones.
The broad term for this type of external cycle-sensitivity is “phenology” (not to be confused with the debunked pseudoscience of “phrenology”) and it applies to most, perhaps all types of life, not just humans.
Even small variations in a seemingly inconsequential aspect of the environment can have a dramatic impact on an entire species, like honeybees or ferns or human beings. And these changes in how we respond to our environments can cascade into larger changes because other life adjusts as we adjust, and vice versa.
There’s an elegance to this concept, as it scales up to the size of an entire planetary ecosystem, with all the interconnected pieces functioning in relation to all the other pieces.
This concept also scales down to the size of a single organism—or individual super-organism, as is arguably case with humans. We’re each made up of many different types of life, our internal rhythms moderating and moderated by countless processes happening around and within us, those systems influencing how we perceive the world, and those perceptions, in turn, shaping how we behave.
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