The life-cycle of the sea squirt is unique and instructive. As a free-swimming larva it has a three-hundred cell nervous system with sensors, a spinal cord, and an organ of balance which helps it find a suitable location for reproduction. Upon finding such a location, it lodges itself into the sand and proceeds to most of its nervous system. Apparently, the costs of maintaining expensive neurons only payoff when organisms are mobile. Two lessons can be gleaned from the life-cycle of this ancient organism; first, nervous systems co-evolved in response to the challenges posed by mobility, and second, cognition subserves action. Without the demands of dynamic – metazoan speed – activities such as exploration, evasion, predation, or construction, neuron based nervous systems have limited value. More generally, cognition and action are mutually reciprocating in a continuous loop. Cognition enables opportunities of action, which in turn feeds back to transform cognition.
These opportunities for action are exactly what the ecological psychologist James Gibson characterized by the concept of affordance. Affordances are relationships formed between a physical object and a cognizing agent. They signify opportunities and possibilities for action. For example, a spoon affords the possibility to feed oneself for humans, but not for a fish. A chair is a tool for resting for someone who is tired, but is a place to stand for someone trying to change a ceiling light, and an object to climb for a spider. Objects in the environment afford resources for exploitation, but the utilization of these resources are dependent on the sensorimotor capacities, homeostatic states, and the goals of the organism. As Gibson points out, an affordance is “neither an objective property or a subjective property…It is equally a fact of the environment and a fact of behavior. It is both physical and psychical, yet neither. An affordance points both ways, to the environment and to the observer.”
The Bible stated that “in the beginning was the word,” but Goethe recognizing the primacy of action, altered it to “in the beginning was the deed.” Actions are the drivers of cognition, mobility was the catalyst for the evolution of a nervous system. Affordances – opportunities for action – are born from the interaction of the organism with the environment. For humans, these affordances arise predominantly from our interactions with our designed material artifacts – our technologies. The failures (and successes) of our actions can in large part be attributed to the failures (and successes) of this relationship between artifacts and minds. In my next set of essay(s), I would like to examine this relationship specifically for the emergency department (ED) .
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[…] Building on these foundations, the physical exam has progressively expanded in scope and increased in refinement. It now consists of the vital signs – respiratory rate, temperature, blood pressure, pulse oximetry, and heart rate – and a systems based head-to-toe exam designed to elicit signs of disease. Technologies such as the thermometer, the sphygmomanometer, and the pulse oximeter have made the measurement of vitals signs more accurate and easier. The stethoscope – invented in 1816 – extended perception, so physicians could listen to heart and lung sounds. Over time, other sensory modalities were trained to recognize patterns that correlated to specific diseases. In effect, expanding the set of affordances. […]
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