In marked contrast to Martin's examples, the learners I worked with
immediately embraced negative feedback systems as a natural way to
implement control systems. This suggests to me that because of their
visual impairment, negative feedback systems became part of their
everyday lives. The routine of performing some act, expecting tactile
feedback, and performing it again is precisely this idea. A concrete
example of this can be found in their use of the cane. As a visually
impaired person sweeps a cane back and forth, their arc and position
changes based on what they find. If they encounter some object, their
gait and sweep changes to discover the range of the obstacle, and adjustments
are made to bypass it. This is a negative feedback control system,
but the key difference is that they are part of it - using some device to
sense, and then acting on that data to correct for some goal. This close
relationship to the concept leads me to propose that the idea of negative
feedback is more likely to be developed in visually impaired learners. It
also presents another model of introducing sighted students to the idea
of feedback - one that places them in the control loop by replacing one
of their senses with an electronic sensor.