Hack 62. The Broken Escalator Phenomenon: When Autopilot Takes Over (3)
The first time the subjects stepped onto the moving walkway, they lost their balance and grasped the handrail. But over the next few attempts, they learned to anticipate the unbalancing effect of the walkway by speeding up their stride and leaning their body forward.
Then crucially, when the volunteers first walked onto the walkway when it was switched off, they continued to walk at the increased speed and also continued to sway the trunk of their body forward. They performed these inappropriate adjustments even though they could see the walkway was no longer moving and even though they had been told it would no longer move. However, this happened only once. Their brain had apparently realized the mistake and the next time they walked onto the stationary walkway they didn’t perform these inappropriate adjustments. Consistent with anecdotal evidence for the broken escalator phenomenon, most of the volunteers expressed spontaneous surprise at the sensations they experienced when they first stepped onto the stationary walkway.
6.2.3. In Real Life
There are obviously differences between the lab experiment and the real-life phenomenon. Our brains have learned to cope with escalators over years of experience, whereas the experimental volunteers adapted to the lab walkway in just a few minutes. But what the real-life phenomenon and lab experiment both represent is an example of dissociation between our conscious knowledge and our brain’s control of our actions. The volunteers knew the walkway was motionless, but because it had been moving previously, the brain put anticipatory adjustments in place anyway to prevent loss of balance. Usually these kinds of dissociations work the other way around. Often our conscious perception can be tricked by sensory illusions, but the action systems of our brain are not fooled and act appropriately. For example, visual illusions of size can lead us to perceptually misjudge the size of an object, yet our fingertip grasp will be appropriate to the object’s true size. The motor system gets it right when our conscious perception is fooled by the illusion size (see [Hack #66] to see this in action).
These observations undermine our sense of a unified self: it seems our consciousness and the movement control parts of our brain can have two different takes on the world at the same time. This happens because, in our fast-paced world of infinite information and possibility, our brain must prioritize both what sensory information reaches consciousness and what aspects of movement our consciousness controls. Imagine how sluggish you would be if you had to think in detail about every movement you made. Indeed, most of the time autopilot improves performancethink of how fluent you’ve become at the boring drive home from work or the benefits of touch-typing. It’s just that, in the case of the broken escalator, your brain should really have handed the reins back to “you.”
6.2.4. End Notes
Reynolds, R. F., & Bronstein, A. M. (2003). The broken escalator phenomenon. aftereffect of walking onto a moving platform. Experimental Brain Research, 151, 301-308.
Reynolds, R. F., & Bronstein, A. M. (2004). The moving platform aftereffect: Limited generalization of a locomotor adaptation. Journal of Neurophysiology, 91, 92-100.
Christian Jarrett
Taken from : Mind Hacks
