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CHAPTER 5, SLIDE SET 5 Supplement: Hysteresis, perception-action coupling, more walk-run data, energetics

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Hysteresis 12 3 54 Listen to this first! Then proceed with the others, going from 1 to 5 http://perso.wanadoo.fr/l.d.v.dujardin/ct/cusp.html#applet2

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Hysteresis Walk Run Speed (control parameter) Order parameters The difference in the speed (at which the person is running/walking) when the transition is made from walking to running, compared to when the switch is made from running to walking, signifies the presence of hysteresis further definition in audio 1. 2.

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Perception-action coupling The swinging room (Lee & Aronson, 74) The swinging room was (is?) a box hanging from the ceiling of a large hall Participant stands in center of fake room, looking at front wall (field of view filled with fake room) Experimenter (Lee) stands behind fake room, holding a rod connecting the back walls, so that he can swing the room back and forth an inch or 2

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Perception-action coupling The swinging room (Lee & Aronson, 74) Direction of motion of swinging room

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Perception-action coupling So which way would you sway (relative to the room)? Direction of motion of swinging room ?

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Perception-action coupling Other applications of (tau - time to contact - used to guide movement) Echolocation in bats Diving gannets Driving, feeding (hand to mouth), kicking, running, steering, catching, etc., etc., etc.

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Shapiro et al.s data (1981) Note the change in proportion of time spent in phases of step cycle as speed increases... A change in a control parameter drives a change in an order parameter

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Energetics in Walk-Run transitions There have been many research investigations into the kinds of things I discuss here. Heres another few excerpts... First bit discusses hysteresis

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Energetics in Walk-Run transitions Heres a summary of data... They did roughly the same thing as Shapiro, but also reduced speed Note that hysteresis appears as predicted. But why? What are the causes of the transition?

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Energetics in Walk-Run transitions A quick review of why we might expect such transitions... Open systems use energy as the basis for behavioral self- organization

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Energetics in Walk-Run transitions When you look at the energy expended by different ways of moving, it seems to explain things...

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Energetics in Walk-Run transitions Some more data from same experiment as before... Totally fits the theoretical picture that has energy cost at the top of the tree, leading the system to complex adaptations in gait.