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

3. 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

4. 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.

5. 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

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

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

8. 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.

9. 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

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

11. Energetics in Walk-Run transitions  Here’s 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?

12. 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

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

14. 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.