The Grey Walter Picture Archive

	This annotated photograph from 1950 shows Elsie with her shell off and all the parts labelled.
	This photograph is the first of 9 taken at a single session in Grey Walter's house in 1950. Candles were fixed to the turtles' shells, and long exposures were used. The light streaks show the paths of the turtles. These are the best scientific records we have of the way the turtles actually behaved. This photograph shows Elsie approaching a light, and then circling around it at a distance.
	Elsie moves into the hutch, attracted by the light.
	At first Elsie cannot see the light, which is hidden by the screen, and so she searches for light with her characteristic oscillating movement. She collides with the screen, and when she recoils from the screen the light comes into view. She approaches the light and circles it at a distance.
	This time Elsie successfully avoids a stool and approaches the light.
	This shows Elmer and Elsie interacting. At first they move towards each other, and engage in the fascinating dance described in "The Living Brain". However when the light in the hutch is switched on, they ignore each other and both head for the hutch. Elsie always worked rather better than Elmer so she gets there first. Note Elmer's shell, fabricated from many separate pieces of material.
	Elsie moves into the hutch again, this time from the right hand side.
	This shows a behaviour that Grey Walter regarded as being of great importance. At first, Elsie approaches the upper light, and begins to circle it. However, when she catches sight of the second light, she moves towards it and begins to circle it. Grey Walter claimed that this showed the ability to choose between alternatives.
	Elsie enters the lighted hutch again. The thin swirling light trails near the candle track show the movements of Elsie's pilot light. The pilot lights were originally installed to indicate that the steering mechanism was in operation, but they also provided the basis of the 'social interaction' between turtles.
	Elsie performs the famous mirror dance.
	Elsie enters the hutch. Note the battery charger at the back of the hutch; Grey Walter fixed the charger terminals to contacts on the hutch floor, enabling the turtles to recharge automatically when they entered the hutch.
	This is the original circuit diagram for the 1951 turtles. It is slightly different from the circuit diagram for Elmer and Elsie, but works in the same way.

Acknowledgements: The Burden Neurological Institute, for their assistance with this project, and for their kind permission to use these archive pictures. All pictures above are copyright Ó Burden Neurological Institute.

Researcher and editor: Owen Holland
Please address questions to: Alan Winfield