Escape and avoidance learning in the earthworm eisenia hortensis

Abstract

Interest in instrumental learning in earthworms dates back to 1912 when Yerkes concluded that they can learn a spatial discrimination in a T-maze. Rosenkoetter and Boice determined in the 1970s that the "learning" that Yerkes observed was probably chemotaxis and not learning at all.We examined a different form of in-strumental learning: the ability to learn both to escape and to avoid an aversive stim-ulus. Freely moving "master" worms could turn off an aversive white light by in-creasing their movement; the behavior of yoked controls had no effect on the light. We demonstrate that in as few as 12 trials the behavior of the master worms comes under the control of this contingency. © 2014 Wilson et al.