International Journal of Comparative Psychology

Because woodlice ( Porcellio scaber and pillbugs ( Eluma purpurascens ) that traveled closer to the outer wall of alleys both before as well as after a 90° forced turn subsequently made sharper free turns in the opposite direction, it seemed possible that a quantitative relationship existed between tactile stimulation arising from wall contact and free-turn behavior However, on emerging from straight runways, without any forced turns, pillbugs turned at sharper angles than woodlice but there was no relationship between the size of a turn and amount of wall contact apart from a very minor one for woodlice only. It was concluded that tactile stimuh played a negligible part in turn alternation of either species thereby supporting involvement of proprioceptive cues. By requiring woodlice to negotiate a forced turn lined with glass on the outer half of the floor, it became apparent that their alternation was determined by proprioceptive feedback from bilaterally asymmetrical leg movements rather than distortion of body segments.