Shock-induced threat and biting by the turtle.

Shock-induced biting and threat by the male painted turtle (Chrysemys picta marginata) were studied in three experiments. When restrained facing each other, the turtles threatened and bit other turtles in response to electric shock. Shock alone caused turtles to threaten an unshocked turtle; the movements of a shocked turtle were sufficient to cause an unshocked but restrained turtle to threaten. When the turtles were free to move, they avoided an encounter when shocked, even reversing a strong position preference in order to do so.