Transituational Immunization Against the Interference Effect (Learned Helplessness) by Prior Passive and Active Escape

Abstract

Rats were taught to escape shock by either a relatively active jump-up response or by a relatively passive crouching-freezing response. One half of each group then received inescapable tail shocks in a restraining tube while the other half were restrained without shock. Control groups received either inescapable shock or restraint without prior escape training. An additional control group remained in its home cage throughout these procedures. All rats were then taught to escape shock in a shuttlebox by completing two crossings per trial (fixed ratio two) for 25 trials. Compared with the untreated controls, the group receiving inescapable shock alone showed learned helplessness. Both passive and active escape training immunized against learned helplessness, with passive escape training being the most effective. Restraint alone also produced some interference with shuttle escape, unaffected by immunization pretreatments. Activity measures during inescapable shock showed that passive escape trained rats were most active, while active escape trained and control rats showed the same lower level of activity.