Partial control and learned helplessness in rats: Control over shock intensity prevents interference with subsequent escape

Abstract

The effect upon subsequent escape acquisition of control over shock intensity in the absence of control over other shock characteristics was examined. Pretreatment involved random shocks of 1.6 and .75 mA at a density of about 10/min. The experimental group could avoid the higher shock intensity if they leverpressed at least once every 15 sec. Yoked and no-shock rats completed the triadic design. Experimental and yoked animals received all scheduled shocks. Triads were later tested for FR 2 shuttlebox escape at either the .75 mA (low) or 1.6 mA (high) intensity. During testing, avoidance rats performed as well as no-shock rats at the low intensity and escaped even more rapidly at the high intensity. Yoked rats showed interference at both intensities, with interference very marked, including many failures to escape, at the low intensity. These findings indicate that control over shock intensity, by itself, is sufficient to prevent learned helplessness and suggest that control over any salient characteristic of shock may be sufficient for immunization. © 1979 Psychonomic Society, Inc.