Oscillatory behavior during approach-avoidance conflict.

During one stimulus, food rewards and electric shocks were intermittently delivered to rats regardless of their behavior. Subjects could either terminate or initiate this stimulus by pressing a lever. Effects of the relative frequency of food and shock were studied by manipulating the variable-interval schedules associated with each. Increases in the relative frequency of shocks led to decreases in the amount of time each rat spent in the stimulus. Subjects initiated and terminated the stimulus most often at intermediate relative frequencies of food and shock, rather than in situations where the conditions were either very favorable (e.g., only food was possible) or very unfavorable (e.g., only shock was possible). This technique thus provides quantitative data on oscillatory behavior during conflict which confirm and extend results previously obtained by qualitative observation.