A hierarchical response-unit analysis of resistance to extinction following fixed-number and fixed-consecutive-number reinforcement

Exp I (24 male Holtzman rats) measured tray approaches in extinction as a function of acquisition response requirement after training on fixed-number (FN) schedules. The predicted independence of unit length and number was observed following discrete-trials training. After free-operant training, total units to extinction increased with FN requirement. A hierarchical response-unit hypothesis argues that omission of reward following sub-requirement tray approaches leads to integration of single (1st-order) units into functional responses consisting of several 1st-order units (a 2nd-order unit). Exps II and III (48 female hooded and 36 male albino rats, respectively) supported the hierarchical response-unit hypothesis in that length and number of 1st-order units in extinction were independent functions of acquisition response requirement and 2nd-order unit size, respectively. (11 ref)