An Interresponse Time Analysis of Variable‐ratio Punishment

Abstract

An interresponse time analysis was used to study the effects of variable-ratio punishment schedules on the temporal pattern of reinforced responding. Twelve pigeons responded on a baseline variable-interval schedule of food reinforcement. A variable-ratio ten schedule of electric shock punishment was then introduced. The shock intensity was systematically increased to the highest intensity at which responding could be maintained. At this intensity, the mean variable-ratio value was increased and then decreased. Variable-ratio punishment resulted in an increased relative frequency of very short unreinforced interresponse times (response bursting). Increased response bursting accounted for instances of response rate facilitation. In addition, shock was followed by interresponse times of decreasing mean length over the first several responses after shock.

Suppressive and Facilitative Effects of Shock Intensity and Interresponse Times Followed by Shock

“…When absolute response rates are low, small increases or decreases translate into large differences in relative rates. Unlike previous research (e.g., Appel, 1968;Filby & Appel, 1966;Galbicka & Branch, 1981;Lande, 1981;Sizemore & Maxwell, 1985), shock intensity did not affect IRT distributions or response rates, and there was no interaction between shock intensity and the range of IRTs eligible for shock. This may be because the shock duration was too brief, the no-shock baseline strengthened responding, or shock intensity was manipulated across phases.…”

“…For example, Filby and Appel reported that 0.2‐mA and 0.4‐mA shocks increased response rates, but shock intensities of 0.6 mA and higher decreased response rates. Similar results were reported by Appel (1968), Arbuckle and Lattal (1992), Lande (1981), and Sizemore and Maxwell (1985).…”

“…Several studies have reported an effect of shock intensity. While some studies have reported response facilitation with low shock intensities (e.g., Appel, 1968;Filby & Appel, 1966;Lande, 1981;Sizemore & Maxwell, 1985) and response suppression with high ones (e.g., Azrin, 1956Azrin, , 1959Azrin, , 1960Azrin & Holz, 1961;Azrin, Holz, & Hake, 1963;Holz, Azrin, & Ulrich, 1963), others have reported response suppression across all intensities used, with high shock intensities suppressing response rates more than low shock intensities. These last studies include those by Filby and Appel (1966) and Hake, Azrin, and Oxford (1967) among others (e.g., Appel & Peterson, 1965;Azrin, 1959;Azrin & Holz, 1961;Azrin et al, 1963;Boroczi, Storms, & Broen, 1964;Sizemore & Maxwell, 1985).…”

“…Although adding a shock contingency often decreases response rates, it can also increase rates (Appel, 1968; Arbuckle & Lattal, 1992; Filby & Appel, 1966; Galbicka & Branch, 1981; Lande, 1981; Sizemore & Maxwell, 1985). This paradoxical effect has been observed with a variety of subjects (e.g., monkeys, rats, and pigeons), operants (e.g., lever presses and key pecks), and reinforcers (e.g., monkey chow, pellets, and access to grain).…”

“…Typically, response facilitation is more likely when the shock intensity is low (Appel, 1968; Arbuckle & Lattal, 1992; Filby & Appel, 1966; Lande, 1981; Sizemore & Maxwell, 1985). For example, Filby and Appel reported that 0.2‐mA and 0.4‐mA shocks increased response rates, but shock intensities of 0.6 mA and higher decreased response rates.…”