Is bar-holding with negative reinforcement preparatory or perseverative

Avoidance Behavior in a Bar-Pressing Situation as a Function of Release Shock Intervals

4 white rats were given training in avoiding shocks by pressing a bar. Shocks were scheduled to occur after different release-signal (S1) and S1-shock intervals. When these intervals totalled 125 sec. no bar-holding occurred; when they totalled 20 sec. bar-holding was almost continuous; when they totalled 60 sec. intermediate amounts of bar-holding were emitted by 3 animals. Once acquired, bar-holding was maintained according to the interval from bar-release to impending shock; circumstances of its acquisition were obscured by qualitative characteristics of response topography.

A comparison of forward and backward procedures for the acquisition of response chains in humans

Ten university students each learned four separate six-link response chains, two forward and two backward. All 10 subjects made fewer errors in the forward procedure. It was concluded that the forward procedure is superior because each link of the response chain is acquired by direct reinforcement.

Escape, avoidance, punishment: where do we stand?

This paper reviews progress since the author's previous writings in three areas. In escape training, the preparatory-response explanation of bar holding still appears to be valid. In avoidance, the newer safety-signal version of two-factor theory has much to recommend it and readily incorporates Anger's conditioned aversive temporal stimuli formulation. Shock-density reduction is rejected as a substitute for two-factor theory. Finally, criticisms of the avoidance interpretation of punishment are answered and recent empirical data are cited in its support.

2-Deoxy-D-glucose-induced decrements in operant and reflex pain thresholds

Acute exposure to many environmental stressors induces significant analgesia. The present study examined whether 2-deoxy-D-glucose (2-DG), an antimetabolic glucose analogue, which induces glucoprivation and peripheral sympatho-adrenal discharge, would also produce analgesia as measured by either an operant liminal escape or a reflex tail-pinch procedure. In the liminal escape paradigm, 9 rats were tested at weekly intervals in 6 randomly selected testing conditions: 30 min pre-test injections of four 2-DG doses (100, 225, 350 and 700 mg/kg, IP) and 180 min pre-test injections of the 2 higher doses. Moderate analgesia occurred at the lower 2-DG doses 30 min after injection, while profound analgesia occurred at the higher doses. After 180 min, only the 700 mg/kg 2-DG dose produced moderate analgesia, which was further enhanced by food deprivation. Rats tested in the tail-pinch paradigm displayed a similar dose-dependent analgesia course. These results demonstrate that 2-DG decreases nociceptive sensitivity, possibly through stress-induced activation of an intrinsic pain-inhibitory system.

The elimination of interfering response patterns in lever-press avoidance situations

Lever holding into shock and short-latency responses to shock onset are two response patterns that interfere with avoidance acquisition in free-operant and discriminated avoidance situations. In an attempt to eliminate these patterns, an additional timer disabled the lever for a period slightly longer than shock duration. A free-operant avoidance schedule with a warning stimulus, but without the additional timer, constituted the control condition. The lever-disabling timer was turned on by different events in two experimental conditions: (a) release of the lever at the onset of shock, (b) shock onset. Interfering responses diminished most rapidly, and efficient avoidance behavior appeared earliest, when the lever-disabling timer was turned on by shock onset.

Double discrimination avoidance with a single stimulus

Four white rats were trained to avoid electric shocks by depressing a bar after the onset of a stimulus and releasing it after termination of the stimulus. All subjects acquired the behavior of holding the bar in the presence of the stimulus and releasing it in the absence of the stimulus, but one animal almost always required a "priming" shock. The others exhibited a high level of shock avoidance.