A comparison of leverpress and head-poke discriminated Sidman avoidance

A discriminated Sidman avoidance procedure used by Forgione (1970) was replicated using a head-poke response instead of a leverpress as the avoidance operant. The resultant data were described in terms of the five dependent measures reported by Forgione. Head-poke avoidance was found to be more efficient than its leverpress counterpart and compared very favorably with the lever-disabling (or shock-timer-on) procedure used by Forgione to break up inefficient leverpress behavior patterns.     

A technique for rapid,reliable assessment of thermal-pain threshold in humans

A simple and reliable method of assessing pain threshold in humans may be useful in a number of research areas, such as in examining acute antinociceptive effects of drugs. We have developed a low-cost, computer-controlled method to reliably assess thermal-pain threshold using radiant heat focused from a slide projector and applied to a small area of skin. An electronic shutter is attached to the projector opening to provide precise onset and offset of heat. A computer keypad allows for subject response at the point of pain onset (i.e., threshold), with latency to threshold determined by computer timer. The details of the apparatus setup, subject preparation, and instructions to subjects are presented. The development of the method is described, and sources of unreliability are identified. Coefficients of variation (CVs) are calculated to provide a measure of variability within subjects across trial exposures and across sessions. Results indicate that the method is reliable for determining pain threshold, especially within sessions, and can be employed with relatively minimal expense and subject preparation.     

"Warmup" and "cooldown" in Sidman avoidance behavior of rats: A dual-process interpretation

The present experiment investigated relations between "warmup" in unsignalled Sidman avoidance in rats and the intensity of shock. Magnitude of shock-rate change was quantified by comparing the rat's behavior during the initial third and the final two thirds of the same session. Warmup was said to occur whenever the shock rate during the initial 20 min was higher than the shock rate during the final 40 min of a 60 min session. "Cooldown" was defined as lower shock rate during the initial 20 min than during the final 40 min. Warmup was observed when shocks were intense, cooldown was observed when shocks were low intensity, and neither was observed when medium-intensity shocks were administered. Response-rate changes were correlated with shock-rate changes, but were smaller. The results are interpreted within the framework of a dual-process theory of habituation.     

A technique for producing highly complex visual stimuli

The production of randomly generated polygons of high complexity is a very time-consuming process with presently available methods. A technique was developed for speeding this process, particularly when producing very complex figures (e.g., polygons with over 40 sides). A portion of this process was computerized to facilitate production further. The procedure was employed to produce polygons with up to 200 sides. The technique proved feasible in practice, and subsequently clear results were obtained with the polygons in research on visual exploratory behavior.     

An efficient one- and two-way avoidance apparatus capable of producing identical one- and two-way avoidance performance

A platformed one- and two-way avoidance apparatus is described in which the need for handling the subjects in the one-way task is eliminated and the two-way task is very quickly learned. The acquisition curves obtained for these two tasks are indistinguishable.     

A rapid technique for visualizing cerebral arteries in rat.

Intracardiac perfusion with cresyl violet acetate dissolved in 0.9% isotonic saline and dimethyl sulfoxide (DMSO) allows one to visualize the arterial blood supply to the central hemispheres. This technique is especially useful in demonstrating the ramifications of and areas supplied by the middle cerebral artery. Many individual differences in the course traversed by the artery and the distal areas supplied were observed. This technique could prove to be a useful adjunct to neurohistological techniques in studies investigating rodent models of stroke.     

A rapid automatic technique for generating operant key-press behavior in rats

Experimentally naive rats were trained to key press on a fixed-ratio 10 schedule of food reinforcement by a completely automatic procedure within a single, 1-hr session. Control procedures demonstrated that the resulting behavior was an operant, under control of the schedule of reinforcement and the specified reinforcing stimulus (food). A simple, combination food-tray operandum, also described, was used as the basis for the training technique.     

Some factors involved in the comparison of response systems: acquisition, extinction, and transfer of head-poke and lever-press Sidman avoidance

Head poking, a suggested natural escape reaction to shock for the rat, was compared to lever pressing in a Sidman avoidance study. Both responses could be emitted at any time, but only one was effective in a given session. Acquisition and extinction of the two responses were compared under both signalled and unsignalled avoidance. Then, a test for transfer was conducted in which acquisition conditions were re-instated, but the effectiveness of the responses was reversed. Three differences between responses were noted: (a) head poking was superior in reducing shock rates under signalled conditions; (b) head poking was more resistant to extinction, especially under signalled conditions; (c) under unsignalled conditions, animals were unable to learn to head poke if they had previously learned to lever press. Findings a and c were pursued in later experiments. Finding a depended on the location of the warning signal with respect to the response system. When the lever press required approach to the warning signal, the head poke was superior. But when the head poke required approach to the warning signal, the two responses were equally effective. Finding c depended on the absence of feedback for head poke during transfer. Two conclusions are offered: first, the two responses appear to obey the same laws when their topographical differences are taken into account. Second, response feedback appears to be more critical in transfer than in original acquisition.