Extinction and retention of a classically conditioned flexor nerve response in acute spinal cat.

Conditioned adult male and female cats by pairing a mild electrical stimulus to the superficial peroneal sensory nerve (CS) with a stronger electrical stimulus to the ankle skin (UCS) of the same leg. Subsequent extinction was produced by presenting CS-alone trials. In Exp I (42 Ss), Ss given massed extinction trials showed response decrements to base levels, but Ss that received distributed extinction trials showed no decrements. In Exp II, .5-, 1-, 2-, 3-, or 4-hr intervals between acquisition and extinction produced no significant differences in the extinction data. In Exp III (20 Ss), Ss received extinction trials immediately or 30 min after acquisition trials, followed by 20 additional extinction trials 30 min later. Data indicated significant acquisition and extinction in the 10- and 20-acquisition trial groups. As in Exp II (35 Ss), varying the interval between acquisition and extinction did not produce any group differences in the extinction data. These results demonstrate that response increases produced by paired trials in the spinal preparation do not decay spontaneously over time and are not caused by sensitization effects. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of exposure to conditioned stimulus and control of its termination in the extinction of avoidance behavior.

Describes 2 experiments in which, following signaled shuttle box avoidance training, a total of 52 female Fischer344 rats were exposed to the conditioned stimulus (CS) during no-shock treatment trials and subsequently tested during extinction trials in which shock was also absent. In Exp I, Ss that could control the termination of the CS during treatment responded significantly more often during extinction than yoked partners that received the same pattern and duration of CS exposure but could not control its termination. Exp II revealed that the probability of responding during extinction was a decreasing function of the duration of CS exposure during treatment. Thus, in the absence of shock, both lack of control over CS termination and increasing CS exposure each independently facilitated the weakening of well-established avoidance responses. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retention of response persistence in weanling and adolescent rats.

Two experiments (192 Sprague-Dawley rats) examined parameters affecting retention of continuously reinforced (CRF) and partially reinforced (PRF) runway training in weanling and adolescent Ss. In Exp I, weanling Ss were given CRF or PRF training and 12 hrs, 3 days, or 10 days later were given 8 CRF reacquisition trials followed by extinction. In Exp II, weanling and adolescent Ss were given CRF or PRF runway training and extinguished 10 days later following 0, 8, or 24 CRF reacquisition trials. Results suggest that (a) weanlings characteristically display a partial reinforcement extinction effect (PREE) of unusually large magnitude if extinguished within 12 hrs of training, (b) this large-magnitude PREE dissipates within 3 days of training regardless of the number of CRF reacquisition trials preceding extinction, (c) no PREE of any magnitude is seen in weanlings or adolescents following a 10-day interval unless CRF reacquisition trials precede extinction, and (d) retention of the PREE is poor or nonexistent in Ss trained as adolescents and extinguished 10 days later, even with CRF reacquisition preceding extinction. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Punishment and the length of non-shock confinement during the extinction of avoidance.

Groups of 72 male Sprague-Dawley rats, trained to avoid in an alley with 3 distinct chambers, spent either 2, 15, or 30 sec. in the safe or goal chamber (GB) during extinction, with the remainder of the constant 150-sec intertrial interval (ITI) spent in the start box (SB). 1/2 the Ss of each group were punished (shocked) in the middle chamber during extinction, 1/2 were not. It was found that (1) the longer the goal confinement, the greater the resistance to extinction; regular extinction groups extinguished faster than the punished; and (3) there was no significant interaction between GB confinement and the punishment variable. During extinction in Exp. 2 there were 2 levels of goal confinement (2 vs. 30 sec.), equal time spent in SB in all groups, a constant ITI of 62 sec., and punishment vs. no punishment. 48 male Sprague-Dawley rats served as Ss. As anticipated, punishment prolonged extinction only for the 30-sec GB confinement; the other 3 groups extinguished at approximately the same rate. The concept of short-latency "relief" was invoked to explain this significant interaction. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Counterconditioning versus forced exposure in extinction of avoidance responding and conditioned fear in rats.

Conducted 2 experiments using 64 and 32 male Long-Evans hooded rats, respectively. Exp. I investigated the extinction of the conditioned avoidance response (CAR) by response prevention and counterconditioning methods. Response prevention was most effective in extinguishing both the CAR and associated conditioned fear, although counterconditioning produced greater extinction than the regular extinction procedure. Exp. II equated the counterconditioning and response-prevention conditions for duration of CS exposure and demonstrated the superiority of the latter in extinguishing the CAR; both methods were equally effective in decreasing conditioned fear as compared to the regular extinction procedure. Extinction of the CAR was facilitated to the extent to which different procedures eliminated response-contingent feedback by reducing escape-avoidance responses. Conditioned fear was a function of the amount of nonreinforced exposure to the CS during extinction. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of classical conditioning on an internal clock.

Six experiments with 53 male Charles River rats used a psychophysical choice procedure to study the internal clock used to discriminate duration and to investigate whether this clock is sensitive to the signal value (associative strength) of a stimulus. The experiments involved 2 types of trials: On choice trials, a stimulus lasted a short (e.g., 3-sec) or long (e.g., 12-sec) duration; Ss then chose between 2 levers. The rewarded choice depended on the duration of the stimulus. On conditioning trials, the stimulus used on choice trials was presented, but it ended without food (extinction trials) or with food (pairing trials) regardless of what the S did. The main measure of performance was short bias, defined as accuracy with the short stimulus without a corresponding accuracy with the long stimulus. Exp I showed that extinction trials increased short bias relative to training without conditioning trials or to training with pairing trials. Exps II–VI tested explanations of these results. The same results were found when extinction trials were the same duration as the short stimulus (Exp II), when extinction trials were a random duration (Exp V), and when the signal value of the CS was changed in another way (Exp VI). The effect of conditioning trials was modality specific (Exps III and IV). It is concluded that, of the explanations considered, the most valid is that changing the signal value of a stimulus changes how the clock times the stimulus. Reducing signal value reduces the measured duration. (54 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Appetitive learning and extinction in 11-day-old rat pups: Effects of various reinforcement conditions.

Studied the acquisition and extinction of approach behavior in 96 11-day-old albino Sprague-Dawley rat pups in 3 experiments. The reinforcement in Exps I & II was 15 sec of nonnutritive suckling on an anesthetized lactating female. In Exp I, detention duration, 0- or 15-sec in the goal box on nonreward (N) trials, was studied in 2 groups whose acquisition training consisted of alternating blocks of rewarded and nonrewarded trials with a short (5-sec) intertrial interval. Exp II combined an examination of the effect of detention length with whether or not the mother was physically present, though inaccessible, on N trials with partially or continuously rewarded groups. Detaining Ss on N trials slowed the rate of extinction when the mother was present but increased the rate of extinction when she was absent. There was no evidence of a partial reinforcement extinction effect in any of the groups. The effectiveness of 6 types of reinforcement on promoting acquisition of approach behavior was assessed in Exp III. Equally good acquisition, but differences in extinction was obtained with an adult conspecific as the reinforcer, independent of sex and suckling, but there was no acquisition of approach responding when a sibling or no conspecific was in the goal box. These data extend earlier findings of appetitive learning and extinction in infant rats. They do not support the view that inhibitory mechanisms are absent in the rat until the 3rd or 4th wk of life. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discriminative shock-avoidance learning of an autonomic response under curare.

Assigned 16 curarized, artificially respirated male Sprague-Dawley albino rats to 2 groups of 8 Ss each, rewarded for intestinal contraction (C) or relaxation (R), respectively. Each S received a predetermined series of CS+, CS-, and blank (B) trials, the latter involving no stimulation. On CS+ trials, Ss in Group C received a noxious electric shock to the tail for episodes of intestinal relaxation, while those in Group R received the shock for episodes of intestinal contraction. Results indicate that both groups spent significantly greater amounts of time, both toward the end of acquisition and during extinction, in the intestinal state for which they were rewarded, manifesting stimulus-specific escape and avoidance learning. In Exp. II with 4 curarized Ss, no consistent unconditioned effects on intestinal motility were observed as a result of shock application or shock offset. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The opioid/nonopioid nature of stress-induced analgesia and learned helplessness.

Investigated whether the same factors that activate the processes that produce escape interference might also activate processes leading to opioid stress-induced analgesia (SIA). Exposure to a variety of stressors produces a subsequent analgesic reaction that is sometimes opioid in nature (reversed by opiate antagonists and cross-tolerant with morphine) and sometimes nonopioid. In Exp I, 40 male albino rats were subjected to 20 min of intermittent footshock, 3 min of continuous footshock, tailshock on a VI schedule, or confinement only. Ss were given escape/avoidance training 24 hrs later. In Exp II, 36 Ss received SIA with a tail-flick apparatus. In Exp III, 40 Ss received inescapable tailshocks or confinement only. In Exp IV, 24 Ss received 2 sessions of footshock before tail-flick was assessed. Both of the opioids SIA procedures produced a learned helplessness effect as assessed by shuttlebox escape acquisition and an analgesia that was reinstatable 24 hrs later. The nonopioid procedures produced neither a learned helplessness effect nor a reinstatable analgesia. These data implicate the learning of uncontrollability in the activation of opioid systems. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioning and extinction of avoidance and escape behavior in neonatal dogs.

Ran 16 neonatal purebred beagles for 6.5 days in a 1-way shuttle box with cold air as the aversive stimulus. 8 Ss started at 1 day of age and 4 each started at 2 and 3 days of age. 8 Ss received escape conditioning and 8 received avoidance conditioning. Following this training, both groups were given a series of extinction trials. Both escape and avoidance conditioning and extinction were obtained. Findings are comparable to previous avoidance findings in neonatal dogs and superior to findings on neonatal mice and kittens. Results display quantitative properties found in studies of adult rats and especially adult dogs. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An evaluation of spatial information processing in aged rats.

The spatial learning abilities of young, middle-age, and senescent rats were investigated in 2 experiments using several versions of the Morris water maze task. In Exp I, Long-Evans hooded rats were trained to find a submerged escape platform hidden within the water maze. Aged Ss exhibited acquisition deficits compared with either young or middle-age Ss. With continued training, all age groups eventually achieved comparable asymptotic levels of performance. To identify the basis of the age-related impairments observed in Exp I, naive young and aged Ss in Exp II were initially tested for their ability to locate a cued escape platform in the water maze. The escape latencies of both young and aged Ss rapidly decreased to equivalent asymptotic levels. Following cue training, young Ss exhibit a significant spatial bias for the region of the testing apparatus where the platform was positioned during training. In contrast, aged Ss showed no spatial bias. Training was continued in Exp II using a novel submerged platform location for each S. During these place training trials, the escape latencies of senescent Ss were longer than those of young Ss. These impairments were also accompanied by a lack of spatial bias among aged Ss relative to young controls. Results indicate that age-related impairments in water maze performance reflect a specific deficit in the ability of aged rats to utilize spatial information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Similarity between shock and safe areas during acquisition, transfer, and extinction of escape behavior in rats.

Demonstrated, in 3 experiments with a total of 128 female hooded rats, that performance in escape training was impaired when shock- and safe-box stimuli were similar rather than dissimilar to each other. Prior training with similar shock and safe boxes impaired responding during subsequent training or extinction under the dissimilar shock and safe condition. Prior training under the dissimilar condition did not reliably influence subsequent training or extinction under the similar shock-safe condition. Resistance to extinction under the dissimilar condition was reliably better following training with random presentations to both similar and dissimilar conditions than following training with the dissimilar condition alone. Exp III showed that impairment of escape behavior during training was attributable to response-contingent similarity between shock and safe boxes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of acute trimethyltin exposure on appetitive acquisition and extinction performance in the adult rat.

16 adult male Sprague-Dawley rats were given an intragastric infusion of 7 mg/kg of trimethyltin chloride (TMT), and 16 additional Ss (controls) received saline, to investigate TMT's effect on Ss' appetitive acquisition and extinction performance. Ss from each condition were divided into 2 equal groups and trained with either partial or continuous reinforcement (PRF or CRF) in a straight-alley maze 21 days after dosing. The acquisition training phase contained 40 trials (4 trials/day) and was followed by 20 trials of extinction training (4 trials/day). Analyses performed on total speed revealed that TMT Ss performed at lower levels during acquisition than controls, regardless of schedule condition. Also, the rate of resistance to extinction was significantly reduced for TMT Ss compared with that of controls, regardless of the training schedules used during acquisition. A PRF extinction effect was observed for both control and TMT Ss, independent of dose regimen. PRF training occasioned greater persistence during extinction than did CRF training. Findings are discussed in terms of issues relating to TMT-induced hippocampal lesions. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Erratum: "Studies in Early Infant Learning: Classical Conditioning of the Neonatal Heart Rate."

Reports an error in the original article by D. H. Crowell et al (Developmental Psychology, 1976[Jul], 12(4), 373-397). Corrections to equations 1, 2, and 3 on pages 381 and 382 are presented. (The following abstract of the original article appeared in record 1976-20687-001.) Three experiments demonstrated that human newborn heart rate level can be reliably modified through classical conditioning procedures. The theory of sensitization served as a frame of reference for Exps I and II, and drive reduction served for Exp III. In Exp I the delay, delay-trace, and control groups, with 10 2-day-old newborns in each, received 5 preconditioning trials of the CS alone, 16 conditioning trials with CS-UCS pairings differing for each group, and 5 extinction trials. Exp II was a replication of the 1st study and involved only the delay and delay-trace groups with 10 infants each. In both studies the delay group curves showed significant monophasic acceleratory responses during extinction. Results support the sensitization hypothesis (i.e., the CR occurring in the interstimulus interval was fashioned out of the response to the CS). In Exp III, the measure of conditioning was the response to the probe technique. 10 experimental Ss received preconditioning trials of nitrogen puff (UCS-sub-1) administered to the abdomen, followed by 10 CS-UCS-sub-2 (500-Hz tone acetic acid) pairings with an interstimulus interval of 3 sec. 10 controls received the same design with a CS-UCS-sub-2 interval of 40 sec. Analyses of the probe stimulus trials showed significant changes for the control group and none for the experimental group. The CS-UCS-sub-2 pairings in the experimental group are interpreted as producing increased drive and adaptive damping of the heart rate response. Findings show that early learning may occur under a variety of conditions and that the results can be incorporated by different theories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of intertrial reinstatement of training stimuli on complex maze learning in rats: Evidence that "acquisition" curves reflect more than acquisition.

In Exps I–III (224 male Sprague-Dawley rats), Ss were run in a complex maze to escape weak footshock or to approach an appetitive reinforcer. Extramaze intertrial reinstatement of the same reinforcer as that used in training was found to enhance subsequent maze performance. Exp IV (80 Ss) determined that appetitively and aversively motivated performance benefitted from brief intertrial exposures to the start box of the maze. In Exp V (64 Ss), a facilitatory effect indicated that memory trace activity need not be maintained between training and reinstatement or between reinstatement and subsequent training. Exp VI (80 Ss) examined the effects of reinstatement at the beginning, middle, or end of 5-min intertrial intervals and found enhanced performance in the last 2 conditions. Exp VII (24 Ss) established that 4 successive reinstatement treatments without interpolated training trials were no more beneficial than a single reinstatement. Exp VIII (16 Ss) determined that forgetting had occurred over the standard 5-min interval between training trials. Exp IX (32 Ss) found that reinstatement alleviated forgetting that had already transpired. (49 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The time course of perceptual and conceptual contributions to word fragment completion priming.

Two experiments examined the time course of the availability of perceptual and conceptual information in priming on the word fragment completion test. Ss encoded primes as either visual words, auditory words, or pictures. In Exp 1, word fragments were exposed for either 500 msec, 1 sec, 5 sec, or 12 sec. Only the visual words produced priming at the 500-msec and 1-sec exposure times. In Exp 2, Ss were allowed up to 20 sec to solve each fragment; response latencies were recorded, and cumulative response curves were generated. Visually primed fragments were solved at a faster rate than either auditorily or pictorially primed fragments. The results suggest that although conceptual processing can contribute to word fragment priming, perceptual processes are recruited earlier and at a faster rate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Specificity of process, response, and stimulus in behavioral bioassays.

Reported 3 experiments which studied aspects of the behavioral specificity of the "biochemical transfer" phenomenon. In Exp I, using 120 common goldfish, an acquisition extract facilitated acquisition but not extinction, while an extinction extract facilitated extinction but not acquisition. In Exp II, using 60 Ss from Exp I and 20 additional Ss, brain extracts facilitated an avoidance response only if they originated in donors that made that same response; extracts from donors that did not respond, although exposed to identical stimuli, did not modify recipient behavior. In Exp III, the biochemical transfer effect was found to be stimulus specific in 48 large and 111 small Ss. Results suggest that the extracts in question are behavior specific and do not generally affect behavior in a global excitatory or global inhibitory way. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Studies in early infant learning: Classical conditioning of the neonatal heart rate.

Three experiments demonstrated that human newborn heart rate level can be reliably modified through classical conditioning procedures. The theory of sensitization served as a frame of reference for Exps I and II, and drive reduction served for Exp III. In Exp I the delay, delay-trace, and control groups, with 10 2-day-old newborns in each, received 5 preconditioning trials of the CS alone, 16 conditioning trials with CS–UCS pairings differing for each group, and 5 extinction trials. Exp II was a replication of the 1st study and involved only the delay and delay-trace groups with 10 infants each. In both studies the delay group curves showed significant monophasic acceleratory responses during extinction. Results support the sensitization hypothesis (i.e., the CR occurring in the interstimulus interval was fashioned out of the response to the CS). In Exp III, the measure of conditioning was the response to the probe technique. 10 experimental Ss received preconditioning trials of nitrogen puff (UCS?) administered to the abdomen, followed by 10 CS–UCS? (500-Hz tone acetic acid) pairings with an interstimulus interval of 3 sec. 10 controls received the same design with a CS–UCS? interval of 40 sec. Analyses of the probe stimulus trials showed significant changes for the control group and none for the experimental group. The CS–UCS? pairings in the experimental group are interpreted as producing increased drive and adaptive damping of the heart rate response. Findings show that early learning may occur under a variety of conditions and that the results can be incorporated by different theories. (79 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Type of start box and goal box distinctiveness in self-punitive running of rats.

A total of 96 male Sprague-Dawley rats were first trained to escape shock in an alley by running to a safe goal box. In Exp I either a trapdoor-floored start box or a guillotine-door start box was used in different groups. In extinction, nonpunished and punished subgroups were tested in each of the start-box conditions. Punishment produced faster running speeds than nonpunishment (self-punitive effect) only with the trapdoor. The trapdoor start box was used in Exp II, and independent groups of Ss were trained to escape to a goal box that was either very dissimilar or similar to the shock area. Nonpunished and punished subgroups were extinguished in each goal box condition. Self-punitive running was more likely with the dissimilar goal box. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

False feedback and longevity of the conditioned GSR during extinction: Some implications for aversion therapy.

Investigated the effects of 2 cognitive variables on GSR extinction rates. Exp. I replicated findings that Ss made aware of the onset of nonshocked trials exhibited extinction of a conditioned emotional response more rapidly than Ss not made aware. Exp. I and II (80 and 20 Ss, respectively) further demonstrated that extinction, even under conditions of awareness, can be significantly retarded when false feedback concerning the S's current emotional responsivity is supplied during extinction trials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)