Reinforcement contrast effects in rats following experimental definition of a dimension of reinforcement magnitude.

Administered magazine training in 2 experiments to female albino Sprague-Dawley rats under 1 of 3 basic conditions: a 3,000-Hz tone followed by (a) 1 food pellet, (b) 10 food pellets, or (c) a quasi-random mixture of both 1 and 10 food pellets. Ss then learned to press a lever for either a 1-pellet or a 10-pellet reward. Results reveal significant and long-lasting negative-reinforcement contrast. When Ss pressed for 1 pellet after a mixed 1-and-10 pellet pattern during magazine training, they learned to lever-press more slowly than if they had been magazine trained with just the 1-pellet reward. Data do not show positive contrast, however. Results suggest that rats may form "abstractions" about patterns of reinforcing events to which a given reinforcer is compared when it is used to facilitate the acquisition of a new response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reward magnitude and partial reinforcement effects in a single runway.

The partial reinforcement acquisition effect (PRAE) in running speeds and the frustration effect (activity following nonreward compared with reward) were measured simultaneously in an alley whose goal-box floor was a stabilimeter. Experimental groups of 9 male Charles River albino rats each received 50 or 100% reinforcement combined factorially with 3 magnitudes of reward (1, 3, or 9 pellets). A control group of 18 Ss was never rewarded. The size of the PRAE was a direct function of reward magnitude, and crossing of 50 and 100% curves was found for all alley segments, including the goal segment. The frustration effect (FE) was present by the 2nd day of training for the 3- and 9-pellet groups, and the size of the FE was directly related to reward magnitude. The present study is unique in that (a) the findings were free from the effects of reward contrast, (b) behavior antecedent to the goal indicated that incentive was effectively manipulated, and (c) an unrewarded control group was used. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of a positive social reward upon a verbal avoidance response.

In investigating the effect of reward upon the acquisition and extinction of avoidance response, a word association task was presented to 90 Ss for 8 conditioning and 12 extinction trials. During conditioning, associations to preselected words were punished on Trial 1 and whenever S repeated them. There were 3 acquisition groups: 1 received the above training, the 2nd also received reward for substitute associations, and the 3rd obtained reward during the 2nd ? of acquisition only. Each acquisiton group was divided into 2 extinction subgroups: 1 received neither reward nor punishment while the 2nd was rewarded for avoiding. Results indicated that reward hastened acquisition and delayed extinction of avoidance responses, thus confirming hypotheses regarding the concept of secondary gain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Species generality of within-subjects reward magnitude effects.

12 female pigtail, stumptail, and squirrel monkeys and 4 female Holtzman albino rats were given acquisition, extinction, and reacquisition training in a discrete-trials 2-lever spatial discrimination situation. In acquisition the left and right levers were associated with 5- and 1-pellet rewards, respectively, and in reacquisition, response to either lever produced 5-pellet reward. The 4 species showed similar patterns of preference for the 5-pellet lever on 2-lever choice trials and differential responding on 1-lever forced trials in acquisition, and similar within-Ss extinction effects which were at variance with the typical crossover of large- and small-reward extinction curves in between-groups reward magnitude studies with rats. Species differences appeared in over-all relative rate of extinction, with the macaques showing the fastest extinction, and in the degree to which historical effects of acquisition conditions appeared and persisted in reacquisition. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Incentive shifts in the goldfish.

Trained 157 goldfish with a large or small magnitude of reward in a straight-alley runway. After 20 days of training with a given reward magnitude, 1/2 of the Ss in each group were shifted to the other magnitude of reward. Ss rapidly shifted swimming speeds when reward magnitudes were reversed. No contrast effects were observed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preference for unpredictable food rewards occurs with high proportion of reinforced trials or alcohol if rewards are not delayed.

A recently developed mathematical model (DMOD) also predicts that Ss prefer the unpredictable reward situation under conditions that substantially decrease aversiveness of unpredictable nonreward (Daly & Daly, 1982). Because a high proportion of reinforced trials (lenient schedule) and alcohol decrease aversive conditioning, these variables were tested with rats in 5 E-maze experiments. A choice to 1 side of the maze resulted in a stimulus uncorrelated with reward outcome (unpredictable). A choice to the other side resulted in stimuli correlated with reward and nonreward (predictable). Stimuli were not visible until after the choice was made. A lenient reinforcement schedule resulted in preference for the unpredictable reward situation if rewards were not delayed. Alcohol resulted in preference for the unpredictable reward situation if a medium 5-pellet reward was given. A lenient reinforcement schedule combined with an alcohol injection resulted in faster acquisition of the preference for the unpredictable reward situation than did a lenient schedule combined with a saline control injection. These results pose a major challenge to most theories, yet were predicted by DMOD. (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)     

Methylphenidate, amygdalectomy, and active avoidance performance in the rat.

64 male Sprague-Dawley amygdalectomized and control rats were given 400 active avoidance training trials in a shuttle box. Controls received 0, 4, 8, or 16 mg/kg of methylphenidate throughout acquisition. Amygdalectomized Ss were given the 1st 200 trials without drug, followed by 200 trials with drug. Administration of methylphenidate produced an abrupt and large improvement in performance in the amygdalectomized Ss. One month after acquisition under the drug, retraining without drug revealed a significant retention effect for the 3 amygdaloid-drug groups relative to the nondrug-amygdaloid group. Results indicate that although amygdalectomy impairs the performance of avoidance responses, it does not prevent the learning or retention of such responses. Since methylphendiate appears to act primarily on dopaminergic mechanisms, the possible influence of amygdalectomy on such mechanisms is discussed. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Persistence of runway performance after septal lesions in rats.

Assigned 32 male Wistar albino rats to groups receiving bilateral septal lesions or control operations. Septal lesions prevented the partial reinforcement extinction effect after 48 acquisition trials. Septal Ss showed increased resistance to extinction following continuous reinforcement but decreased resistance to extinction following partial reinforcement. Analysis of the acquisition data indicated that the lesions retarded the development of approach-avoidance conflicts associated with reward and nonreward. In a 2nd study, 16 septal and 16 control Ss received 96 acquisition trials. Extended training allowed the development of conflict responses under partial reinforcement, and the Ss with lesions were indistinguishable from controls during extinction. Following continuous reinforcement, septal lesions produced slower extinction of response. It is concluded that the lesions interfered with the development of feedback from frustration, approach-avoidance conflicts, and frustration tolerance. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retardation of jump-up escape responding in rats pretreated with different frequencies of noncontingent electric shock.

Pretreated 5 groups of 5 male albino Sprague-Dawley rats each with either 0, 10, 40, 80, or 160 5-sec, 1.5-ma pulsed shocks. Ss were then given escape training in a jump-up box. The number of failures to escape was an increasing function of pretreatment shock frequency. Ss that showed the retardation effect escaped irregularly with short latencies on some trials and failures to escape on others. After escape training, Ss in the 0-shock pretreatment group were given 80 5-sec, 1.5-ma pulsed shocks and then exposed to additional escape training in the jump-up box. These Ss did not show the retardation effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-punitive running in the rat following start box fear conditioning: Shock intensity effects.

In Phase 1 of an experiment with 240 female hooded rats, buzzer-alone presentations or buzzer-shock pairings were given in the start box of a 4-ft straight alley. Phase 2 consisted of runway test trials during which there was no shock in the alley or there was shock in the last 2 ft. Shock levels employed in each phase were 0, 40, 53, and 70 v. All Phase 1 nonshock Ss ceased running by Trial 3. In general, for Ss shocked in Phase 1, running speed and the number of Ss completing all 60 trials were greater for shocked than nonshocked Phase 2 conditions. In addition, the stronger the Phase 1 shock, the greater the number completing all trials and the faster the speeds. Phase 2 shock intensity was not a significant factor. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Magnitude and shift of reward in instrumental aversive learning in rats.

Conducted 3 experiments in which 4 groups of female hooded rats (N = 192) were given 35 classical fear-conditioning trials in 1 side of a 2-compartment box. Ss were then allowed to jump a hurdle to the adjacent box and escape the fear-eliciting stimuli. Reward magnitude (fear reduction) during hurdle jumping for 2 groups was either large or small throughout while for 2 groups it was increased or decreased after some training. Manipulated and nonmanipulated reward varied between experiments. Preshift performance was better with large than with small reward. Positive contrast effects were not found, but a negative contrast effect was obtained in Exp. III. The concepts of incentive motivation and frustration, used to account for performance in appetitively motivated learning tasks, are applied to the findings. (27 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of varied reward schedules on generalized persistence of rats.

Gave concurrent acquisition training to 4 groups of male albino rats (N = 70) in 2 parallel runways, such that continuous reward (CR) occurred in 1 alley and varied reward (VR) occurred in the other. The varied reward conditions were partial reward (PR), partial delay (PD), variable magnitude (VM), and constant delay (CD). A CR control group received CR in both alleys. All Ss were extinguished in the alley which had previously been associated with CR. Using resistance to extinction in the CR runway as the index of generalized persistence, the groups were ordered from greatest to least persistence as follows: PR, PD, VM, CD, and CR. This specific ordering is most easily accommodated by an elaboration of stimulus-aftereffects theory. (27 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ontogeny of passive avoidance learning in domestic chicks: Punishment of key-peck and running responses.

Determined the effect of the number of prepunishment acquisition trials on the age dependency of passive avoidance (PA) learning of the chick in keypeck and runway tests. In 9 experiments, 1- and 4-day-old Ss were first trained to respond for heat reward. After a variable number of reinforced acquisition trials (ATs), Ss' responses were punished with aversive wing shocks. Results show that the age dependency of PA learning of the young S is related specifically to the number of reinforced training trials given prior to PA testing. When several prepunishment ATs were given, 1-day-old Ss learned as quickly as 4-day-old Ss to withhold responding when punished. However, when only a few ATs preceded PA testing, 1-day-old Ss showed significantly less response suppression than 4-day-old Ss. Rather, results suggest that the 1-day-old chick, compared with the 4-day-old chick, is deficient in learning or detecting changes in stimulus– and/or response–reinforcement contingencies. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioning decreases in plasma corticosterone level in rats by pairing stimuli with daily feedings.

Examined the nature of a stimulus-induced decrease in the plasma corticosterone levels of male hooded Long-Evans rats in 3 experiments. Ss maintained on a 23-hr food and water deprivation regimen were fed each morning immediately upon entrance of the experimenter into the otherwise isolated animal quarters. After only 14 feeding trials, Ss showed a marked decrease in corticosterone levels within 10 min of the experimenter's entrance whether fed and watered or not. The acquisition of this decrease was then examined over training trials and by comparing the conditioned animals (Group CD) with a group designed to control for pseudoconditioning, sensitization, and habituation (Group PC) during the use of the more distinctive conditioning stimulus of placing the rat's cage in a sound-attenuating chamber. During training, Group CD was fed .5–6 min after placement in the chamber, and Group PC was fed 1.5–2.5 hrs before or after placement. After 1 training trial, the CD and PC groups showed an increase in corticosterone levels in response to chamber placement when not fed or watered. However, after 14 training trials the CD group exhibited a significant decline, whereas the PC group exhibited a rise in corticosterone levels. Results indicate that external stimuli can cause a decrease in corticosterone level by virtue of prior association with feeding and drinking. This strongly suggests an acquired inhibition of the pituitary-adrenal system. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of various forms of relaxation training on physiological and self-report measures of relaxation.

Examined the relative effectiveness of 4 types of relaxation training using electromyograph (EMG) and self-report measures of relaxation as dependent measures. Ss were 50 undergraduates. The experimental groups were (a) classic Jacobson-Wolpe instructions, (b) EMG feedback, (c) EMG feedback plus Jacobson-Wolpe instructions, and (d) EMG feedback plus a monetary reward. These groups were compared with each other and a no-treatment control group over 3 baseline and 12 training periods. All groups reported increased relaxation, but EMG measures showed that in speed of learning and depth of relaxation the EMG groups were superior to the Jacobson-Wolpe group, and the control group did not master relaxation at all. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of consistency of reward during runway training on subsequent discrimination performance in rats.

Describes 2 experiments with male albino Holtzman rats (N = 64). In Exp. I, Ss were trained under partial (PR) or continuous (CR) reward in a gray or striped runway and were then trained on a simultaneous stripe-orientation discrimination. PR caused a decrement in discrimination performance after training in the striped runway but had no effect after training in the gray runway. In Exp. II, Ss received PR, CR, or no training in a runway with stripe cues on the floor of the runway varying randomly in orientation. All Ss were then trained on a simultaneous compound-cues discrimination with orientation and width of stripes relevant. After reaching criterion each S was given single-dimension tests on each dimension. PR Ss performed worse on orientation tests but not on width tests. Results are interpreted as supporting stimulus-analyzer theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selection versus training in the development of paraprofessionals.

To investigate the relative contributions of selection and training on the performance of paraprofessionals, 80 undergraduate volunteers responded to simulated phone calls. Ss were randomly divided into 4 samples, and 1 group was chosen from each sample. Two groups were chosen on the basis of high scores on the Telephone Counseling Effectiveness Scale (TCES), which was used to rate the responses to the phone call, and 2 groups were chosen randomly. One selection group and one random group were trained in 3 2-hr training sessions. All Ss were then asked to respond to the call again, and once again 3 wks later. All calls were rated using the TCES. Using an analysis of covariance, training was found to have a significant main effect, while selection was not. There was also a 3-way interaction between training, selection, and test. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Le transfert interhémisphérique d'apprentissages visuels chez le chat à cerveau divisé: Effets de la situation expérimentale.

Demonstrated that the amount of residual interhemispheric transfer of pattern discrimination in split brain cats can be influenced by the nature of the training task. Three groups of Ss that had been subjected to an optic chiasma and a corpus callosum transection were each trained and tested for transfer in 1 of 3 experimental conditions: (1) the classical 2-choice discrimination apparatus with food reward; (2) a similar apparatus with incorrect trials punished with a painful electric shock; or (3) a Lashley-type jumping stand adapted for cats. Ss were tested on a number of patterns using either one or the other eye for learning and the naive eye for transfer testing. Results indicate that Ss tested in the 1st method showed no transfer, Ss given shocks for incorrect responses became neurotic, and Ss trained in the jumping stand showed no immediate transfer but rather good saving. Better transfer performance of the 3rd group may be a result of motivational factors in the testing situation and possibly increased facility to use secondary cues such as head and/or eye movements to make their discriminations. (English abstract) (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of varied preshift reward magnitude on successive negative contrast effects in rats.

A total of 110 male Sprague-Dawley albino rats, distributed across 3 experiments, received simple instrumental conditioning trials in a straight runway. In each experiment the conditions of reward prior to a shift to small reward were varied between groups. Collectively, results indicate that the extent of the negative contrast effect depends upon the difference between pre- and postshift incentive levels and that Ss exposed to varied reward magnitude training average the incentive values of these rewards. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)