Analyzing the random control procedure: Effects of paired and unpaired CSs and USs on autoshaping the chick's key peck with heat reinforcement

Incentive salience attribution under reward uncertainty: A Pavlovian model

There is a vast literature on the behavioural effects of partial reinforcement in Pavlovian conditioning. Compared with animals receiving continuous reinforcement, partially rewarded animals typically show (a) a slower development of the conditioned response (CR) early in training and (b) a higher asymptotic level of the CR later in training. This phenomenon is known as the partial reinforcement acquisition effect (PRAE). Learning models of Pavlovian conditioning fail to account for it. In accordance with the incentive salience hypothesis, it is here argued that incentive motivation (or 'wanting') plays a more direct role in controlling behaviour than does learning, and reward uncertainty is shown to have an excitatory effect on incentive motivation. The psychological origin of that effect is discussed and a computational model integrating this new interpretation is developed. Many features of CRs under partial reinforcement emerge from this model.

Acquisition with partial and continuous reinforcement in rat magazine approach

Partial reinforcement, compared with continuous reinforcement, is widely considered detrimental to Pavlovian conditioned responding. However, time-accumulation models predict an invariance in acquisition when learning is assessed as a function of number of reinforcements, not trials, and intertrial interval is held constant. Three experiments examined this prediction in a rat magazine-approach procedure. All experiments showed superior responding with continuous reinforcement. Experiments 1 and 3 used common tests in between- and within-subject designs, respectively. Experiment 2 showed the same pattern in a discrimination. Earlier results are reanalyzed informally and in a meta-analysis. Contrary to previous summaries of the literature, evidence points to superior conditioned responding with continuous reinforcement in a number of procedures. Results are generally consistent with traditional associative models of learning.

Acquisition with partial and continuous reinforcement in pigeon autoshaping

Contemporary time accumulation models make the unique prediction that acquisition of a conditioned response will be equally rapid with partial and continuous reinforcement, if the time between conditioned stimuli is held constant. To investigate this, acquisition of conditioned responding was examined in pigeon autoshaping under conditions of 100% and 25% reinforcement, holding intertrial interval constant. Contrary to what was predicted, evidence for slowed acquisition in partially reinforced animals was observed with several response measures. However, asymptotic performance was superior with 25% reinforcement. A switching of reinforcement contingencies after initial acquisition did not immediately affect responding. After further sessions, partial reinforcement augmented responding, whereas continuous reinforcement did not, irrespective of an animal's reinforcement history. Subsequent training with a novel stimulus maintained the response patterns. These acquisition results generally support associative, rather than time accumulation, accounts of conditioning.

The conditioning of human sexual arousal

Although most theories of human sexual behavior claim that much normal sexual behavior is learned, and theories of the etiology and modification of paraphilic and dysfunctional sexual behavior also claim that abnormal sexual behavior is learned and can be counterconditioned, there is no systematic review examining the relationship between conditioning and human sexual behavior. We review research addressing whether habituation, sensitization, classical conditioning, and operant conditioning processes are involved in human sexual behavior. We conclude that, due to the methodological problems of extant studies, the basis for asserting the existence of relationships between habituation, sensitization, classical conditioning, operant conditioning, and sexual behavior is tenuous.

Thermoregulation and performance of heat-reinforced autoshaped keypecking in chicks

Performance of autoshaped keypecking reinforced by heat was found to increase and then to decrease when chicks were exposed to training under a constant thermal load on a daily basis over the first 1-2 weeks after hatching. The decline in performance was not affected by variation in US duration (Experiment 1). No decline in performance was observed when food reinforcement was used (Experiment 2), suggesting that the effect depended on the use of thermal motivation. When thermoregulation was disrupted by pharmacological blockade using propranolol hydrochloride (10 mg/kg), keypecking was reinstated (Experiment 3). The increase in keypecking produced by propranolol was not due to a nonspecific energization of behavior inasmuch as the drug depressed autoshaped keypecking established with food reinforcement (Experiment 4). These findings support the conclusion that the decline in autoshaped keypecking reinforced by heat is due to development of the chick's thermoregulatory system. Various physical changes (e.g., feathering) and the increasing effectiveness of autonomic and behavioral thermoregulatory responses reduce the net motivational value of external heat sources, thus leading to a decline in the likelihood of approach and contact with signals for heat.