Previous experiments have demonstrated that the simultaneous presentation of independently established discriminative stimuli can control rates of operant responding substantially higher than the rates occasioned by the individual stimuli. This "additive summation" phenomenon has been shown with a variety of different reinforcers (e.g., food,…

The acquisition of lever pressing by rats and the occurrence of unreinforced presses at a location different from that of the reinforced response were studied using different delays of reinforcement. An experimental chamber containing seven identical adjoining levers was used. Only presses on the central (operative) lever produced food pellets.…

Two experiments with pigeons investigated the effects of contingencies between interresponse times (IRTs) and the transitions between the components of 2- and 4-component chained schedules (Experiments 1 and 2, respectively). The probability of component transitions varied directly with the most recent (Lag 0) IRT in some experimental conditions…

Intraverbal behavior is common in conversation and academic and professional settings. Many individuals with disabilities fail to acquire intraverbal repertoires. Some individuals who do acquire intraverbal behavior fail to acquire responses that are functional and complete. Research has examined procedures to establish or increase intraverbal…

Animals must be able to find and evaluate food to ensure survival. The ability to associate a cue with the presence of food is advantageous because it allows an animal to quickly identify a situation associated with a good, bad, or even harmful food. Identifying genes underlying these natural learned responses is essential to understanding this…

In five experiments using rats, we investigated compound context-flavor conditioning. The subjects were allowed to spend time in the target context, where they had access to a flavored solution (either citric acid or saccharine) before receiving an injection of LiCl. Context aversion was then assessed by using a blocking procedure. When the flavor…

Cue competition is one of the most studied phenomena in associative learning. However, a theoretical disagreement has long stood over whether it reflects a learning or performance deficit. The comparator hypothesis, a model of expression of Pavlovian associations, posits that learning is not subject to competition but that performance reflects a…

Second-order conditioning (SOC) is the association of a neutral stimulus with another stimulus that had previously been combined with an unconditioned stimulus (US). We used classical conditioning of the proboscis extension response (PER) in honeybees ("Apis mellifera") with odors (CS) and sugar (US). Previous SOC experiments in bees were…

This paper reviews several issues regarding one- versus two-factor theories of learning. First, the traditional distinctions between classical and operant conditioning are presented. This includes both theoretical and experimental contrasts. Second, empirical evidence in support for a one-factor theory is examined. Numerous research studies…

A major concern of this report was to compare the effect of three verbal reinforcement combinations (VRCs) on the rate at which children learn a simultaneous two-choice discrimination problem. The experiments were designed to test the following: (1) whether relative effectiveness of the VRCs was dependent upon task complexity or subject age; (2)…

Major variables related to reinstatement of speech in hospitalized mute and near-mute schizophrenics were isolated and investigated. The study consisted of four parts: (1) verbal conditioning of mute and near-mute chronic schizophrenics using four experimental groups and two control groups, (2) four extra-laboratory measures for testing…

The discrimination of the onset of joint control is an important interpretive tool in explaining matching behavior and other complex phenomena, but the difficulty of getting experimental control of all relevant variables stands in the way of a definitive experiment. The studies in the present issue of "The Analysis of Verbal Behavior" illustrate…

Chen, Lakshminarayanan, and Santos (2006) claim to show in three choice experiments that monkeys react rationally to price and wealth shocks, but, when faced with gambles, display hallmark, human-like biases that include loss aversion. We present three experiments with monkeys and humans consistent with a reinterpretation of their data that…

More than 400 children with a physical and/or mental challenge visit the Curacao Dolphin Therapy and Research Center (CDTC) for dolphin-assisted therapy every year. Dolphin therapy appears to be the right approach for many children. With the help of these special and very social animals, it is easier to make contact with the children. It motivates…

The effects of prenatal choline availability on Pavlovian conditioning were assessed in adult male rats (3-4 mo). Neither supplementation nor deprivation of prenatal choline affected the acquisition and extinction of simple Pavlovian conditioned excitation, or the acquisition and retardation of conditioned inhibition. However, prenatal choline…