Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The aim of this study was to assess the viability and potential efficacy of an environmental tobacco smoke (ETS) exposure reduction intervention for atrisk children. The study consisted of a 12-week behavioral intervention and a 6-month follow-up, conducted on a convenience sample (N=43) of lowincome, self-identified, adult smokers who were caregivers of 3-5 year old children. The intervention included a manualized program, plus nicotine replacement therapy, and monetary reinforcement of abstinence. Outcome measures included breath carbon monoxide (CO), self-reported smoking practices, level of nicotine dependence, and depression symptoms. Significant reductions were observed in CO concentration, frequency of smoking around children, and nicotine dependence and depression scores. Sixty-one percent of the participants attended 8 or more weekly sessions, and one third remained smoke-free at follow-up. Those who did not quit reported not changing their smoking behavior patterns in vehicles or indoors. The cessation intervention compared well with other interventions for treatment-seeking smokers, suggesting that implementing evidence-based cessation and education programs for caregivers at school sites may be effective in reducing daily exposure to ETS of pre-school children.

Tolerance is stronger when the drug is administrated in the context that signals the presence of the drug. This study was designed to evaluate the effect of context on development of tolerance to diazepam and cross tolerance diazepam- ethanol, on exploratory activity in the elevated plus maze (EPM) and in motor activity. Male Wistar rats were assigned to independent groups (n =8). In Experiment 1, the effect of acute administration of ethanol (1.5 mg/kg) and diazepam (1mg/kg) was evaluated. In Experiment 2, the effect of context was evaluated on the development of tolerance: two chronic groups received 20 administrations of diazepam in different contexts, one in the Colony Room context and other in the Laboratory context, the Control group received 21 administration of saline in equivalent volume (1ml/kg) in the Laboratory context; on test day all groups were evaluated in the Laboratory context. In Experiment 3, following the same procedure, the effect of context was evaluated on the development of cross tolerance diazepam-ethanol. Immediately after exposure on the ETM, motor activity was evaluated in all groups. Diazepam and ethanol produced anxiolysis (Experiment 1); the chronic groups developed tolerance independently of the context, although it was stronger in the context associated with the drug (Experiment 2). In Experiment 3, the development of cross-tolerance diazepam-ethanol and the effect of context were observed.

An observational technique for measuring individual water consumption is presented, which assesses diverse domestic uses of water. The recording is conducted by previously trained housewives in an attempt to obtain a reliable, valid assessment that minimizes the inconveniences of classical observational techniques, such as the intrusion from observers and the subsequent reactivity of the observed people. The water consumption of 510 individuals was recorded, computing through three days in a week the time invested by the observer and two other persons at her household in washing dishes, taking a shower, watering plants, tooth- brushing, and watering the sidewalk in front of their households. Results of the recording indicated stability and internal consistency of the measures, revealing reliability of the instrument. A confirmatory factor analysis indicated evidence of convergent construct validity, which was reinforced by a significant correlation between the observations and the meter-recording of water consumption. Also, an evidence of concurrent validity was obtained when correlating these observations with scales assessing utilitarian and ecological beliefs regarding water.

Two experiments were conducted, each with 12 male albino Wistar rats. The effect of delivering water in the 20 initial or final cycles of a temporally defined schedule upon the total number of responses per session was evaluated, regardless of the total number of obtained water deliveries. Water delivery was contingent to the first response during the tD period of each cyle and, in addition to that, if animals did not respond in the selected first or final blocks of cycles, water also was delivered noncontingently at the end of its tD period. tD and tΔ periods were signaled by different exteroceptive stimuli. Experiment 2 was similar to Experiment 1, except that a retractable lever was withdrawn right after water delivery when animals responded during the tD periods of the selected cycles and was not reinserted until the beginning of the next cycle. Results show that the total number of responses in a session seems to depend both on the frequency of responses associated to local water deliveries and on the total number of water deliveries, regardless of its distribution within a session. Results are discussed according to the intruded stimulus paradigm.

Using a free-choice experimental task with rats (Rattus norvegicus), the effect of the magnitude and the probability of reinforcement was studied. Both variables were manipulated in two different alternatives of response, being equal the quantity of reinforcer on each alternative at the end of the experimental session. Initially, the rats were sequentially trained on two alternatives of response (forced-choice): 1) to get with high probability of reinforcement less magnitude of reinforcer (risk aversion) and 2) to get with low probability of reinforcement more quantity of reinforcer (risk prone). After the training, both alternatives of response were simultaneously presented (free-choice). In general, rats were risk averse. Nevertheless, a fine-grain analysis shows an interaction effect between both variables considered. This effect conveys about the possible risk propensity of the rats when these variables are combined into the same experimental preparation.

In a simulated public goods dilemma, framed as “saving” and “invest” games, 26 undergraduate students were instructed to play themselves, but in fact they interacted with a computer. Each subject participated once in a series of 45 independent single-trial dilemmas. On each trial participants received an endowment of five points to decide whether or not to contribute it for the provision of a public good. In order to evaluate the effects of group size to determine how much subjects contribute, they received information indicating that their group was relatively cooperative (80%) with a provision point of 24 units. A significant effect of group size was found, with participants in the small group condition emitting more cooperative responses. Findings suggest that the effect depends on the particular sequence of experimental phases. Results lend some support to the conditional cooperation explanation. Our central focus was on the two dimensions of response available to subjects: adjustments in their individual contribution, and willingness to gain control of the interchange. The observed differences and the regulation factors of group size are discussed.

Correspondence training is a procedure used to promote, eliminate, weaken or increment a target behavior through the verbalization of future or past correspondent behaviors. In this experiment, a second-order matching-to-sample task was modified to train subjects from two different school populations into different correspondence training histories (saying-doing, doing-describing and saying-describing) in order to analyze the effects of correspondence training on acquisition and generalization of the conditional discrimination. Correspondence training interfered with the acquisition of matching to sample and those subjects who learnt the conditional discrimination did it under the transfer test condition. These results suggest that the establishment of correspondence among what a subject says he is going to do, what he does and what he describes that did may be associated to functional intervention of feedback, that is, to the way feedback promotes that a factor or the relation of two factors of the matching-to-sample task appears with a greater relative weight than the other elements of the contingencial relations trained.

One purpose of this study was to determine if by correlating each component of a multiple schedule with delays-of-reinforcement of either 0, 2, 4, or 8 s, a within-session delay-of-reinforcement gradient could be obtained. Reinforcement was delivered on each component using a tandem schedule composed by a random interval that added to each nominal delay yielded a constant interreinforcement interval (IRI) of either 32 or 128 s. Three pigeons were assigned to each IRI. Response rates in each component of the multiple schedules decreased gradually as the reinforcement delay was lengthened. A second purpose was to determine the point on a continuum defined by the probability of signaling the delay period p(signal) at which frequency-of-reinforcement effects become relative-time effects in a reinforcement-delay procedure. The p(signal) was either 0.00, 0.33, 0,66 or 1.00. When p(signal) was 0.00, global response rates for any given delay were higher with the 32 s than with the 128 s IRI, showing a frequency-of-reinforcement effect. When p(signal) was increased from 0.33 to 1.00 global response rates for any given delay were higher with the 128 s than the 32 s IRI, showing a relative-time effect.

Previous attempts to condition schedule-induced drinking (SID) to formerly neutral stimuli have involved Pavlovian-conditioning procedures. Such strategy has yielded mixed results. According to the idea that SID may reduce to the operant conditioning of the water-producing response with water as its reinforcer, the establishment of stimulus control on SID was attempted using an operant-discrimination procedure. Three food-deprived rats were exposed to mixed and multiple schedules of water-reinforcement. In 32 s reinforcement components, lever pressing produced water according to a random-interval 6 s schedule. In 64 s extinction components, lever pressing did not produce water reinforcement. Food pellets were delivered concurrently according to a random-time 60 s schedule. For all rats, the rate of lever pressing was similar in both components when the mixed schedules were in effect. When the multiple schedules were in effect response rates were higher in the waterreinforcement components than in the extinction components. These results show that SID can be subjected to an operant discrimination and support the idea that SID reduces to the known principles of operant conditioning.