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School violence is a serious social and public health problem prevalent worldwide. Although the relevance of teacher and classroom factors is well established in the literature, few studies have focused on the role of teacher perceptions in school violence and victimisation and the potential mediational role of classroom climate in this relationship. A total of 2399 adolescents (50% girls), aged between 11 and 18 years (M = 14.65, SD = 1.78) and enrolled in five Spanish Secondary Compulsory Education schools completed measures of classroom climate, school violence towards peers and perception of peer victimisation, and their teachers informed about their academic competence and the teacher&ndash, student relationship. Correlational analyses revealed that whereas academic competence perceived by the teacher was negatively related to overt violence and victimisation, its relationship with pure relational violence was positive. Structural equation modelling analyses showed that variables of classroom climate (involvement, affiliation, and teacher support) perceived by the students functioned as partial mediators between teacher perceptions of academic competence and of teacher&ndash, student relationship and violence and victimisation. In the mediational model, teacher perception of academic competence acted as a direct protective factor against violence and victimisation, and teacher perception of teacher&ndash, student relationship acted as a direct risk for violence, as well as an indirect protective factor through classroom climate for victimisation. The interpretation of these results points to the importance of the teacher&rsquo, s subjective perceptions in the prevention of violence and victimisation problems and their practical implications for the classroom climate perceived by students.

Previous studies have demonstrated that the differential outcomes procedure (DOP), which involves paring a unique reward with a specific stimulus, enhances discriminative learning and memory performance in several populations. The present study aimed to further investigate whether this procedure would improve face recognition memory in 5- and 7-year-old children (Experiment 1) and adults with Down syndrome (Experiment 2). In a delayed matching-to-sample task, participants had to select the previously shown face (sample stimulus) among six alternatives faces (comparison stimuli) in four different delays (1, 5, 10, or 15 s). Participants were tested in two conditions: differential, where each sample stimulus was paired with a specific outcome; and non-differential outcomes, where reinforcers were administered randomly. The results showed a significantly better face recognition in the differential outcomes condition relative to the non-differential in both experiments. Implications for memory training programs and future research are discussed.

Objective: Previous studies have demonstrated the benefit of the differential outcomes procedure (DOP) in human learning. In the present study we aimed to explore whether the DOP might also help to overcome the face recognition memory deficit commonly observed in Alzheimer’s disease (AD) patients. Method: A delayed matching-to-sample task was used. Participants were instructed to choose which of the 4 alternative faces (comparison stimuli) matched the previously seen face (sample stimulus). Either short (5 seconds) or long (25 seconds) delays were interposed between the sample and the comparison stimuli. In the differential outcomes condition each sample face was paired with its own outcome. In contrast, in the nondifferential condition, outcomes were randomly arranged. Results: The differential outcomes effect (DOE) was evident in the AD patients with both accuracy and latency data. That is, they showed a significantly better and faster delayed face recognition when differential outcomes were arranged. The analyses also revealed a significant main effect of delay; participants were slower in the 25 seconds condition than in the 5 seconds condition, but the difference was higher in the patients than in the controls. Conclusions: These findings demonstrate, to our knowledge for the first time, that face recognition memory in patients with Alzheimer is improved when differential outcomes are used and draw attention to the potential of this procedure as a therapeutic technique.

Although visual functions have been proposed to be enhanced in deaf individuals, empirical studies have not yet established clear evidence on this issue. The present study aimed to determine whether deaf children with diverse communication modes had superior visual memory and whether their performance was improved by the use of differential outcomes. Severely or profoundly deaf children who employed spoken Spanish, Spanish Sign Language (SSL), and both spoken Spanish and SSL modes of communication were tested in a delayed matching-to-sample task for visual working memory assessment. Hearing controls were used to compare performance. Participants were tested in two conditions, differential outcome and non-differential outcome conditions. Deaf groups with either oral or SSL modes of communication completed the task with less accuracy than bilingual and control hearing children. In addition, the performances of all groups improved through the use of differential outcomes.

Chlorpyrifos (CPF) is a broad spectrum organophosphate (OP) pesticide widely used in agriculture, industry and household. Several animal studies indicate emotional disturbances after CPF exposure, although the results are sometimes puzzling. Thus, both anxiolytic and anxiogenic effects of CPF have been reported in different animal models of anxiety [Sanchez-Amate MC, Flores P, Sanchez-Santed F. Effects of chlorpyrifos in the plus-maze model of anxiety. Behav Pharmacol 2001;12:285-92; Sanchez-Amate MC, Davila E, Canadas F, Flores P, Sanchez-Santed F. Chlorpyrifos shares stimulus properties with pentilenetetrazol as evaluated by and operant drug discrimination task. Neurotoxicology 2002;23:795-803; Lopez-Crespo G, Carvajal F, Flores P, Sanchez-Santed F, Sanchez-Amate MC. Time-course of biochemical and behavioural effects of a single high dose of chlorpyrifos. Neurotoxicology 2007;28:541-7]. On the other hand, other behavioural effects of CPF are time-dependent [Lopez-Crespo G, Carvajal F, Flores P, Sanchez-Santed F, Sanchez-Amate MC. Time-course of biochemical and behavioural effects of a single high dose of chlorpyrifos. Neurotoxicology 2007;28:541-7], raising the question that the effects of CPF could be task and post-administration time dependent. To test this hypothesis, three groups of rats were treated with a single high dose of CPF (250 mg/kg); one of the groups was tested on day 5 on the elevated plus-maze, to complete our previous study on day 2 [Sanchez-Amate MC, Flores P, Sanchez-Santed F. Effects of chlorpyrifos in the plus-maze model of anxiety. Behav Pharmacol 2001;12:285-92]. The remaining groups were tested on the elevated T-maze on days 2 and 5. CPF produced an increased open arm activity on the elevated plus-maze on day 5, an increased escape latency on the elevated T-maze on day 2 and an impaired inhibitory avoidance on day 5. Data are discussed taking together all studies carried out in our laboratory, confirming that CPF effects on emotional behaviour are dependent on both task contingencies and post-administration time.

Background: The differential outcomes procedure (DOP) has proved useful to improve discrimination learning in both animals and humans. Here we adapted DOP to assess its utility to overcome the memory loss commonly associated with normal aging.Methods: In a delayed matching-to-sample task, subjects were exposed to a man's face, and after a delay, they were required to decide if the previously seen face was within a set of six men's faces. For half the subjects, each sample face was paired with its own outcome (differential outcomes condition); outcomes were randomly arranged for the remaining half of subjects (non-differential condition). Either short (5 second) or long (30 second) delays were interposed between the sample and the comparison stimuli.Results: Results showed that relative to younger adults, older adults' performance decreased with the longer delay. However, the use of differential outcomes was able to reverse the detrimental effect of the increased delay in the elderly group, raising their performance to the level shown by younger adults.Conclusions: These findings demonstrate, for the first time, that DOP can help elderly people overcome their memory limitations, and they draw attention to the potential of this procedure as a therapeutic technique.

The purpose of this study was to determine the effects of different food-reinforcement schedules on plasma corticosterone (CORT), and its possible involvement in the acquisition and maintenance of schedule-induced polydipsia (SIP). In Experiment 1, three groups of rats were submitted to two different fixed-interval (FI) schedules with inter-food intervals of 30 and 120 s, and to a massed-feeding presentation for 40 days until SIP was well stabilized. In Experiment 2, six groups of rats were exposed to the same schedules, FI 30s and FI 120s, and to the massed-feeding condition, but no water bottles were presented. CORT levels were determined on Days 3 and 40. Results of Experiment 1 indicated that FI 30s schedule, but not FI 120s or the massed-feeding condition, induces excessive drinking from Day 3. Results in Experiment 2 indicated that CORT levels were similar for all the groups on Day 3. However, only animals on the FI 30s schedule did increase their CORT levels on Day 40, with no variation in the hormone in the other two conditions, FI 120s and massed-feeding presentations. The data are discussed in terms of the implications of these results for hypotheses of SIP as anxiolitic behavior.