The relation of multiple-schedule behavioral contrast to deprivation,time in session,and within-session changes in responding

Pigeons' keypecking was reinforced by food on baseline schedules of multiple variable interval (VI) x VI x and on contrast schedules of multiple VI x VI y. Deprivation of food was varied by maintaining subjects at 75%, 85%, and 95% (+/- 2%) of their free-feeding weights. Positive and negative behavioral contrast were observed. The size of the contrast was not systematically altered by changes in deprivation. Positive and negative contrast were both larger later in the session than they were earlier. Within-session decreases in responding were steeper for the baseline than for the contrast schedules for positive contrast. Within-session decreases were steeper for the contrast than for the baseline schedules for negative contrast. These results were predicted by the idea that different amounts of habituation to the reinforcer during the baseline and contrast schedules contribute to behavioral contrast. The results show that contrast occurs under conditions that reduce the effect of the following component. The results support the assumption that positive and negative contrast are produced by symmetrical theoretical variables.     

Impact of brief or extended extinction of a taste aversion on inhibitory associations: Evidence from summation,retardation, and preference tests

In five conditioned taste aversion experiments with rats, summation, retardation, and preference tests were used to assess the effects of extinguishing a conditioned saccharin aversion for three or nine trials. In Experiment 1, a summation test showed that saccharin aversion extinguished over nine trials reduced the aversion to a merely conditioned flavor (vinegar), whereas three saccharin extinction trials did not subsequently influence the vinegar aversion. Experiment 2 clarified that result, with unpaired controls equated on flavor exposure prior to testing; the results with those controls suggested that the flavor extinguished for nine trials produced generalization decrement during testing. In Experiment 3, the saccharin aversion reconditioned slowly after nine extinction trials, but not after three. Those results suggested the development of latent inhibition after more than three extinction trials. Preference tests comparing saccharin consumption with a concurrently available fluid (water in Experiment 4, saline in Experiment 5) showed that the preference for saccharin was greater after nine extinction trials than after three. However, saccharin preference after nine extinction trials was not greater, as compared with that for either latent inhibition controls (Experiments 4 and 5) or a control given equated exposures to saccharin and trained to drink saline at a high rate prior to testing (Experiment 5). Concerns about whether conditioned inhibition has been demonstrated in any flavor aversion procedure are discussed. Our findings help explain both successes and failures in demonstrating postextinction conditioned response recovery effects reported in the conditioned taste aversion literature, and they can be explained using a memory interference account.     

Role strain,engagement and academic achievement in early adolescence

The present study was designed to investigate the relationships between role strains following the transition to secondary school and academic achievement. Academic engagement was hypothesized to mediate between role strain and achievement. The sample consisted of 749 students in their first year of secondary school. Four types of role strain were investigated: parent, teacher, school and peer. Parent and teacher role strains appeared to be negatively associated with academic achievement, as mediated through academic engagement. Parent and school role strain were directly and negatively associated with achievement. Results are discussed in the light of parenting practices and the developmental mismatch hypothesis.     

When screens replace backyards: strategies to connect digital-media-oriented young people to nature

Abstract

Children’s connection to nature (CTN) is declining with each generation, a concerning trend given that CTN is positively linked to wellbeing and environmentalism. A primary cause of this decline is that twenty-first-century youth engage with screens for several hours each day, which to a large extent replaces nature-based play. Researchers have proposed that this change represents a transition in human orientation, particularly in Westernized societies, from nature (biophilia) to digital media (videophilia). Interventions promoting nature-based play must acknowledge digital-media use as a competing leisure pursuit, but the literature presents little guidance for designing programs that will attract young people who are more oriented toward digital media than nature. Drawing on a wide breadth of research, we address this gap through (1) exploring the implications of videophilia for nature-based programming and (2) summarizing recommendations from a narrative literature review for designing interventions that appeal to digital-media-oriented youth.     

What Can Be Learned from Something's Not Being Named

A new word-learning phenomenon is demonstrated and a new word-learning principle is proposed to account for it. In Study 1, 60 3-year-olds were shown a pair of objects and heard a novel label used repeatedly for one, but not for the other. In a forced-choice test of generalization of the label, the latter object was selected less often by the children than one that had not been present during training. This so-called Nominal Passover Effect was the same whether the speaker had completely ignored the comparison object during training or had referred to it with pronouns. The performance of a no-word control group ( N = 24) indicated that the effect was not due to a preference for the less exposed of the two choice objects. The effect is consistent with the Exhaustive Reference Principle, which stipulates that whenever a new generic word is used to name something, expect it to be extended to all entities in a situation that the speaker perceives and believes to be exemplars of the name. In Study 2 ( N = 48), the Nominal Passover Effect was replicated with 3 new sets of objects and with training language that contained only indefinite forms of reference. The passover experience was often sufficient to counteract children's tendency to generalize a novel label on the basis of perceptual similarity. The passover effect was not evident in free-choice name generalization tests in either study.     

师生冲突的概念界定与分类探究——基于刘易斯·科塞的冲突分类理论

论文通过借鉴和辨析社会学理论中的冲突概念,对师生冲突概念作出界定。根据美国当代社会学家刘易斯·科塞的冲突分类理论,对学校师生冲突进行分类研究。在此基础上提出了三个观点:学校师生冲突的多数属于非现实性冲突;师生结构由紧密走向松散是师生冲突增多的重要原因;师生冲突具有一定的正面功能。     

Land degradation,government subsidy,and smallholders’ conservation decision: the case of the loess plateau in China

Land degradation is one of the severe environmental problems in China. In order to combat land degradation, a soil conservation program was introduced since 2000 to reduce soil erosion by converting slope-cultivated land into forestry and pasture. This paper represents the first systematic attempt to investigate the impact of the soil conservation program on land degradation in the loess plateau. The results indicate that the soil conservation program to convert slope fields into forest or pasture is an effective way to combat soil erosion. However, a subsidy that is higher than profit of land use activity of slope fields before their conversion into forest and pasture is needed to encourage farmers to join the conservation program. A policy measure to encourage and assist farmers to develop sedentary livestock by using crops produced from fields as well as fodder and forage grass from the converted slope fields might contribute to combat soil erosion. Increase in off-farm job opportunities may encourage households to reduce cultivation in slope fields. That implies a policy measure to encourage rural urbanization might contribute to combat soil erosion.     

How infants use vision for grasping objects

The role of vision was examined as infants prepared to grasp horizontally and vertically oriented rods. Hand orientation was measured prior to contact to determine if infants differentially oriented their hands relative to the object's orientation. Infants reached for rods under different lighting conditions. Three experiments are reported in which (1) sight of the hand was removed (N = 12), (2) sight of the object was removed near the end of the reach (N = 40, including 10 adults), and (3) sight of the object was removed prior to reach onset (N = 9). Infants differentially oriented their hand to a similar extent regardless of lighting condition and similar to control conditions in which they could see the rod and hand throughout the reach. In preparation for reaching, infants may use the current sight of the object's orientation, or the memory of it, to orient the hand for grasping; sight of the hand had no effect on hand orientation.     

To tag or not to tag? How to support organizing and classifying bookmarks from the Web (¿Con etiquetas o sin etiquetas? Cómo asistir en la organización y clasificación de los marcadores de páginas Web) (¿Con etiquetas o sin etiquetas? Cómo asistir en la organización y clasificación de los marcadores de páginas Web)

ABSTRACT

When searching for information on the Internet, it can be stored in a bookmarking system. The ability to organize this information in such a system depends on one’s own prior knowledge to create an appropriate classification scheme. Providing a classification system for bookmarks might support people with low prior knowledge. Even though different bookmarking systems exist, hierarchical menus and tagging are being most widely used. In the current exploratory study with 95 ninth-grade students, a 2 × 2 between-subjects design was used to investigate the influence of providing classification support (or not) for either a tagging or a hierarchical system. Results showed that despite the low familiarity with tagging systems, using a hierarchical system is not necessarily a better approach than using a tagging system to organize previously found information. Rather, a tagging system seems to yield storage of fewer but higher-quality information sources. The most important conclusion is that, despite the low familiarity with tagging systems, using a hierarchical system was not beneficial over using a tagging system to organize previously found information.