Stimulus control of differential-reinforcement-of-low-rate responding

Five pigeons were given single-stimulus training on an 8-sec differential-reinforcement-of-low-rate schedule followed by steady-state generalization training using 12 wavelength stimuli. Three birds had a high percentage of reinforced responses on the training schedule and flat generalization gradients of total responses. The birds with fewer reinforced responses had much steeper generalization gradients. Generalization gradients plotted as a function of both stimulus wavelength and interresponse time showed that for most birds, stimulus control was restricted to responses with long interresponse times. Responses with very short interresponse times were not under stimulus control and there was some evidence of inhibitory control of short interresponse times. Interresponse-times-per-opportunity functions, plotted as a function of stimulus wavelength, showed that stimulus wavelength controlled the temporal distribution of responses, rather than the overall rate of response. The data indicate that the differential-reinforcement-of-low-rate schedule generates several response categories that are controlled in different ways by wavelength and time-correlated stimuli, and that averaging responses regardless of interresponse-time length obscures this control.     

Do wild New Caledonian crows (<Emphasis Type="Italic">Corvus moneduloides</Emphasis>) attend to the functional properties of their tools?

New Caledonian crows are the most proficient non-hominin tool manufacturers but the cognition behind their remarkable skills remains largely unknown. Here we investigate if they attend to the functional properties of the tools that they routinely use in the wild. Pandanus tools have natural barbs along one edge that enable them to function as hooking implements when the barbs face backwards from the working tip. In experiment 1 we presented eight crows with either a non-functional (‘upside-down’) or a functional pandanus tool in a baited hole. Four of the crows never flipped the tools. The behaviour of the four flipping birds suggested that they had a strategy of flipping a tool when it was not working. Observations of two of the eight crows picking up pandanus tools at feeding tables in the wild supported the lack of attention to barb direction. In experiment 2 we gave six of the eight crows a choice of either a barbed or a barbless pandanus tool. Five of the crows chose tools at random, which further supported the findings in experiment 1 that the crows paid little or no attention to the barbs. In contrast, a third experiment found that seven out of eight crows flipped non-functional stick tools significantly more than functional ones. Our findings indicate that the crows do not consistently attend to the presence or orientation of barbs on pandanus tools. Successful pandanus tool use in the wild seems to rely on behavioural strategies formed through associative learning, including procedural knowledge about the sequence of operations required to make a successful pandanus tool. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Young Children’s Physiological Reactivity during Memory Recall: Associations with Posttraumatic Stress and Parent Physiological Synchrony

Autonomic reactivity is implicated in stress response and social engagement – both key components of posttraumatic stress disorder (PTSD) – but few studies have examined autonomic reactivity in pediatric samples, and no known studies have examined physiological synchrony among children with PTSD and caregivers. In a sample of 247 young children (94 girls, 153 boys), most (85%) of whom had exposure to trauma and 40% who met criteria for PTSD, we examined children’s patterns of respiratory sinus arrhythmia (RSA) at baseline and in response to a memory recall task, as well as correspondence between parents’ and children’s RSA. Children with PTSD demonstrated significantly higher reactivity than other groups during their recollection of a traumatic memory, but not during other memory tasks. Regarding synchrony, caregivers’ and children’s RSA were more significantly and positively correlated during the trauma recall task among children who had had exposure to a potentially traumatic event but did not meet PTSD criteria, suggesting physiological synchrony may be protective in contexts of trauma. Overall, findings demonstrate physiological reactivity differences among young children with PTSD. While more work is needed to understand the meaning of parent-child physiological synchrony, these data suggest that children’s psychopathology is associated with physiological synchrony processes among young children with exposure to trauma.     

Engineering interaction: Structural change,locus of identification,and the formation and maintenance of cross-unit ties

Cross-unit ties–relationships that facilitate discretionary information sharing between individuals from different business units–offer a range of organizational benefits. Scholars argue that organizations can promote cross-unit ties by: (a) formally bringing together individuals from different business units into structural links (e.g., cross-unit strategic committees) to encourage the formation of new cross unit ties and, (b) transferring individuals across units, which can increase cross-unit interaction when ties to the prior unit are maintained. This study considers the notion that the success of these formal interventions in fostering cross-unit interaction is contingent on identification with the local unit relative to identification with the broader organization. Specifically, we propose that structural links are more likely to foster cross-unit ties when organizational identification is high and unit identification is low. In contrast, lateral transfers are more likely to result in cross-unit ties when both organizational identification and unit identification are high. We find general support for these propositions in data obtained from a sample of senior leaders of a Fortune 200 agribusiness company before and after a restructuring designed to stimulate cross-unit information sharing. Our model and results make important contributions to our understanding of the relationship between formal and informal structure and reconcile conflicting views regarding the moderating effect of unit identification on intergroup relations.     

An Exploration of Family Problem-Solving and Affective Involvement as Moderators Between Disease Severity and Depressive Symptoms in Adolescents with Inflammatory Bowel Disease

Little is known about how family functioning relates to psychosocial functioning of youth with inflammatory bowel disease (IBD). The study aim was to examine family problem solving and affective involvement as moderators between adolescent disease severity and depressive symptoms. Participants were 122 adolescents with IBD and their parents. Measures included self-reported and parent-reported adolescent depressive symptoms, parent-reported family functioning, and physician-completed measures of disease severity. Disease severity was a significant predictor of adolescent-reported depressive symptoms, but not parent-reported adolescent depressive symptoms. Family affective involvement significantly predicted parent-reported adolescent depressive symptoms, while family problem-solving significantly predicted adolescent self-report of depressive symptoms. Neither affective involvement nor problem-solving served as moderators. Family affective involvement may play an important role in adolescent emotional functioning but may not moderate the effect of disease severity on depressive symptoms. Research should continue to examine effects of family functioning on youth emotional functioning and include a sample with a wider range of disease severity to determine if interventions aimed to enhance family functioning are warranted.