Operant response rate can be viewed as bouts, periods of alternating engagement and disengagement with ongoing schedules of reinforcement. Relatively few studies have examined the role of force and effort on engagement bouts. Moreover, those examining effort have used switch closure devices to define the response. Switch closures tend to overestimate the effect of effort because increasing the force requirement excludes low-force responses that previously activated the switch. In the present study, we examined the effects of effort using a force transducer, which allows us to record criterion responses that meet the force requirement and subcriterion responses that do not. The current study was conducted using four male Sprague Dawley rats. Each rat was run through a series of four conditions, each with a different combination of variable interval schedules (VI 30s, VI 120s) and force requirements (5.6g, 32g). Log survivor analyses of bout structure showed that increased force requirements decreased the rate of bout initiations. Additionally, when log-survivor functions were computed using only criterion responses, shifts in the function were less extreme than when all measured responses were used; the latter finding suggests exclusion of "subcriterion" responses in prior work has overestimated the effects of force on bout structure

Transplants of fetal neural tissue survive and develop in lesion cavities produced in adult rats. The present experiment tested the effect of grafting fetal hippocampal or brainstem tissue on the ability of rats with hippocampal lesions to perform on a differential reinforcement of low response rate (DRL) operant schedule. The DRL interval was 20 s. Eighty-six percent of the hippocampal grafts and 69% of the brainstem grafts developed to maturity. Inspection of sections stained using a silver technique for axis cylinders or taken from rats in which the mature transplant had been injected with Fast blue, indicated that these grafts formed connections with the host brain. Consistent with previous reports, rats with hippocampal lesions were impaired in performance of the DRL task. Rats given fetal grafts of hippocampal tissue into the hippocampal lesion site on the day of lesion production were significantly better in performance of the DRL requirement than were lesion-only rats or rats receiving grafts of fetal brainstem tissue. The results of this study confirm that grafts of fetal brain tissue can both develop in a lesion site in an adult brain and ameliorate lesion-induced behavioral deficits.

No description available.

No description available.

Thesis (DPhil (Psychology))—University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Extensive research over the past 30 years has shown that reliable, sensitive, responsive and empathic care of the infant by the mother or mother-substitute in the early months facilitates the development of secure attachments in infants, and ultimately their healthy development towards competent adulthood and future relationships with others. This study analyses interviews with 17 mothers selected from an intervention proven successful by means of a randomized controlled trial. The intervention took place in Khayelitsha, a peri-urban settlement close to Cape Town, South Africa, and was delivered by previously untrained lay counsellors to at risk mothers and infants. Supervision and training of the counsellors was provided by the author. Mothers were purposively selected on the basis of being experienced by counsellors as easy, difficult to reach, young/immature mothers and HIV-positive mothers, and were interviewed by a clinically trained interviewer not involved in the project individually and in groups. Counsellors’ process notes, exploring the impact, relevance and meaning that the intervention had for the recipient mothers, as well as the supervisor’s notes were also used as data. The findings identify what changes mothers reported, their experiences of the intervention, cultural issues in the intervention, and mothers’ suggestions for modifications to the programme. The results are discussed in light of theories of change emerging from the literature on psychotherapy change research and research on community-based interventions. The study shows that though results of randomized controlled trials are necessary for policy planning, in-depth interrogation of the design and process issues at stake in complex community-based studies yield complementary data which are also important to consider. Finally, the study considers the implications of this understanding of process for the future dissemination of the training and application of this programme, as well as policy, research and funding challenges. / AFRIKAANSE OPSOMMING: Wydstrekkende, uitgebreide navorsing van die afgelope 30 jaar toon dat betroubare, sensitiewe, aandagtige en empatiese sorg vir die peuter deur die moeder of moeder-plaasvervanger, die vorming van veilige bindings, sowel as die uiteindelike gesonde ontwikkeling van bevoegde volwassenheid en toekomstige verhoudings met andere fasiliteer. Hierdie studie analiseer onderhoude met 17 moeders, gekies uit 'n intervensie wat bewys is deur middel van 'n ewekansige kontrole toetsing. Die intervensie het plaasgevind in Khayelitsha, 'n peri-stedelike nedersetting naby Kaapstad, Suid-Afrika, en is uitgevoer deur voorheen onopgeleide vrywilliger beraders wat moeders en peuters wat blootgestel is aan risiko bedien. Supervisie en opleiding van die beraders is deur die outeur voorsien. Moeders is vooraf uitgekies deur die beraders, volgens die criteria: maklik en moeilik bereikbaar, jong/onvolwasse moeders, en HIV positiewe status. 'n Klinies opgeleide onderhoudvoerder wat onbetrokke is by die res van die projek het met die moeders individueel en in groepskonteks onderhoude gevoer. Beraders se prosesnotas wat die impak, relevansie en betekenis van wat die invervensie vir die moeders ingehou het, sowel as die supervisor se notas is ook gebruik as data. Die bevindings is bespreek in die lig van veranderingsteorieë wat uit die literatuur oor psigoterapie veranderingsnavorsing, sowel as navorsing oor gemeenskapsgebaseerde intervensies vorendag gekom het. Die studie toon dat hoewel bevindings van ewekansige kontrole toetsing nodig is vir beleidsbeplanning, in-diepte ondersoek van die proses en ontwerp kwessies ter sake in komplekse gemeenskapsgebaseerde studies komplimentêre data lewer wat ook belangrik is om in ag te neem. Ten laaste oorweeg die studie die implikasies van hierdie ondersoek van proses vir toekomstige disseminasie van die opleiding en toepassing van hierdie program, sowel as beleid, navorsing en befondsings uitdagings.

A proposta do presente estudo é investigar a aquisição de comportamento verbal em uma pesquisa longitudinal com uma criança de desenvolvimento típico dos dezoito meses aos dois anos de idade, adotando como unidade de análise os operantes verbais propostos por Skinner (1957). O objetivo do trabalho é analisar as respostas verbais emitidas pela criança e pelo acompanhante em situações naturais em termos de operantes verbais e tentar identificar relações entre a emissão de operantes do acompanhante e da criança, de maneira a investigar possíveis padrões de interação na aquisição de comportamento verbal. Foram registradas e transcritas trinta e quatro sessões com duração média de quinze minutos por semana. Os dados foram analisados baseados em categorias criadas a partir dos operantes verbais propostos por Skinner (1957). Os resultados apontam um aumento abrupto na frequência acumulada da emissão das categorias de tatos, mandos, ecóicos e intraverbais da criança a partir dos vinte meses de idade. Esse aumento também ocorre simultaneamente na frequência acumulada da emissão das mesmas categorias do acompanhante. A categoria mais emitida pela criança foi a de tatos, enquanto que a categoria com mais emitida pelos acompanhantes foi a de mandos / The purpose of the present study is to investigate the acquisition of verbal behavior in a longitudinal research with a typical development child from eighteen months of age until two years old, adopting as unit of analysis Skinner´s (1957) verbal operants. The aim of the present work is to analyze verbal responses emitted by the child and the caretakers in a natural setting in terms of verbal operants and try to identify relations between the emission of operants by caretakers and the child, investigating possible interaction patterns in the acquisition of verbal behavior. Thirty four sessions of fifteen minutes of duration were registered per week and then transcript. Data were analyzed based upon categories created from Skinner´s verbal operants (1957). Results show a rapidly increase in the emission of tact, mand, echoic and intraverbal categories of the participant after twenty months of age. This increase also happened simultaneously in the emission of the same categories of the caretaker. The most emitted category of the child was the tacts, while the most emitted category by the caretaker was the mands

A proposta do presente estudo é investigar a aquisição de comportamento verbal em uma pesquisa longitudinal com uma criança de desenvolvimento típico dos dezoito meses aos dois anos de idade, adotando como unidade de análise os operantes verbais propostos por Skinner (1957). O objetivo do trabalho é analisar as respostas verbais emitidas pela criança e pelo acompanhante em situações naturais em termos de operantes verbais e tentar identificar relações entre a emissão de operantes do acompanhante e da criança, de maneira a investigar possíveis padrões de interação na aquisição de comportamento verbal. Foram registradas e transcritas trinta e quatro sessões com duração média de quinze minutos por semana. Os dados foram analisados baseados em categorias criadas a partir dos operantes verbais propostos por Skinner (1957). Os resultados apontam um aumento abrupto na frequência acumulada da emissão das categorias de tatos, mandos, ecóicos e intraverbais da criança a partir dos vinte meses de idade. Esse aumento também ocorre simultaneamente na frequência acumulada da emissão das mesmas categorias do acompanhante. A categoria mais emitida pela criança foi a de tatos, enquanto que a categoria com mais emitida pelos acompanhantes foi a de mandos / The purpose of the present study is to investigate the acquisition of verbal behavior in a longitudinal research with a typical development child from eighteen months of age until two years old, adopting as unit of analysis Skinner´s (1957) verbal operants. The aim of the present work is to analyze verbal responses emitted by the child and the caretakers in a natural setting in terms of verbal operants and try to identify relations between the emission of operants by caretakers and the child, investigating possible interaction patterns in the acquisition of verbal behavior. Thirty four sessions of fifteen minutes of duration were registered per week and then transcript. Data were analyzed based upon categories created from Skinner´s verbal operants (1957). Results show a rapidly increase in the emission of tact, mand, echoic and intraverbal categories of the participant after twenty months of age. This increase also happened simultaneously in the emission of the same categories of the caretaker. The most emitted category of the child was the tacts, while the most emitted category by the caretaker was the mands

Thesis (Ph. D.)--University of California, San Diego, 2009. / Title from first page of PDF file (viewed February 11, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 681-712).

No description available.

Thesis (MA (Psychology))--University of Stellenbosch, 2006. / The study attempted to gain insight into the behavioural response to termination/ graduation of a group of ten female graduates from a community intervention programme. The participants, aged between eleven and fourteen years and predominantly from low socio-economic backgrounds, attended the Usiko Girls Youth Community Programme. The eighteen month programme aimed to facilitate their transition from girlhood to womanhood. To this end, the program was conceptualized as having various components including, but not limited to, Initiation, Life skills training, Cultural activities, Camps, and graduation. After the graduation ceremony, which culminated in the termination of the programme for these participants, they returned to the programme, stating different reasons for doing so. A single group, post-test design, utilizing a structured interview was employed with the main focus being the graduation and termination component, to help understand this phenomenon. Thematic analysis and descriptive statistics were used to analyze the data. Results suggest that the participant’s identification with the programme made it difficult for some to terminate.