Béhaviorisme | EPFL Graph Search

Le béhaviorisme ou comportementalisme est un paradigme de la psychologie scientifique selon lequel le comportement observable est essentiellement conditionné soit par les mécanismes de réponse réflexe à un stimulus donné, soit par l'histoire des interactions de l'individu avec son environnement, notamment les punitions et renforcements par le passé. L'approche béhavioriste vise à mettre au jour des relations statistiquement significatives entre les variables de l'environnement et les mesures du comportement étudié sans faire appel au psychisme comme mécanisme explicatif. Le béhaviorisme émerge à la fin du et au début du en réaction à la difficulté des courants mentalistes, subjectivistes et introspectifs à produire des énoncés scientifiques empiriquement testables. Après avoir exercé une influence très forte sur la recherche en psychologie en Amérique du Nord et en Europe, le béhaviorisme, en particulier dans sa forme radicale défendue par des chercheurs comme B. F. Skinner qui cherc

La modélisation des facteurs humains dans la gestion de projets

Roland Sauter

During the past years, project management has been rapidly spreading out into the various domains of human endeavor; project management is becoming the most promising form of management in a changing world. This development increased drastically the need for training programs for project managers, and the main challenge of those training programs is their behavioral aspect, the training of interpersonal skills. The aim of our work is to create a model of the human factors in project management, in order to build a training simulator which would integrate the technical expertise and the human factors. In order to establish a list of the relevant human factors in project management, we conducted a first survey among one hundred project managers. The findings of this first survey allowed us to work out a certain number of hypotheses, which were tested in a second survey on a larger sample of project managers (700). The construction of our model has been done with a precise goal: a training simulator – that's why we could simplify the problems in several ways, especially regarding the circular interactions of some variables in the model. The data gathered in the survey were used to determine the parameters of the model. The construction of such a model is the first specificity of our work. Then we developed a full-scale training simulator for project managers, and we implemented our model of the human factors in this simulator. The simulator is centered on the planing and execution phases of a project. A simple, easy-to-use interface allows the user to visualize the project status, to make adequate decisions and to see the effect of those decisions on the project and on the evolution of the human factors immediately. The integration of the technical tasks and the human factors into a simulator is the second specificity of our work. This simulator has been in use since the beginning of 1995, and 200 project managers have been trained since then. A survey was conducted among the trainees: it showed the high efficiency of this type of training in a virtual world, the very high motivation of the trainees and a high learning effect on the behavioral level.

EPFL1996

Rat model: neural substrates of the battered woman syndrome

Xavier Fontana

This study is part of a long term study on a male rat model of peripubertal stress in the Laboratory of Behavioural Genetics that shows increase aggressive behaviours against their partners. We are using here these rats in order to create a female rat model victim of Intimate Partner Violence during pregnancy and to study the generalisation of fear to all male, that is a symptom of this type of aggression, through behavioural analysis, serotonergic cell activation of the Dorsal Raphe Nucleus (DRN) and activation of other regions known to interact with the DRN such as Periaqueductal Gray (PAG) and Amygdala. This study also reveal an in-utero transmission of aggressive behaviours to the offspring of peripubertally stressed male. Our findings suggest that our model show a generalisation of fear that depends on the type of aggression experienced. This generalisation is mediated by an increase of activation of serotonergic cells of the DRN as well as a general disruption of pattern of activation at the basal level. Interestingly, our results do not show a clear direct link between activation of DRN, PAG and Amygdala during generalisation of fear

2010

Etude par STM de la déposition d'agrégats d'or sur TiO2 et mesure de l'émission électronique secondaire induite par l'impact d'agrégats sur une surface

Pierre Convers

This thesis work focuses on impact and diffusion processes as well as equilibrium positions of a metal deposited on a surface. The metal is deposited in the form of clusters containing n atoms in a controlled way. Gold or silver clusters cations (Au+n and Ag+n ) are used. Their size (n ∈ [1, 9]), charge state and deposition energy (E = 10 - 4500 eV) are well defined. The surface being at room temperature during the deposition, can be annealed and transferred in a scanning tunnelling microscope (STM) after deposition. The variable temperature microscope was developed during this thesis. The approach of the tip is carried out by an axial motor, which renders the microscope very stable. The first part of this work treats of the evolution of gold deposited on a TiO2(110) surface. Position and size of gold islands created by cluster or atomic depositions are determined by STM. Compared to atomic deposition at the same energy (10 < E < 100 eV), the cluster deposition produces smaller islands with a large islands density after annealing at 800 K. Regardless the deposition conditions, gold atoms diffuse on the surface already at 300 K. The impact energy is the key parameter to reduce the diffusion by cluster or atomic implantation or defect creation. Upon a high energy deposition, part of the deposited gold is invisible to the STM. The fate of these gold atoms is unclear : they are either buried under the surface or ejected in vacuum at the impact. The control of the islands size should permit the creation of a stable system with an optimum catalytic activity (i. e. CO combustion). Research groups have shown that this activity is strongly influenced by the islands size. It is equal to zero if the diameter is greater than 5 nm. The second part of this work is devoted to the electron emission γ induced by the impact of silver clusters Ag+n on a Pt and HOPG surface. Measurements are made by varying the impact energy (and so the speed v) of size-selected clusters on a defined surface. Impact velocity ranges from 104 to 105 m/s, which is lower than the classical threshold. Nevertheless every cluster size produces an electron emission. A potential emission (γ(v=0) ≠ 0) is observed for the monomer on both surfaces, which is caused by excited ions in a metastable state. The γ(v) curves are increasing, and no mesurable oscillation are observed. This does not confirm earlier work by Meiwes-Broer et al. These authors found oscillations in γ on similar systems relating them to the electronic structure of the clusters and the surface. A model based on heating of the electron gas is developed. This model gives good agreements with the γ(v) curves. The electronic temperature is estimated to 3000-8000 K. Similar behavior on both surfaces (Pt and HOPG) depending of the cluster size is shown. This behavior is probably related to the geometrical structure of the clusters. Finally, a more pronounced molecular effect is observed for the HOPG : the number of electrons emitted by the impact of a Ag+n is up to 7 times higher than the number of electrons emitted by impacts of n independent atoms. This value is smaller than 2 for the Pt surface.

EPFL2005