Modeling core affect trajectories with diffusion models
Zita Oravecz PhD
Project at: Department of Psychology, K.U.Leuven, Belgium
Supervisors: Prof. dr Francis Tuerlinckx and prof. dr Paul De Boeck
Project running from: 1 November 2005 – 1 November 2009
Core affect is the heart of any emotional experience. It is a continuously present but ever changing affective state, not directed towards an object. Core affect is characterized by two dimensions: Activation (vs. deactivation) and Pleasantness (vs. unpleasantness). At any given point in time, a person occupies a certain position in this two-dimensional space and throughout time, his or her position changes depending on external (i.e., outside the person) or internal (i.e., inside the person) factors. With this research we want to model the trajectories of people in this space with a particular class of stochastic models, called diffusion models. In a first stage of the project we are going to explore the possibilities of diffusion processes as models for the trajectory of a single person. The basic model for the trajectories is the Ornstein-Uhlenbeck diffusion process, a time homogeneous continuous-time Markov model with a continuous state space. In the next step, a random-effects extension will be formulated so that the model can be used for the data of several unrelated persons. Because of the fact that many parameters in the individual switching Ornstein-Uhlenbeck process can vary across persons, there will be rather large algorithmic challenges. Finally, a model consisting of coupled system of processes will be developed to explain the trajectories of partners in the core affect space.
Date of defence: 25 November 2009
Title of thesis: Analyzing core affect changes with the hierarchical Ornstein-Uhlenbeck process model