Examination of the Psychological Meaning of the Alpha Parameter of the Lévy-Flight Model

• Applicant: Professorin Dr. Veronika Lerche
• Subject Area: General, Cognitive and Mathematical Psychology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 544295316

In this project, we examine the psychological meaning of the alpha-parameter of the Lévy-flight model (LFM). The LFM has recently been introduced to the field of mathematical psychology as a promising alternative to the classical diffusion model (DM). Like the DM, the LFM is applied to data of response time tasks with two response options (e.g., brightness discrimination or lexical decision tasks) to illuminate the different distinct processes underlying binary choice behavior. In contrast to the DM, the LFM allows the estimation of an additional parameter, namely, the alpha-parameter. The alpha-parameter specifies the noise distribution in such a way that jumps (i.e., sudden major changes) in information accumulation can now also be represented. Whereas the main parameters of the DM (i.e., drift rate, threshold separation, starting point, and nondecision time) have already been examined in terms of their validity in numerous studies, the meaning of the alpha-parameter has not yet been systematically addressed. We propose three different possible interpretations of the alpha-parameter. Depending on the context of the task (e.g., perceived time pressure), alpha might be considered a measure of (a) guessing, (b) strategy instability, or (c) differential weighting of information. These possible interpretations will be examined in this project by means of a variety of experimental studies and a comprehensive parameter recovery study.

• DFG Programme: Research Grants