University of Amsterdam
Psychological Methodology
Department of Psychology, FMG

Supervisors:
– prof.dr. D. Borsboom (University of Amsterdam)
– dr. L.J. Waldorp (University of Amsterdam)
– dr. J.W. Romeijn (University of Groningen)
– prof.dr. H.L.J. Van der Maas (University of Amsterdam)

On April 23rd 2014 Rogier Kievit defended his thesis entiteld

Turtles all the way down? Psychometric approaches to the reduction problem

Summary
The question of how different explanatory levels in scientific inquiry are related to each other is known as the reduction problem. This thesis focuses on a specific domain of this question, namely how we should relate brains to (psychological) behaviour. The central position of this thesis is that this question is ultimately a measurement problem. That is, in order to understand the relationship between brains and minds,
we need to formulate measurement models that can relate observable variables (e.g. response times, brain activity, brain structure) to the underlying constructs we are interested in (e.g. memory capacity, intelligence or personality differences). Moreover, in the case of relating brains to behaviour, theories from philosophy of mind can be translated into such measurement models, thereby guiding empirical inquiry and simultaneously providing an empirical test of philosophical theories. Further extensions of these ideas focus on the application of representational geometry, whereby the structure of neural and behavioural patterns are used to relate brain and behaviour, and the examination of cases where inferences across explanatory levels goes awry (known as Simpson’s Paradox). Based on empirical applications in several domains it is concluded that supervenience theory, which suggests a fundamentally asymmetrical relationship between brain and mind, is most in line both with theoretical considerations and empirical data.

Project

Statistical models for reductive theories
This project reformulates the reduction problem as measurement problem, by focusing on the question how we should combine physical and psychological indicators in a single measurement structure. In the first subproject, different positions that have been articulated in the philosophy of mind, such as identity theory and supervenience, are translated into different psychometric models. In the second subproject, these models are applied to existing datasets involving a) the relation between IQ and physical properties of the brain (e.g., brain volume), b) the relation between EEG measures of speed of processing and IQ,and c) the relation between anatomical differences in the brain and different kinds of synesthetic experience. In the third subproject, the prospects for a reductive explanation of inter-individual differences on the basis of intra-individual processes is evaluated according to theoretical insights taken from the philosophical literature on reduction.

This project was financed by the University of Amsterdam.