Modeling Lexical Access in Comprehension
Summary
This thesis investigates lexical access by applying information-theoretic measures to
quantify the complexity of verb processing in comprehension. It examines the effects
of two key factors: Information (I), representing the complexity of an individual word
form, and Entropy (H), representing the probabilistic variability within a word’s inflectional
family. Using existing experimental data from neuro-typical participants and individuals
with aphasia, the study employs both linear mixed-effects models (LMEMs) and non-linear
sigmoid-based mixed-effects models to analyze the relationship between these factors and
reaction times.
The research addresses two main questions: to what extent do I and H affect lexical
access, and how do these effects differ between neuro-typical and aphasic populations. The
findings indicate that I and H have opposing effects on processing times, with I having an
inhibitory effect and H having a facilitatory one. The models also reveal that the effect
of H is significantly stronger than the effect of I and that this difference is even more
pronounced in participants with aphasia. The non-linear models support these findings
while also providing a more realistic framework that accounts for the bounded nature of
human processing capacity. This work provides a deeper understanding of the "reduced
ability" in aphasia, suggesting that it involves not just a general slowing but a specific
alteration in how the cognitive system processes different types of information load during
word retrieval.