The organization of words in the mental lexicon has been one of my main themes of research, dating back my
Ph.D. dissertation. My research in this field has focused around the concept of
morphological paradigms.
These are sets of words that share the same morphological constitutent
(e.g., roots, stems, etc.). In a number of studies we found that the
size of these paradigms (the
famiy size effect)
is a consistent predictor of lexical decision reaction times. This
observed across languages with very diffferent morphological
structures, including Dutch
(Moscoso del Prado, Deutsch, et al., 2005), Hebrew
(Moscoso del Prado, Deutsch, et al., 2005), and Finnish (
Moscoso del Prado, Bertram, et al., 2004).
Furthermore, non-native bilinguals are affected by these paradigms in
both languages they speak. Surprisingly, bilinguals are sensitive to
the morphological properties of words in their second language, even
when they are tested in settings and taks that do not involve their
second language. Paradigms in the second language interfere with the
subjects' first language processing, reflecting the large degree of
automaticity of morphological processes (
Dijkstra, Moscoso del Prado, et al., 2005).
In further research, in collaboration with several colleagues, we have
developed a parsimonious information-theoretical account of
morphological paradigms (
Moscoso del Prado, Kostić, & Baayen, 2004), that can also characterize the regularities between related paradigms (
Milin,
Filipović-Ɖurđević, & Moscoso del Prado, 2009).
Morphological relations are formed by a combination of formal
(orthographic and phonological) and semantic factors. In several
studies, we have documented the sensitivity of morphological effects to
semantic distinctions (
Moscoso del Prado, Bertram, et al., 2004,
Moscoso del Prado, Kostić, & Baayen, 2004,
Moscoso del Prado, Deutsch, et al., 2005,
Baayen & Moscoso del Prado, 2005).
Importantly, these semantic relations are part and parcel of the
morphological relation. Some current models of morphological processing
have claimed that it proceeds in two discrete stages, first accessing
the formal properties (i.e., "affix stripping"), and only then dealing
with the semantic details. However, joint consideration of the studies
published in the literature reveal that semantic effects happen indeed
very early (
Feldman, O'Connor, & Moscoso del Prado, 2009), which is in line with reports of very early semantic processing I observed in ERP studies (
Moscoso del Prado, Hauk, & Pulvermüller, 2006).
This has led to an interesting discussion on what type of model of
morphological processing does the literature actually support. In a
sequence of studies, in collaboration with
Laurie B. Feldman,
we have observed early semantic effects in morphological processing
across multiple languages, and a more detailed meta-analysis of the
literature reveals that these semantic component is indeed unavoidable.
The automatic semantic relations between morphologically related words
do not seem to fit well into affix-stripping models of morphology.
Rather, the system seems more like a messy system in which direct
"links" exists between morphologically related words, in line the the
current "
Word and Paradigm"
theories of morphology that are being developed in linguistics. From a
modelling perspective, this fits well into disributed connectionist
models of morphological processing. I have shown that distributed
connectionist models naturally give rise to the paradigmatic effects
reported above (see my
dissertation for a detailed model, and
Moscoso del Prado, Ernestus, & Baayen, 2004, for a more specific model). Currently, in collaboration with
Farrell Ackermann,
Jim Blevins, and
Rob Malouf, we are trying to extend the information theoretical model to provide a more general account of morphological relations.