Age of acquistion and phonology in lexical processing

The work presented in the current thesis was aimed at
identifying the exact locus of the age of acquisition (AoA) effect
within the systems responsible for word and picture processing.
Chapter One reviews some of the current influential models of word
and picture production and discusses the effects that AoA (and
frequency) have upon these processes. Current theories of AoA are
also discussed. Chapters Two and Three assess the locus of the AoA
effect in the word naming task. The results of these experiments lead
to the conclusion that AoA (and frequency) exert their effects in the
connections between orthography and phonology in single word
naming. Chapter Four then tested the alternative claim that AoA
affects the level of phonological output processing by investigating
the AoA effect in a phonological segmentation task and by relating
the size of the AoA effect in this task and in a word naming task to
individual differences in phonological skill. The results of this
comparison demonstrate that AoA is unrelated to explicit
phonological processing. Chapter Six then investigated the effect of
AoA (and other variables) in the picture naming task by relating
aphasic patient's level of impairment to the variables that affect their
picture naming performance. The results of this study suggest that
AoA influences the strength of the connections between semantics
and phonology in picture naming. The present thesis concludes that
AoA influences the strength of the connections between input
(orthography and semantics) and phonological output. The final
Chapter discusses the implications of the present results for current
theories of AoA and for models of word and picture production.