| The current project investigated the right hemisphere role in new word and meaning acquisition, and examined whether this is modulated by an individual's reading skill as measured by Nelson-Denny Reading Test. Beeman proposed that the right hemisphere has a coarse coding style, and is better able to integrate weak semantic relations in contrast to more fine semantic coding within the left hemisphere (Beeman & Chiarello, 1998), A coarse coding style may help in learning the meanings of new words (Ince & Christman, 2002). In addition, a right hemisphere advantage in learning new words may be influenced by reading skill (see Perfetti, Wlotko, & Hart, 2005). The current project also examined quantitative versus qualitative hypotheses for lateralization of word acquisition; the former emphasizes the amount of experience with words, while qualitative hypothesis emphasizes brain maturation state. Two experiments were included in the current project. The first experiment presented the new words and meanings either 2 or 8 times, thereby varying the number of semantic learning contexts. The second experiment added an English condition. Forced choice recognition tested learning of new words, followed by the critical divided visual field semantic relatedness judgment test. It was predicted that skilled readers would utilize the most appropriate hemispheric strategy, resulting in a left hemisphere advantage for more experienced words, and right hemisphere advantage for less experienced words. Less-skilled readers were predicted to have less hemispheric asymmetry in the more experienced condition. The combined experiment data suggest an advantage for rvf/LH for English words. The top 25% of comprehenders had lvf/RH performance that is much more efficient than the bottom 25% of comprehenders. This was not observed when the groups were divided by median split. In Experiment 2 the English condition had a robust rvf/LH advantage, which was not observed in the 2x and 8x condition. This may be taken to support coarse-fine coding hypotheses. It is concluded that greatly increased experience with words is crucial for rvf/LH advantages to emerge, superior comprehenders have more efficient RH processing, and that left-lateralization occurs through increased experience with individual words (i.e., the quantitative hypothesis is supported). |
