Introduction

1. Newly-Learned Stimuli: The Effects on Lateralized Lexical DecisionTravellia Tjokro & Christine Chiarello University of California, Riverside Fig. 2 Introduction Fig. 1A & 1B • * It has been proposed that the two hemispheres have different styles of coding information (Beeman, 1998). • Right hemisphere - coarse coding style. • Advantage: Better activation of distant semantic relations. • Disadvantage: Poor performance on selection of one, precise response. • Left hemisphere - fine coding style. • Advantage: Better performance when one, precise response need to be selected. • Disadvantage: Distant semantic relations are not maintained. • Lateralized lexical decision studies have found: • Nonwords showed no hemispheric asymmetry (e.g.: Leiber, 1976; Chiarello, Senehi, & Soulier, 1986; Measso & Zaidel, 1990). • Word stimuli showed rvf/LH advantages (e.g.: Leiber, 1976; Weems & Zaidel, 2005). • Unfamiliar & newly-learned words showed lvf/RH advantages (e.g.: Ince & Christman, 2002). • Current studies required the participants to learn new words, and then the participants were tested on a version of lateralized lexical decision task in order to investigate whether the right hemisphere was advantaged or processing the newly-learned words. • According to the differential hemispheric coding style proposition, newly-learned words would be advantaged in the right hemisphere because coarse coding allows more semantic connections to be made. • Exp. 2 was conducted for the following reasons: • To obtain a more stringent measure of a participant’s learning of the new words by incorporating a forced choice recognition test. • To take into account the advantageous effects of memory consolidation by conducting the experiment over 2 days. • To obtain a more sensitive measure of a new word’s establishment in a participant’s lexicon by utilizing a semantic priming paradigm. • RT of Related and Unrelated Prime Conditions • Prime conditions did not significantly differ from one another (p = 0.2). • Visual field performance differed significantly (p = 0.001). - rvf/LH was faster than lvf/RH. • Interaction between visual field and prime conditions was not significant (p = 0.4). Method Exp. 2 (2-Day) • PARTICIPANTS: • 24 male, 24 female right-handed native English speakers • TASKS: • Encoding Phase (Day 1)- similar to Exp. 1, without orthographically-based encoding • Forced-choice (Day 1 & 2). • What is a pajama worn by a baby dwarf? SURK vs. LILE (both choices were studied before). • Lateralized lexical decision with semantic priming (Day 2). • Targets: Semantically-encoded nonwords & nonwords never before seen. • Primes: English words with related and unrelated meanings (e.g.: Related prime for SURK is ROBE, Unrelated prime is CHICK). • Participants responded “Yes” to the newly-learned words, and “No” to never before seen words. Conclusions Method Exp. 1 • The finding that the left visual field had a significant priming advantage compared to the right visual field may point to the possibility that lvf/RH has an advantage in newly-learned materials. • The absence of an lvf/RH advantage in Exp. 1 and the presence of lvf/RH advantage in priming in Exp. 2 suggests the possibility that the RH may be more likely to be advantaged when the newly-learned stimuli are presented along with more familiar primes, which may serve as scaffolds for the newly-learned stimuli. • The right hemisphere may have a functional role in new word acquisition. The use of semantic priming seems to be a promising technique to gauge its involvement. • PARTICIPANTS: • 24 male, 24 female right-handed native English speakers • TASKS: • Encoding Phase (semantically & orthographically-based encoding). • SURK is a pajama worn by a baby dwarf. • Is SURK worn by a grandfather? - semantic • Is there a vowel in SURK? - orthographic • Lateralized lexical decision. • English words, semantically-encoded nonwords, orthographically-encoded nonwords, never before seen nonwords. • Participants responded by pressing “Yes” for English words, and “No” to all others. References Results Exp. 2 Results Exp. 1 • Beeman, M. (1998). Coarse semantic coding and discourse comprehension. In M. Beeman & C. Chiarello (Eds.), Right hemisphere language comprehension (pp. 255-284). Mahwah, NJ: Lawrence Erlbaum Associates. • Chiarello, C., Senehi, J., & Soulier, M. (1986). Viewing conditions and hemisphere asymmetry for the lexical decision. Neuropsychologia, 24(4), 521-529. • Ince, E., & Christman, S. D. (2002). Semantic representations of word meanings by the cerebral hemispheres. Brain and Language, 80, 393-420. • Leiber, L. (1976). Lexical decisions in the right and left cerebral hemispheres. Brain and Language, 3, 443-450. • Weems, S. A., & Zaidel, E. (2005). Repetition priming within and between the two cerebral hemispheres. Brain and Language, 93, 298-307. EXP. 2 • Accuracy of Related and Unrelated Prime Conditions • Prime conditions did not significantly differ from one another (p = 0.3). • Visual field performance differed significantly (p = 0.002). - rvf/LH is more accurate than lvf/RH. • Interaction between visual field and prime conditions was significant (p = 0.04) - See Fig. 2. EXP. 1 Lateralized lexical decision Phase: • As seen in Fig. 1A&B, all stimuli, including the newly-learned words, produced rvf/LH advantages. Acknowledgement Research supported by NIDCD grant 5R01DC6957