1. Individual differences in hemisphere asymmetry for nonword reading and their relationship to reading ability Suzanne E. Welcome 1, Christine Chiarello 1, Laura K. Halderman 1, Janelle Julagay 1, & Christiana Leonard 2 1 University of California, Riverside 2 University of Florida Individual differences in hemisphere asymmetry for nonword reading and their relationship to reading ability Suzanne E. Welcome 1, Christine Chiarello 1, Laura K. Halderman 1, Janelle Julagay 1, & Christiana Leonard 2 1 University of California, Riverside 2 University of Florida Participants 100 university students – 55 female, 45 male – 17% non-right handed – 18 to 34 years of age Demographic Measures Woodcock Reading Mastery Tests - Revised (Word Identification, Word Attack, and Passage Comprehension Subtests) Wechsler Abbreviated Scale of Intelligence Handedness Preference Questionnaire (Bryden, 1982) Annett Pegboard Task (Annett, 2002) Adult Reading History Questionnaire (Lefly & Pennington, 2000) Divided Visual Field (DVF) Tasks) Lexical Decision –Word/Nonword response made by key press Semantic Decision –Natural/Manmade response made by key press Masked Word Recognition –2-alternative forced choice of word immediately preceded and followed by mask (@/@/@) Word Naming (2 separate occasions) –Say presented word Nonword Naming –Say nonwords created by changing single letter of word Category Member Generation –Say an example of presented category (FRUIT – apple) Verb Generation –Say an action associated with presented noun (SCISSORS – cut) Methods Results Left Visual Field/Right Hemisphere Sole Predictor Variance Unique Variance (semi-partial r 2 ) Betat-value t-test sig of β Word Identification 0.05820.00000.0090.080NS Word Attack 0.06430.01750.1971.793NS Passage Comprehension 0.05990.0289-0.271-2.303 < 0.05 Verbal IQ 0.07860.00790.1401.204NS Performance IQ 0.00430.0043-0.088-0.887NS Lexical Decision LVF Acc 0.08070.00070.0310.348NS Word Naming LVF Acc 0.13870.0006-0.042-0.337NS Category Generation LVF Acc 0.38540.06410.3923.431 <.001 Masked Word Recognition LVF Acc 0.11280.00030.0230.246NS Verb Generation LVF Acc 0.41690.08860.4534.036 <.0001 Semantic Decision LVF Acc 0.13480.0013-0.054-0.484NS Right Visual Field/Left Hemisphere Sole Predictor Variance Unique Variance (semi-partial r 2 ) Betat-value t-test sig of β Word Identification 0.10490.0266 0.255 0.255 1.894 1.894NS Word Attack 0.08950.0183 0.210 0.210 1.573 1.573NS Passage Comprehension 0.05990.0270-0.289-1.911NS Verbal IQ 0.08240.0016 0.065 0.065 0.465 0.465NS Performance IQ 0.00080.0472-0.282-2.526 < 0.05 Lexical Decision RVF Acc 0.21760.0559 0.378 0.378 2.748 2.748 < 0.01 Word Naming RVF Acc 0.08140.0089-0.137-1.100NS Category Generation RVF Acc 0.08450.0066 0.102 0.102 0.946 0.946NS Masked Word Recognition RVF Acc 0.15980.0017 0.058 0.058 0.477 0.477NS Verb Generation RVF Acc 0.08160.0113 0.150 0.150 1.237 1.237NS Semantic Decision RVF Acc.13890.0200 0.203 0.203 1.645 1.645NS The experimental tasks that are most predictive of nonword naming performance differ between the left and right hemispheres. LVF/RH nonword naming performance is most strongly predicted by performance on semantic generation tasks (category member generation and verb generation) – For the LVF/RH, performance on semantic generation tasks alone is able to account for 47.9 percent of the variance in nonword naming accuracy. – For the RVF/LH, performance on the same tasks accounts for only 12.1 percent of the variance in nonword naming accuracy. RVF/LH nonword naming performance is most strongly predicted by performance on the lexical decision task – For the RVF/LH, performance on the lexical task alone is able to account for 21.8 percent of the variance in nonword naming accuracy – For the LVF/RH, performance on the same task accounts for only 8.1 percent of the variance in nonword naming accuracy. Nonword reading may be accomplished by somewhat different processes in the right and left hemispheres. In the right hemisphere, similar processes may be recruited by nonword naming and semantic generation tasks. –The presentation of a nonword to the right hemisphere may lead to the activation of multiple words that share orthography with the nonword. – Similarly, the semantic generation tasks involve the activation of multiple words. – It is possible that the right hemisphere’s role in nonword naming and in semantic generation tasks involves maintaining a range of possible responses. In the left hemisphere, similar processes may be recruited by nonword naming and lexical recognition processes. Conclusions More than one process may contribute to nonword reading. – Nonwords can be phonologically decoded. – The pronunciation of a nonword word can be inferred from the pronunciations of words with similar orthography (Goswami, 1986). Relationships between lateralized nonword naming performance and performance on other experimental tasks may yield insight into the nonword reading process used by each hemisphere. Multiple regression was performed in order to determine which experimental tasks were most predictive of nonword naming performance in each hemisphere. Introduction Annett M. (2002) Handedness and brain asymmetry: The right shift theory. New York: Taylor & Francis. Bryden, M. P. (1982) Laterality: Functional asymmetry in the normal brain. New York: Academic Press. Goswami U. (1986) Children's use of analogy in learning to read: A developmental study. Journal of Experimental Child Psychology, 42(1), 73-83. Lefly D.L, Pennington B.F. (2000) Reliability and validity of the adult reading history questionnaire. Journal of Learning Disabilities, 33(3), 286-296 Martino N.L., Hoffman, P.R. (2002) An investigation of reading and language abilities of college freshmen. Journal of Research in Reading, 25(3), 310-318 Patterson, K.E., Morton, J.C. (1985) From orthography to phonology: an attempt at an old interpretation. In K.E. Patterson, J.C. Marshall, & M.Coltheart (Eds.) Surface dyslexia: neuropsychological and cognitive studies of phonological reading (335-359). Hillsdale, NJ: Erlbaum Wechsler, D. (1999) Wechsler abbreviated scale of intelligence. San Antonio: Psychological Corporation. Woodcock, R. W. (1987) Woodcock Reading Mastery Tests, Revised. Circle Pines, MI: American Guidance Service. References This research was supported by NIH grant DC006957 awarded to the second and fourth authors. LVF/RH Nonword Naming Accuracy RVF/LH Nonword Naming Accuracy