Behavioral and neural correlates of deep and surface anaphora

Anaphora in language is defined as an expression that refers to another expression. Hankamer & Sag 1976 and Sag & Hankamer 1984 proposed that anaphors can be divided into deep anaphors, which are resolved using a non-linguistic discourse-level interpretation of the antecedent, and surface anaphors, which are resolved by accessing their antecedents at a linguistic level which is highly determined by surface syntactic structure. Previous behavioral studies of the differences between deep and surface anaphors have conflicting and inconsistent results. Additionally, no neuroimaging studies have previously been conducted on deep and surface anaphors or on verb-phrase anaphora in general. Using two sets of materials which differed in whether they used a surface or a deep anaphor, the behavioral and neural responses as a function of anaphor type were determined. One set of materials was used to examine the effect of placing an intervening sentence between the antecedent and anaphor (distance materials), and one set was used to examine the effect of shifted word order (particle shift materials), both of which were expected to affect surface anaphors more than deep anaphors. Behavioral responses were measured using naturalness ratings and self-paced reading times, and neural responses were measured using blood-oxygenlevel dependent (BOLD) signal differences obtained with functional magnetic resonance imaging (fMRI). Increasing the distance between the antecedent and anaphor affected surface anaphors more than deep anaphors in naturalness ratings, question response times, and BOLD signal, while altering word order had similar or insignificant effects on surface and deep anaphors. These results are consistent with Sag and Hankamer's idea that surface and deep anaphora are distinct categories that are processed differently, but are not consistent with the exact level of access of surface anaphora proposed by Sag and Hankamer. Instead, the results suggest that surface anaphors are more dependent on syntactic information that decays over distance than deep anaphors, but do not differ from deep anaphors in terms of accessing exact surface word order information. Thesis Supervisor: David Caplan Title: Professor of Neurology, Harvard Medical School Acknowledgements First, I would like to thank my advisor, David Caplan, for his guidance, support, and vast knowledge. I would also like to thank my thesis committee chair, Ted Gibson, for his help in setting up the initial experiments and his support along the way, and my third committee member, Frank Guenther, for his assistance and advice. I would also like to thank Satrajit Ghosh and Tom Zeffiro for their help with fMRI analysis techniques, Larry White for his assistance with setting up and running fMRI protocols, Rebecca Hufford for teaching me how to run MRI experiments, Jenna Calvino for assisting me with all the fMRI data collection, and Will Evans for helping with behavioral studies at BU. I am also grateful to my HST and SHBT professors for sharing their incredible wealth of information and inspiration. I would also like to thank Susan Voss, my undergraduate advisor, for inspiring me to pursue scientific research and for introducing me to the SHBT program. Special thanks goes to my SHBT classmates Miriam Makhlouf, Adam Furman, and Michael Slama who were always able to provide support, commiseration, and an excuse to go to Ma Soba for lunch. I would also like to thank my labmates Rebecca Hufford, Ricky Sachdeva, Joshua Levy, Jason MacMore, and Laura Horton for providing a supportive, intellectually exciting, and fun lab environment to work in over the past few years. Finally I would like to thank my family my mom, Sara, my dad, Sid, and my sister, Maya, who always believed in me, and my fiance, Jeff, for his encouragement, support, and superhuman patience.