The Cortical Organization of Syntactic Processing Is Supramodal: Evidence from American Sign Language.

Areas within the left-lateralized neural network for language have been found to be sensitive to syntactic complexity in spoken and written language. Previous research has revealed that these areas are active for sign language as well, but whether these areas are specifically responsive to syntactic complexity in sign language independent of lexical processing has yet to be found. To investigate the question, we used fMRI to neuroimage deaf native signers' comprehension of 180 sign strings in American Sign Language (ASL) with a picture-probe recognition task. The ASL strings were all six signs in length but varied at three levels of syntactic complexity: sign lists, two-word sentences, and complex sentences. Syntactic complexity significantly affected comprehension and memory, both behaviorally and neurally, by facilitating accuracy and response time on the picture-probe recognition task and eliciting a left lateralized activation response pattern in anterior and posterior superior temporal sulcus (aSTS and pSTS). Minimal or absent syntactic structure reduced picture-probe recognition and elicited activation in bilateral pSTS and occipital-temporal cortex. These results provide evidence from a sign language, ASL, that the combinatorial processing of anterior STS and pSTS is supramodal in nature. The results further suggest that the neurolinguistic processing of ASL is characterized by overlapping and separable neural systems for syntactic and lexical processing.

The effect of being human and the basis of grammatical word order: Insights from novel communication systems and young sign languages.

This study identifies a central factor that gives rise to the different word orders found in the world's languages. In the last decade, a new window on this long-standing question has been provided by data from young sign languages and invented gesture systems. Previous work has assumed that word order in both invented gesture systems and young sign languages is driven by the need to encode the semantic/syntactic roles of the verb's arguments. Based on the responses of six groups of participants, three groups of hearing participants who invented a gestural system on the spot, and three groups of signers of relatively young sign languages, we identify a major factor in determining word order in the production of utterances in novel and young communication systems, not suggested by previous accounts, namely the salience of the arguments in terms of their human/animacy properties: human arguments are introduced before inanimate arguments ('human first'). This conclusion is based on the difference in word order patterns found between responses to depicted simple events that vary as to whether both subject and object are human or whether the subject is human and the object inanimate. We argue that these differential patterns can be accounted for uniformly by the 'human first' principle. Our analysis accounts for the prevalence of SOV order in clauses with an inanimate object in all groups (replicating results of previous separate studies of deaf signers and hearing gesturers) and the prevalence of both SOV and OSV in clauses with a human object elicited from the three groups of participants who have the least interference from another linguistic system (nonliterate deaf signers who have had little or no exposure to another language). It also provides an explanation for the basic status of SOV order suggested by other studies, as well as the scarcity of the OSV order in languages of the world, despite its appearance in novel communication systems. The broadest implication of this study is that the basic cognitive distinction between humans and inanimate entities is a crucial factor in setting the wheels of word ordering in motion.