Visual attention for linguistic and non-linguistic body actions in non-signing and native signing children.

Evidence from adult studies of deaf signers supports the dissociation between neural systems involved in processing visual linguistic and non-linguistic body actions. The question of how and when this specialization arises is poorly understood. Visual attention to these forms is likely to change with age and be affected by prior language experience. The present study used eye-tracking methodology with infants and children as they freely viewed alternating video sequences of lexical American sign language (ASL) signs and non-linguistic body actions (self-directed grooming action and object-directed pantomime). In Experiment 1, we quantified fixation patterns using an area of interest (AOI) approach and calculated face preference index (FPI) values to assess the developmental differences between 6 and 11-month-old hearing infants. Both groups were from monolingual English-speaking homes with no prior exposure to sign language. Six-month-olds attended the signer's face for grooming; but for mimes and signs, they were drawn to attend to the "articulatory space" where the hands and arms primarily fall. Eleven-month-olds, on the other hand, showed a similar attention to the face for all body action types. We interpret this to reflect an early visual language sensitivity that diminishes with age, just before the child's first birthday. In Experiment 2, we contrasted 18 hearing monolingual English-speaking children (mean age of 4.8 years) vs. 13 hearing children of deaf adults (CODAs; mean age of 5.7 years) whose primary language at home was ASL. Native signing children had a significantly greater face attentional bias than non-signing children for ASL signs, but not for grooming and mimes. The differences in the visual attention patterns that are contingent on age (in infants) and language experience (in children) may be related to both linguistic specialization over time and the emerging awareness of communicative gestural acts.

Effects of Video Reversal on Gaze Patterns during Signed Narrative Comprehension.

Language knowledge, age of acquisition (AoA), and stimulus intelligibility all affect gaze behavior for reading print, but it is unknown how these factors affect "sign-watching" among signers. This study investigated how these factors affect gaze behavior during sign language comprehension in 52 adult signers who acquired American Sign Language (ASL) at different ages. We examined gaze patterns and story comprehension in four subject groups who differ in hearing status and when they learned ASL (i.e. Deaf Early, Deaf Late, Hearing Late, and Hearing Novice). Participants watched signed stories in normal (high intelligibility) and video-reversed (low intelligibility) conditions. This video manipulation was used because it distorts word order and thus disrupts the syntax and semantic content of narratives, while preserving most surface phonological features of individual signs. Video reversal decreased story comprehension accuracy, and this effect was greater for those who learned ASL later in life. Reversal also was associated with more dispersed gaze behavior. Although each subject group had unique gaze patterns, the effect of video reversal on gaze measures was similar across all groups. Among fluent signers, gaze behavior was not correlated with AoA, suggesting that "efficient" sign watching can be quickly learnt even among signers exposed to signed language later in life.

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.

Tools for language: patterned iconicity in sign language nouns and verbs.

When naming certain hand-held, man-made tools, American Sign Language (ASL) signers exhibit either of two iconic strategies: a handling strategy, where the hands show holding or grasping an imagined object in action, or an instrument strategy, where the hands represent the shape or a dimension of the object in a typical action. The same strategies are also observed in the gestures of hearing nonsigners identifying pictures of the same set of tools. In this paper, we compare spontaneously created gestures from hearing nonsigning participants to commonly used lexical signs in ASL. Signers and gesturers were asked to respond to pictures of tools and to video vignettes of actions involving the same tools. Nonsigning gesturers overwhelmingly prefer the handling strategy for both the Picture and Video conditions. Nevertheless, they use more instrument forms when identifying tools in pictures, and more handling forms when identifying actions with tools. We found that ASL signers generally favor the instrument strategy when naming tools, but when describing tools being used by an actor, they are significantly more likely to use more handling forms. The finding that both gesturers and signers are more likely to alternate strategies when the stimuli are pictures or video suggests a common cognitive basis for differentiating objects from actions. Furthermore, the presence of a systematic handling/instrument iconic pattern in a sign language demonstrates that a conventionalized sign language exploits the distinction for grammatical purpose, to distinguish nouns and verbs related to tool use.