Vestibular loss can co-occur with hearing loss causing dual sensory deficits. Unfortunately, children with hearing loss are rarely assessed for vestibular loss. As a result, the impact of co-morbid vestibular loss in children with hearing loss is unknown, particularly on academic and cognitive outcomes. While vestibular loss has been speculated to affect reading outcomes in children (Braswell 2006a; Snashall 1983; Tomaz 2014), the extent to which vestibular loss affects reading outcomes and the association between vestibular loss and reading is not understood. Therefore, the purpose of this proposal is to investigate the relationship between reading outcomes and vestibular loss in children with hearing loss. The vestibular system is responsible for decoding head movement and eliciting eye movements in an equal and opposite direction to maintain steady vision. It is not surprising therefore that vestibular loss results in reduced dynamic visual acuity - the ability to see clearly during head movement - (Rine 2003; Janky 2015); however, children with vestibular loss and reduced dynamic visual acuity also have reduced reading acuity - the smallest print size that can be read - and require larger print size for reading compared to peers with normal hearing (Braswell 2006a). Thus, Aim 1 will test the hypothesis that vestibular loss results in visual acuity deficits due to vestibulo-ocular reflex and cognitive deficits, which could impact reading. Theoretically, the Simple View of Reading (Gough 1986) suggests that reading comprehension can be explained by decoding and language comprehension abilities; however, these two factors do not account for all the variance in reading comprehension (Aaron 1999). In children with hearing loss, reading is affected by language, phonological processing, and auditory access; however, these factors alone do not fully explain the variance. Aim 2 will test the hypothesis that after controlling for variables known to contribute to reading performance (i.e., language, phonological processing, auditory access, etc.), vestibular loss will account for a significant amount of the variance in reading outcomes. The long-term goals of this research program are to define the developmental and academic impact of comorbid vestibular loss and then develop rehabilitative strategies that mitigate negative outcomes. The proposed work will provide a better understanding of vestibular loss as a contributing factor to reading difficulties for children with hearing loss, where previously only the effects of hearing loss have been considered. The proposed work will improve the scientific understanding of reading deficits in children with hearing loss and could lead to new rehabilitative interventions for reading in children with hearing loss by considering vestibular loss, a factor that has until now been ignored. A scaffolded training plan has been devised to enhance the investigator's understanding of literacy outcomes in children with hearing loss, cognition, neuroanatomy, development, and the ability to incorporate eye tracking to address the hypotheses.
