According to current models of spoken word recognition listeners understand speech as it unfolds over time. Eye tracking provides a non-invasive, on-line method to monitor attention, providing insight into the processing of spoken language. In the current project a spoken lexical processing assessment (LPA) confirmed current theories of spoken word recognition and investigated relationships between speed of lexical processing and intelligence, language skills and autism related traits. Participants were thirty-five young adult university students and thirty-five children between the ages of 7 years and 11 years 11 months. Lexical processing was assessed through the LPA, which measures the latency of eye fixation to images representing target nouns and was implemented on a Tobii T60 Eye Tracker. In addition, adults were administered the Wechsler Abbreviated Scale of Intelligence (WASI), the WMI index taken from the Wechsler Adult Intelligence Scale (WAIS-IV), and selected subtests from the Comprehensive Assessment of Spoken Language (CASL). Child participants were administered the Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV), and selected CASL subtests. Adult guardians of child participants completed the Social Responsiveness Scale (SRS) as it related to the participant. It was hypothesized that since auditory input is a primary mechanism by which children encounter language and are exposed to information during development, efficiency of lexical processing may act as a gatekeeper to the development of these skills. Results from the Lexical Processing assessment are consistent with predictions based on the cohort model of speech perception. Relationships between lexical processing speed, working memory, intelligence and linguistic skills were not evident in young adults. However in children, who are actively developing cognitive skills, we see clear relationships between speed of lexical processing and working memory, linguistic skills including vocabulary knowledge, syntax, and non-literal language comprehension, and traits related to the autism phenotype. The results of the current project indicate promise for the use of the lexical processing assessment not only in continued processing speed and autism-related research, but also point to potential utility in terms of early identification of children at risk for difficulty with language acquisition and deficits in social interaction. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]