Rapid Automatized Naming As a Marker of Genetic Liability to Autism: An Eye Tracking Study

Background: Rapid Automatized Naming (RAN) is a complex skill that indirectly measures the automaticity of cognitive and linguistic processes, associated with left hemispheric language and right cerebellar regions (Norton and Wolf, 2012). Evidence suggests that RAN is affected in autism spectrum disorder (ASD) and in the broad autism phenotype (BAP) among first-degree relatives (Losh et al., 2010; Hogan-Brown et al., 2014). Smaller eye voice span (EVS) (i.e., less lead in eye movement compared to speech) is associated with less fluent and automatized language processing in individuals with ASD and their siblings (Hogan-Brown, 2014). This study extends upon these findings by further examining eye movement during RAN in parents with and without the BAP, in addition to high functioning individuals with ASD. Comprehensive analyses of eye movements (e.g., EVS, saccades) in parents and individuals with ASD can provide fruitful clues into the automaticity and executive efforts exhibited during RAN and their genetic liability to ASD. 

Objectives: To use eye tracking to examine underlying mechanistic processes of RAN abilities in individuals with ASD and their parents, and explore correlations with conceptually related clinical-behavioral phenotypes.

Methods: Fifty-five individuals with ASD, 43 controls, 136 parents of individuals with ASD, and 57 control parents completed RAN on an eye tracker. The RAN task involved quickly naming arrays of stimuli (letters, colors, numbers, objects). Naming time and errors were measured. Eye-tracking analyses included three indices of automaticity and efficiency: 1) EVS; 2) average saccades per vocalization; and 3) perseverative saccades, the number of repeated saccades made at the target or a previously-visited target during a vocalization. The BAP was measured in parents using the Modified Personality Assessment (Tyrer, 1988).

Results: Results indicate slower naming time and more errors in individuals with ASD and their parents (ps <.05), with differences in parents restricted to the less highly automated color and object trials. Eye movement analyses show smaller EVS in individuals with ASD (p <.01) and similar trends in their parents. Individuals with ASD and their parents made more perseverative saccades (ps <.05) than controls. Eye movement differences were evident specifically in the BAP(+) group, and predicted narrative ability in parents. In ASD, errors were associated with restricted and repetitive behaviors (RRBs) and errors and saccadic patterns were associated with poorer pragmatic language and narrative abilities (ps <.05).

Conclusions: Differences in RAN performance and associated eye movements indicate reduced automaticity in ASD and the BAP. This illustrates the reliance on greater attentional and executive resources during language processing among these groups. Further, associations between RAN time, errors, and perseverative saccades were associated with rigid personality traits in parents and restricted and repetitive behaviors in their children, highlighting perseverative tendencies commonly implicated in ASD (Hill 2004). Together, results suggest that reduced automaticity is associated with downstream cognitive indices of executive flexibility and language, emphasizing automaticity as a critical precursor to complex language skills and a potential indicator of genetic liability to ASD.