Oculomotor chronometry of spoken word structure processing

Oculomotor inhibition (OMI) is the momentary inhibition of involuntary eye movements, such as saccades and blinks, following sensory stimulation. Higher-level cognitive processes, such as processing the structure of written words, have been shown to affect the duration and magnitude of the OMI. In this study we tested whether OMI measures are influenced by the processing of spoken word structures. Participants listened to Hebrew words and pseudowords presented auditorily while we recorded their microsaccades, eye blinks, and pupil dilation. Spoken pseudowords were divided into two groups based on their underlying linguistic structure, with one half containing real roots and the other half containing invented roots. Results show a greater OMI for Real-root pseudowords as compared to Invented-root pseudowords, replicating the morpheme interference effect found previously for written stimuli. OMI measures, including microsaccade and eye blink latencies, as well as pupil dilation peak latency, were consistently greater for real-root pseudowords compared to invented-root pseudowords. These findings demonstrate the sensitivity of OMI to the cognitive processing of spoken word structure, even in the absence of visual stimuli or visually directed task. The results highlight the potential role of oculomotor responses as a marker of higher-order linguistic processing.