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Poster D41, Friday, August 17, 4:45 – 6:30 pm, Room 2000AB

Visual stream semantic priming of reading aloud and lexical decision

Josh Neudorf1, Chelsea Ekstrand2, Shaylyn Kress3, Alexandra Neufeldt4, Ron Borowsky5;1University of Saskatchewan, 2University of Saskatchewan, 3University of Saskatchewan, 4University of Saskatchewan, 5University of Saskatchewan

INTRODUCTION Converging evidence supports a distributed-plus-hub view of semantic processing, in which there are distributed modular semantic sub-systems for processing action, shape, and colour connected to an amodal semantic hub supporting integration of semantic representations (e.g., Patterson et al., 2007). Furthermore, object semantic processing of colour and shape, and lexical reading/decision, are processed mainly along the ventral stream, while action semantic processing, and phonetic decoding, occur mainly along the dorsal stream (e.g., Goodale & Milner, 1992; Borowsky et al., 2007). Priming was used to examine the sharing of the action semantic sub-system with the dorsal-sublexical reading stream, and the visual semantic sub-system with the ventral-lexical reading stream. METHODS In four experiments, participants read prime words that required imagining either the object or action referent in order to semantically prime one of the visual processing streams. In Experiment 1, they then named a lexical word target or sublexical pseudohomophone (PH) target. In Experiment 2, targets were degraded by decreasing the contrast to examine processing at the encoding level (Neudorf et al., 2018 under review). Experiments 3 and 4 were lexical decision tasks (LDTs) using the same primes and target words with either legal nonword (NW; Experiment 3) or PH (Experiment 4) foils. RESULTS In a Linear Mixed Model analysis of reaction time, object priming consistently produced faster reaction times for word targets in reading aloud and the LDT than action priming, reflecting the degree of shared-stream processing between imagined object primes and word targets. The priming effects were similar in size within each type of target, reflecting the degree of amodal priming, with the exception of PH foil LDT (Experiment 4), where action priming was eliminated. In the presence of PH foils, the LDT priming effect size was attenuated relative to the NW foil condition, which was expected given that NW foils allow semantics and phonology to assist with the task, wheras the PH foil condition does not. Additionally, the size of priming was similar between intact and degraded stimulus quality conditions, thus ruling out encoding as a locus for effects. CONCLUSION The results are consistent with an account of shared-stream processing for word reading and object semantic priming. These findings also support the existence of an amodal semantic hub integrating information from semantic modalities. The prediction that priming would be attenuated with PH foil types compared to NW foil types in LDT was confirmed, supporting the idea that simple prime-target associations in orthography can not completely account for these effects. Priming of naming was not affected by stimulus quality, indicating that priming did not feed back to the level of encoding. This research extends the distributed-plus-hub model (Patterson et al., 2007) to include shared-stream processing advantages for the ventral visual stream, and provides a novel paradigm that we are exploring in functional Magnetic Resonance Imaging. ACKNOWLEDGMENTS/FUNDING SOURCES: NSERC USRA 2017 and NSERC CGSM 2017/2018 to JN, NSERC CGSD to CE, NSERC Discovery Grant to RB

Topic Area: Meaning: Lexical Semantics