Grasping Variance in Word Norms: Individual Differences in Motor Imagery and Semantic Ratings

Word norming datasets have become an important resource for psycholinguistic research, and they are based on the underlying assumption that individual differences are inconsequential to the measurement of semantic dimensions. In this pre-registered study we tested this assumption by examining whether individual differences in motor imagery are related to variance in semantic ratings. We collected graspability ratings (i.e., how easily a word's referent can be grasped using one hand) for 350 words and also had each participant complete a series of motor imagery questionnaires. Using linear mixed effect models we tested whether measures of motor imagery ability (e.g., the Florida Praxis Imagery Questionnaire and the Test of Ability in Movement Imagery for Hands) and motor imagery vividness (e.g., the Vividness of Movement Imagery Questionnaire 2) could account for variance (raw and absolute difference scores) in graspability ratings. We observed a significant relationship between motor imagery vividness and absolute rating difference scores, wherein people with more vivid motor imagery provided ratings that were further from the mean word ratings. However there was no relationship between motor imagery and raw rating difference scores. The results suggest that there are measurable systematic differences in how participants make sensorimotor semantic ratings, which has implications for how sensorimotor semantic word norms are used for investigations of lexical semantic processing.