Mobile Universal Lexicon Evaluation System (MULES) test: A new measure of rapid picture naming for concussion

Objective This study introduces a rapid picture naming test, the Mobile Universal Lexicon Evaluation System (MULES), as a novel, vision-based performance measure for concussion screening. The MULES is a visual-verbal task that includes 54 original photographs of fruits, objects and animals. We piloted MULES in a cohort of volunteers to determine feasibility, ranges of picture naming responses, and the relation of MULES time scores to those of King-Devick (K-D), a rapid number naming test. Methods A convenience sample (n = 20, age 34 ± 10) underwent MULES and K-D (spiral bound, iPad versions). Administration order was randomized; MULES tests were audio-recorded to provide objective data on temporal variability and ranges of picture naming responses. Results Scores for the best of two trials for all tests were 40–50 s; average times required to name each MULES picture (0.72 ± 0.14 s) was greater than those needed for each K-D number ((spiral: 0.33 ± 0.05 s, iPad: 0.36 ± 0.06 s, 120 numbers), p < 0.0001, paired t-test). MULES scores showed the greatest degree of improvement between trials (9.4 ± 4.8 s, p < 0.0001 for trials 1 vs. 2), compared to K-D (spiral 1.5 ± 3.3 s, iPad 1.8 ± 3.4 s). Shorter MULES times demonstrated moderate and significant correlations with shorter iPad but not spiral K-D times (r = 0.49, p = 0.03). Conclusion The MULES test is a rapid picture naming task that may engage more extensive neural systems than more commonly used rapid number naming tasks. Rapid picture naming may require additional processing devoted to color perception, object identification, and categorization. Both tests rely on initiation and sequencing of saccadic eye movements.