The new Mobile Universal Lexicon Evaluation System (MULES): A test of rapid picture naming for concussion sized for the sidelines

Abstract

Objective: Measures of rapid automatized naming (RAN) have been used for over 50 years to capture vision-based aspects of cognition. The Mobile Universal Lexicon Evaluation System (MULES) is a test of rapid picture naming under investigation for detection of concussion and other neurological disorders. MULES was designed as a series of 54 grouped color photographs (fruits, random objects, animals) that integrates saccades, color perception and contextual object identification. Recent changes to the MULES test have been made to improve ease of use on the athletic sidelines. Originally an 11 × 17-inch single-sided paper, the test has been reduced to a laminated 8.5 × 11-inch double-sided version. We identified performance changes associated with transition to the new, MULES, now sized for the sidelines, and examined MULES on the sideline for sports-related concussion.

Methods: We administered the new laminated MULES to a group of adult office volunteers as well as youth and collegiate athletes during pre-season baseline testing. Athletes with concussion underwent sideline testing after injury. Time scores for the new laminated MULES were compared to those for the larger version (big MULES).

Results: Among 501 athletes and office volunteers (age 16 ± 7 years, range 6-59, 29% female), average test times at baseline were 44.4 ± 14.4 s for the new laminated MULES (n = 196) and 46.5 ± 16.3 s for big MULES (n = 248). Both versions were completed by 57 participants, with excellent agreement (p < 0.001, linear regression, accounting for age). Age was a predictor of test times for both MULES versions, with longer times noted for younger participants (p < 0.001). Among 6 athletes with concussion thus far during the fall sports season (median age 15 years, range 11-21) all showed worsening of MULES scores from pre-season baseline (median 4.0 s, range 2.1-16.4).

Conclusion: The MULES test has been converted to an 11 × 8.5-inch laminated version, with excellent agreement between versions across age groups. Feasibly administered at pre-season and in an office setting, the MULES test shows preliminary evidence of capacity to identify athletes with sports-related concussion.

Keywords: Concussion; Mobile Universal Lexicon Evaluation System (MULES); Picture naming; Saccades; Sports; Vision.

Fig. 1

The Mobile Universal Lexicon Evaluation System (MULES) test of rapid picture naming, as examined in the present manuscript (MULES Test © New York University, text and photographs, registration number TXu002026665, all rights reserved). The laminated MULES is printed two-sided on an 8.5 × 11-inch sheet of paper and includes 54 original photographs of fruits, objects and animals. The participant names the pictures orally from left to right as rapidly as possible. The score is the time in seconds required to name all pictures (participant flips the laminated sheet of paper during test timing).

Fig. 2

Box plots demonstrating average baseline scores in seconds for each MULES version (big vs. laminated). The average big MULES baseline score (n = 248) was 46.5 ± 16.3 s and the average baseline score for the laminated MULES was (n = 196) 44.4 ± 14.4 s. Accounting for participant age, MULES version (big vs. laminated) was not a significant predictor of baseline score (p = 0.52, logistic regression).

Fig. 3

Box plots demonstrating average scores for trials 1 and 2 for each MULES version (big vs. laminated). Median inter-trial difference for the big MULES (n = 248) was 6.6 s, while the median inter-trial difference for laminated MULES (n = 196) was 6.1 s. Accounting for participant age, MULES version (big vs. laminated) was not a significant predictor of inter-trial difference, or degree of learning effect between the two trials (p = 0.31, logistic regression).

Fig. 4

Scatter plot of big vs. laminated MULES baseline scores for participants who completed both test versions (n = 57). Linear correlation demonstrates strong agreement between baseline scores of each version (r = 0.89, p < 0.0001). Accounting for participant age, big MULES scores were significant predictors of time scores for the new laminated version (p < 0.001, linear regression).