The purpose of this study was to compare the first-time neurocognitive concussion baseline outcomes, using the Cognigram assessment software, between American and Brazilian professional bull riders. The analysis was performed using the database provided by the Professional Bull Riding Association Sports Medicine staff. The Cognigram assessment measures and analyses four outcomes: Psychomotor Function, Attention, Learning, and Working Memory Speed. The study examined the test outcomes of 210 professional bull riders (150 American, 60 Brazilian). A one-way multivariate analysis of covariance (MANCOVA) was used to determine if there a significant difference in the four assessment outcomes when comparing the country of origin subject groups. The results of the analysis reported country of origin has a significant effect on the assessment outcomes, F(8, 406) = 6.407, p < 0.001, Wilks' [lambda] = 0.788, partial [eta][superscript 2] = 0.112. Post hoc analysis reported significant differences in three outcomes (Bonferroni correction, [alpha] = 0.012): Psychomotor Function, F(2, 206) = 21.25, p < 0.001, partial [eta][superscript 2] = 0.17, Attention, F(2, 206) = 18.90, p < 0.001, partial [eta][superscript 2] = 0.16, and Working Memory Speed, F(2, 206) = 7.70, p < 0.001, partial [eta][superscript 2] = 0.07. Country of Origin did not have a significant effect on Learning, F(2, 206) = 1.14, p = 0.321, partial [eta][superscript 2] = 0.01. Extrinsic factors (Testing environment and format and familiarity of testing content) and intrinsic factors (time orientation and physical and mental status at the time of testing) could have significant effects on the disparity between the two groups, affecting assessment outcomes. If cultural bias has a significant effect on Cognigram assessment outcomes, this poses a threat to the validity of the assessment toll; and this may contribute to an increase in the probability of under diagnosis of sport related concussions for Brazilian bull riders. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]