The Symbol Digit Modalities Test (SDMT) is an information processing speed test. The aim of this study was to compare the SDMT across three samples: the USA, Mexico, and Argentina. The hypothesis is that performance will vary based on native language and cultural differences between these countries. The SDMT was administered to 129 healthy volunteers. Participants from the USA performed better than participants from Argentina and Mexico (p < .01), and no differences were observed between the latter groups (p = .15). Processing speed differs between the studied populations of Latin America and Anglo-America. Possible interpretations of this result are presented.