THE MEXICAN JOURNAL OF BEHAVIOR ANALYSIS (MJBA), (ISSN-0185-4534) is published twice a year (June and December) by the Mexican Society for Behavior Analysis. The MJBA publishes original basic or applied research reports relevant to the behavior of nonhuman animals and humans. Review, theoretical articles, technical notes, and brief research reports are also considered for publication. The MJBA is a bilingual journal, publishing papers in either Spanish or English. Abstracts in both languages are also included for each article.