In detecting deception, the Cognitive Load hypothesis states that lying requires more cognitive resources compared to truth telling. Further, increases in cognitive load are predicted to decrease respiratory sinus arrhythmia (RSA). We evaluated the impact of cognitive tasks and the intent to deceive on RSA in 40 male, native Arabic-speaking participants quasi-randomized into truthful (n=14) or deceptive (n=26) groups. Participants donned an ambulatory physiologic recording device and completed cognitive testing after receiving translated instructions about their role in an impending mock crime. The results show that a decrease in RSA recorded during the cognitive testing was greater in individuals who were about to commit a deceptive act.