Investigates potential alterations in decision making in presurgical mesiotemporal lobe epilepsy (TLE) patients. It is hypothesized that TLE patients exhibit disadvantageous decision making under implicit conditions which is mainly based on the processing of emotional feedback. Participants were 20 patients (14 females, 18-53 years old, mean age 33.7 years) diagnosed with intractable unilateral TLE and 20 healthy volunteers (14 females, mean age 33.6 years) making up the control group (CG). Measures included the Verbal Learning and Memory Test (VLMT), the Rey Auditory Verbal Learning Test (AVLT), and the Wechsler Memory Scale - Revised (WMS-R). Subjects took part in the computerized version of the Iowa Gambling Task (IGT) and the Game of Dice Task (GDT). Results demonstrated that in patients with TLE alterations in decision making, selectivity occur in ambiguous situations whilst decision making under risk conditions is normal. As hypothesized, patients selected disadvantageous alternatives on the IGT more frequently than CG subjects. It was also clearly demonstrated that disadvantageous decision making is not a consequence of epilepsy surgery. Additionally, not all patients exhibited disadvantageous decision making, with 9 choosing advantageous alternatives. Within the entire patient group, better executive subcomponents were related to advantageous IGT decision making. It is concluded that these results hint that, in addition to the amygdala, the hippocampus might be another mesiotemporal structure that is crucially involved in feedback driven decision making based on implicit probabilities. In conclusion, future study aims are discussed.