This study systematically investigated the interaction between low-level statistics in unmanipulated natural scenes and the processes that underlie perceptual decision-making (using the Drift Diffusion Model). Results indicate that scene complexity, as indexed by two parameters (spatial coherence and contrast energy), modulates perceptual decisions through the speed of information processing and evidence requirements. Experiment 2a/b refined these observations by showing how the isolated manipulation of SC alone results in weaker but comparable effects on decision-making, whereas the manipulation of only CE has no effect. Using natural stimuli has helped us to reveal a new pattern, with task performance being best on intermediate trials. Overall, these results show that very basic, task-irrelevant, properties of our natural environment influence perceptual-decision making.