Within tranquillity studies, much of the emphasis has been placed on understanding the role of vision in the perception of natural environments, which is probably not surprising, considering that upon first viewing a scene its configurational coherence can be established with incredible speed. Indeed, scene information can be captured in a single glance and the gist of a scene determined in as little as 100ms. The speed of processing of complex natural images was tested by Thorpe "et al." using colour photographs of a wide range of animals (mammals, birds, reptiles and fish), in their natural environments, mixed with distracters that included pictures of forests, mountains, lakes, buildings and fruit. During this experiment, subjects were shown an image for 20ms and asked to determine whether it contained an animal or not. The electrophysiological brain responses obtained in this study showed that a decision could be made within 150ms of the image being seen, indicating the speed at which cognitive visual processing occurs.