However, although there is evidence of the use of VE to induce emotions, and of the relationship between emotions and sense of presence, all of these studies used only sight and hearing stimuli. In fact, as mentioned above, research in VR using other senses such as touch or smell is very limited, even though some studies have emphasized the importance of improving VR experiences and suggested that including other stimuli (e.g. olfactory) could produce more immersive experiences, as long as the stimuli are consistent with the VE (Tortell et al., 2007). Other studies have proposed that using olfactory stimuli in VE could evoke certain emotions, which would have a direct impact on behavior (Baus & Bouchard, 2010). Along these lines, a recent review (Aiken & Berry, 2015) highlights the potential role of olfactory stimuli for improving VR exposure therapy, especially in the treatment of posttraumatic stress disorder, as smell can influence emotion and affective response, facilitate recall, or increase sense of presence.