http://www.psychol.cam.ac.uk/cece/research#section-1
"ecological approaches suggest that perception may depend on contextual factors not previously considered. For example, research shows that hills seem steeper to a person wearing a heavy backpack. Contextual factors influence perception because they are relevant to actions: A hill is harder to climb for an encumbered person, and thus, appears as steeper. We showed that a psychosocial resource, social support, can also affect the visual perception of slants (Schnall, Harber, Stefanucci & Proffitt, 2008). Further, after having consumed glucose people find a hill less steep than after having consumed noncaloric sweetener, presumably because glucose provides energy (Schnall, Zadra & Proffitt, 2010). Thus, whether or not one has resources available changes how one sees the physical world."
