The “New Look” in perception, a movement in the 1950s (Bruner, 1957), maintained that rather than being a passive registration of reality, perception reflected internal expectations and motivations as part of an adaptive process. That movement quickly ran its course without having much impact, but, today, research again suggests that perception of the physical world is influenced by emotion and other internal factors. For example, Proffitt and colleagues (e.g., Bhalla & Proffitt, 1999; Proffitt, Stefanucci, Banton & Epstein, 2003; Witt, Proffitt, & Epstein, 2004) have found that hills appear steeper and distances farther to people with reduced physical resources, either from wearing a heavy backpack, being physically tired, or being elderly. Recent research shows that emotion can have similar effects. In one study (Riener, Stefanucci, Proffitt, & Clore, 2003) participants listened to happy or sad music as they stood at the bottom of a hill. The results showed that sadness can make mountains out of molehills. Sad mood led to overestimation of the incline on verbal and visual measures, but not on a haptic measure. That is, the sad individuals were more likely to say that the hill was steeper compared to happy individuals, but both groups provided similar haptic responses.
Affective feelings thus appear to inform explicit, but not implicit measures of perception. That is, when asked to estimate the incline verbally in degrees (i.e., verbal measure) and when indicating the incline analogically with a sort of protractor (i.e., visual measure), individuals feeling sad estimated the hill to be significantly steeper than individuals who were feeling happy or who had not heard any music. Such perceptual measures are thought to reflect conscious visual perception that relies on processing in the ventral visual stream, or “what” system, concerned with visual identification (Milner & Goodale, 1995). A reasonable argument can be made for why this system might be sensitive to resources for coping with inclines and distances (Proffitt, 2006). The third, haptic measure involved tilting a palm board (without looking at it) to match the incline of the hill. This haptic measure of incline is generally found to be quite accurate and to be immune from the influence of resource depletion such as physical exhaustion. It was also unaffected by sad mood. The measure is thought to reflect unconscious visual perception and relies on processing in the dorsal visual stream, or “how” system, engaged in the visual control of motor behaviour. Whereas it might be adaptive for one’s perception of a hill to reflect one’s resources, as decisions on whether to take action or not might hinge on such information, but for regulation of one’s actual foot placement, such overestimations might be disastrous.