Does perceived steepness deter stair climbing when an alternative is available?

Frank F. Eves Susannah K. S. Thorpe Amanda Lewis Guy A. H. Taylor-Covill Perception of hill slant is exaggerated in explicit awareness. Proffitt (Perspectives on Psychological Science 1 :110-122, 2006) argued that explicit perception of the slant of a climb allows individuals to plan locomotion in keeping with their available locomotor resources, yet no behavioral evidence supports this contention. Pedestrians in a built environment can often avoid climbing stairs, the man-made equivalent of steep hills, by choosing an adjacent escalator. Stair climbing is avoided more by women, the old, and the overweight than by their comparators. Two studies tested perceived steepness of the stairs as a cue that promotes this avoidance. In the first study, participants estimated the steepness of a staircase in a train station (n = 269). Sex, age, height, and weight were recorded. Women, older individuals, and those who were heavier and shorter reported the staircase as steeper than did their comparison groups. In a follow-up study in a shopping mall, pedestrians were recruited from those who chose the stairs and those who avoided them, with the samples stratified for sex, age, and weight status. Participants (n = 229) estimated the steepness of a life-sized image of the stairs they had just encountered, presented on the wall of a vacant shop in the mall. Pedestrians who avoided stair climbing by choosing the escalator reported the stairs as steeper even when demographic differences were controlled. Perceived steepness may to be a contextual cue that pedestrians use to avoid stair climbing when an alternative is available. - This article deals with the choices pedestrians make while navigating the environment. Perception of hills is exaggerated in explicit awareness; for example, a 5 hill is reported to be 20 (Bhalla & Proffitt, 1999; Proffitt, Bhalla, Gossweiler, & Midgett, 1995). Fatigue and added weight in a backpack increase these exaggerations. To climb hills, individuals require strength in their legs to raise their weight against gravity. Being tired or carrying a large bag would require a greater proportion of available strength to climb a hill than when unaffected by these factors, and individuals may adopt a slower speed of ascent to reflect any resource depletion (Proffitt, 2006). Importantly, exaggeration of hill slant is stratified by demographic grouping. With increasing age, leg strength declines (McCardle, Katch, & Katch, 2007), and older participants report steep hillsfor example, 25as steeper than do younger participants (Bhalla & Proffitt, 1999). Additionally, women report hills as steeper than do men (Proffitt et al., 1995). On average, women have lower leg strength than do men, coupled with a greater proportion of their body weight as fat (McCardle et al., 2007). Thus, an average woman has a lower strength-to-weight ratio than does an average manthat is, reduced resources for climbing. Although Proffitt has argued that effects of resource availability on explicit awareness of hill slant influence choicefor example, walking speedno behavioral evidence supports this contention. Parallel research in public health reveals that the effects of demographic grouping on hill perception are echoed by differences in pedestrian behavior at stairs. In many public access settings, such as train stations, pedestrians can avoid using resources to climb stairs by choosing an adjacent escalator. Pedestrians who carry large bags, are older, and are female avoid stairs more than do their comparison groups (Eves, 2013); naturally occurring pedestrian behavior mirrors the effects of demographic grouping on perceptual measures. In this behavioral evidence, however, groups with reduced resources for climbing are more likely to avoid further depletion. Thus, perceived slant may function as a cue that deters use of resources when an alternative is available. Demographic differences in perception of stair slant, a necessary precondition for this proposal, are tested in the first study. To date, no studies have reported the effects of body weight on slant perception, despite obvious parallels with the addition of weight in a backpack. Body mass index, the standardized measure of weight status, is calculated from weight in kilograms divided by height squared in meters. Inclusion of height in the index aims for a measure of weight status that standardizes the index across differences in overall size; for example, men are generally both taller and heavier than women. For perception of the environment, however, height is a variable of interest in its own right. Height of the eyes above the ground is related to the perception of the climbability of stairs (Mark, 1987; Mark & Vogele, 1987) and passability of apertures, such as doors (Warren & Whang, 1987; Wraga, 1999). Eye height can be used to scale the world into the intrinsic metrics of the perceiver. The first study tested height, as a proxy for eye height, and body weight as potential independent demographic associates of the perceptual variables. To measure perception of hill slant, termed geographical slant perception , Proffitt and co-workers obtained three different measures. Individuals report verbally the slope in degrees and perform a visual matching task to estimate the perceived angle of the slope in cross-section (Fig. 1). For the final measure, termed haptic , individuals adjust the slope of a palm-board with their hand until it is parallel with the hill facing them (see Fig. 2). Verbal and visual measures reveal exaggerated estimates of slope and are sensitive to differences in demographics, whereas the palm-board measure is both less prone to exaggeration and, generally, unaffected by demographic grouping (Bhalla & Proffitt, 1999; Proffitt et al., 1995),1 In a train station, verbal, visual, and palm-board measures of staircase slant were obtained at the foot of the stairs and at a distance of 15 m. We reasoned that if perceived slant were to influence behavioral choice, effects should be present before reaching the slope of the stair/escalator complex. In a major departure from previous studies of slant perception, the 1 Although Durgin, Hajnal, Li, Tonge, and Stigliani (2011) have argued that the relatively greater accuracy of palm-boards is an artifact of wrist motion and perception, a newly developed haptic measure that avoids reliance on the wrist joint revealed that this relative accuracy remained, particularly for the steeper slopes characteristic of staircases (TaylorCovill & Eves, 2013a). primary analyses used multiple regressions to test for simultaneous, independent influences of demographic variables. Since males are generally taller and heavier than women, the body size components of weight and height were mean centred for each sex to avoid confounding the effects of size with participants sex. Participants waiting for their train in a U.K. station with a 39step staircase (height = 6.45 m; overall angle, i (...truncated)