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

Interrupting Pedestrians in Indonesia; Effect of Climate on Perceived Steepness and Stair Climbing Behaviour

Increased activity during daily life is one public health initiative to reduce population inactivity. Increasing temperature and humidity influence walking for transport by reducing the blood supply available to exercising muscles. This study investigated effects of temperature and humidity on a perceptual cue, estimated stair slant, that can influence behaviour, and on subsequent speed of climbing. Participants (402 males, 423 females) estimated the slant of a 20.4° staircase at a university in Indonesia. Subsequently, the participants were timed covertly while climbing. As temperature and humidity increased, estimated stair slant became more exaggerated. Females estimated stair slant as steeper than males. For stair climbing, speed was reduced as temperature increased, and females climbed slower than males. Estimates of stair slant were not associated with speed of the subsequent climb. Climate influences estimates of stair slant that precede stair climbing and subsequent speed of the ascent. In this study, perception was unrelated to behaviour.

EXPRESS: "Run to the hills": Specific contributions of anticipated energy expenditure during active spatial learning

Grounded views of cognition consider that space perception is shaped by the body and its potential for action. These views are substantiated by observations such as the distance-on-hill effect, described as the overestimation of visually perceived uphill distances. An interpretation of this phenomenon is that slanted distances are overestimated because of the integration of energy expenditure cues. The visual perceptual processes involved are however usually tackled through explicit estimation tasks in passive situations. The goal of this study was to consider instead more ecological active spatial processing. Using immersive virtual reality and an omnidirectional treadmill, we investigated the effect of anticipated implicit physical locomotion cost by comparing spatial learning for uphill and downhill routes, while maintaining actual physical cost and walking speed constant. In the first experiment, participants learnt city layouts by exploring uphill or downhill routes. They were then tested using a landmark positioning task on a map. In the second experiment, the same protocol was used with participants who wore loaded ankle weights. Results from the first experiment showed that walking uphill routes led to a global underestimation of distances compared to downhill routes. This inverted distance-of-hill effect was not observed in the second experiment, where an additional effort was applied. These results suggest that the underestimation of distances observed in experiment one emerged from recalibration processes whose function was to solve the transgression of proprioceptive predictions linked with uphill energy expenditure. Results are discussed in relation to constructivist approaches on spatial representations and predictive coding theories.

Physical fatigue and its effect on road crossing decisions: an examination of the embodied perception perspective

Road crossing is an everyday task that requires integration of information (e.g., speed and distance of an oncoming vehicle) to effectively guide behaviour. The embodied perception perspective suggests that individuals' perception of environmental stimuli is influenced by their psychophysiological state. Upon this premise, the current study examined whether acute physical fatigue influences visual perception and associated decision-making in road crossing. Using a between-subject design, 54 participants (healthy adults, aged 18-35) were divided into a fatigue and no-fatigue group. To manipulate fatigue, participants completed a vigorous cycling protocol (fatigue group) or a light cycling protocol (no-fatigue group) prior to completing a video-based examination of road crossing decisions (cross vs. not cross; action-based) and verbal judgments of speed and distance of an oncoming vehicle. Measures of heart rate, self-perceived recovery, and preferred walking speed indicated that fatigue was successfully induced (all p's < 0.03). Participants effectively distinguished between different speeds (30-50-70 km/h; p < 0.001), and distances (10-100 m in 10 m increments; p < 0.001). Moreover, both vehicle speed and distance (p's < 0.001) significantly influenced road crossing decisions. However, no significant effects of fatigue were observed for visual perception or road crossing decisions (all p's > 0.26). This study demonstrated that individuals are sensitive to changes in vehicle speed and distance and respond to these changes in making road crossing decisions. In contrast to the embodied perception perspective, however, physical fatigue did not alter perceptual judgments of vehicle speed and distance nor did it influence road crossing decisions in a video-simulated road crossing environment.

Human and machine: Evaluating whether action automation influences visual perception

The action-specific account of perception suggests that our perceptual system is influenced by information about our ability to act in our environment and, thus, affects our perception. However, the specific information about action that is influential for perception is still largely unknown. For example, if a goal is achieved through automation rather than action, is perception influenced because the goal was achieved or is perception immune because the act was automated rather than performed by the observer? In four experiments, we examined whether automating a paddle to block a moving ball in a computer game similar to Pong affects perception of the ball's speed. Results indicate that the automation used here did not affect speed perception of the target. Whereas tools such as reach-extending sticks and various-sized paddles are both incorporated into one's body schema and also influence spatial perception, automation, our results imply that automation is not incorporated into one's body schema and does not affect spatial perception. The dissociation in how the mind treats tools versus automation could have several implications as automation becomes more prevalent in daily life.

When weight is an encumbrance; avoidance of stairs by different demographic groups

BACKGROUND

Locomotion is an energy costly behaviour, particularly when it entails raising weight against gravity. Minimization of locomotor costs appears a universal default. Avoidance of stair climbing helps humans minimise their energetic costs. In public access settings, demographic subgroups that raise more 'dead' weight than their comparison groups when climbing are more likely to avoid stairs by choosing the escalator. Individuals who minimise stair costs at work, however, can accumulate a deficit in energy expenditure in daily life with potential implications for weight gain. This paper tests the generality of avoidance of stairs in pedestrians encumbered by additional weight in three studies.

METHODS

Pedestrian choices for stairs or the alternative were audited by trained observers who coded weight status, presence of large bags and sex for each pedestrian. Sex-specific silhouettes for BMIs of 25 facilitated coding of weight status. Choices between stairs and a lift to ascend and descend were coded in seven buildings (n = 26,981) and at an outdoor city centre site with the same alternatives (n = 7,433). A further study audited choices to ascend when the alternative to stairs was a sloped ramp in two locations (n = 16,297). Analyses employed bootstrapped logistic regression (1000 samples).

RESULTS

At work and the city centre site, the overweight, those carrying a large bag and females avoided both stair climbing and descent more frequently than their comparison groups. The final study revealed greater avoidance of stairs in these demographic subgroups when the alternative means of ascent was a sloped ramp.

DISCUSSION

Minimization of the physiological costs of transport-related walking biases behaviour towards avoidance of stair usage when an alternative is available. Weight carried is an encumbrance that can deter stair usage during daily life. This minimization of physical activity costs runs counter to public health initiatives to increase activity to improve population health.

The uphill battle for action-specific perception

The action-specific account of perception states that a perceiver's ability to act influences the perception of the environment. For example, participants tend to perceive distances as farther when presented up hills than on the flat ground. This tendency is known as the distance-on-hill effect. However, there is debate as to whether these types of effects are truly perceptual. Critics of the action-specific account of perception claim that the effects could be due to participants guessing the hypothesis and trying to comply with the experimental demands. The present study aims to explore the distance-on-hill effect and determine whether it is truly perceptual or whether past results were due to response bias. Participants judged the relative distance to targets on a hill and the flat ground. We found the distance-on-hill effect in virtual reality using a visual matching task. The distance-on-hill effect persisted even when participants were given explicit feedback about their estimates. We also found that the effect went away, as predicted by a perceptual explanation, when participants had to match the distance between two cones that were both on hills. These results offer important steps toward the painstaking task of determining whether action's effect on perception is truly perceptual.

Perceptual Modification of the Built Environment to Influence Behavior Associated with Physical Activity: Quasi-Experimental Field Studies of a Stair Banister Illusion

BACKGROUND

Re-engineering the built environment to influence behaviors associated with physical activity potentially provides an opportunity to promote healthier lifestyles at a population level. Here we present evidence from two quasi-experimental field studies in which we tested a novel, yet deceptively simple, intervention designed to alter perception of, and walking behavior associated with, stairs in an urban area.

OBJECTIVES

Our objectives were to examine whether adjusting a stair banister has an influence on perceptions of stair steepness or on walking behavior when approaching the stairs.

METHODS

In study 1, we asked participants (n = 143) to visually estimate the steepness of a set of stairs viewed from the top, when the stair banister was adjusted so that it converged with or diverged from the stairs (± 1.91°) or remained neutral (± 0°). In study 2, the walking behavior of participants (n = 36) was filmed as they approached the stairs to descend, unaware of whether the banister converged, diverged, or was neutral.

RESULTS

In study 1, participants estimated the stairs to be steeper if the banister diverged from, rather than converged with, the stairs. The effect was greater when participants were unaware of the adjustment. In study 2, walking speed was significantly slower when the banister diverged from, rather than converged with, the stairs.

CONCLUSIONS

These findings encourage us to speculate about the potential to economically re-engineer features of the built environment to provide opportunities for action (affordances) that invite physical activity behavior or even promote safer navigation of the environment.

Social and Contextual Constraints on Embodied Perception

A number of papers have challenged research on physiological and psychological influences on perception by claiming to show that such findings can be explained by nonperceptual factors such as demand characteristics. Relatedly, calls for separating perception from judgment have been issued. However, such efforts fail to consider key processes known to shape judgment processes: people's inability to report accurately on their judgments, conversational dynamics of experimental research contexts, and misattribution and discounting processes. Indeed, the fact that initially observed effects of embodied influences disappear is predicted by an extensive amount of literature on judgments studied within social psychology. Thus, findings from such studies suggest that the initially presumed underlying processes are at work-namely, functional considerations that are informative in the context of preparing the body for action. In this article, I provide suggestions on how to conduct research on perception within the social constraints of experimental contexts.

Bioenergetic costs and state influence distance perception

Bioenergetic resources and states have been found to influence visual perception, with greater expected energy expenditure being associated with perceptions of greater distances and steeper slopes. Here we tested whether resting metabolic rate (RMR), which can serve as a proxy for the bioenergetic costs of completing physical activity, is positively correlated with perceived distance. We also tested whether temporarily depleting bioenergetic resources through exercise would result in greater perceived distance. Eighty-two members of the public were recruited at a beach in Weston-super-Mare, UK. Half completed moderate exercise and half acted as controls. They then estimated distance to a set point. Results showed that RMR (computed using a recognized equation) was positively correlated with distance perception, meaning that participants requiring greater energy to traverse a set distance perceived the set point as farther away. In addition, those participants who had their bioenergetic resources temporarily depleted through exercise perceived the set distance as greater, compared to controls. There was no interaction effect between RMR and exercise. To our knowledge, these results are the first to show a relationship between metabolic rate and distance perception, and they contribute to the literature on embodied perception.

The Relative Nature of Perception: A Response to Cañal-Bruland and van der Kamp (2015)

Cañal-Bruland and van der Kamp present an argument about the incommensurate relationship between affordance perception and spatial perception in a criticism of Proffitt and Linkenauger’s phenotypic approach to perception. Many of their criticisms are based on a difference in the interpretation of the core ideas underlying the phenotypic approach. The most important of these differences in interpretations concern fundamental assumptions about the nature of the perceptions of size and distance themselves. Extent perception must be relative to the organism; therefore, there can be no veridical perception of space. Also, we argue in the phenotypic approach that space perception is an emergent property of affordance perception; they are not different types of perceptions as Cañal-Bruland and van der Kamp presume. Third, affordance perception need not be perfectly accurate, just good enough. Additionally, affordance perception need not be dichotomous; this presumption likely originates in the methodology typically employed to study affordance perception. Finally, I agree with Cañal-Bruland and van der Kamp that joint research efforts will clarify and improve our understanding of these issues.

Perceived distance and obesity: It's what you weigh, not what you think

Action abilities are constrained by physical body size and characteristics, which, according to the action-specific account of perception, should influence perceived space. We examined whether physical body size or beliefs about body size affect distance perception by taking advantage of naturally-occurring dissociations typical in people who are obese but believe themselves to weigh less. Normal weight, overweight, and obese individuals made verbal distance estimates. We also collected measures of beliefs about body size and measures of physical body size. Individuals who weighed more than others estimated distances to be farther. Furthermore, physical body weight influenced perceived distance but beliefs about body size did not. The results illustrate that whereas perception is influenced by physical characteristics, it is not influenced by beliefs. The results also have implications for perception as a contributing factor for lifestyle choices: people who weigh more than others may choose to perform less physically demanding actions not as a result of how they perceive their bodies, but as a result of how they perceive the environment.

Action-specific influences on perception and postperceptual processes: Present controversies and future directions

The action-specific perception account holds that people perceive the environment in terms of their ability to act in it. In this view, for example, decreased ability to climb a hill because of fatigue makes the hill visually appear to be steeper. Though influential, this account has not been universally accepted, and in fact a heated controversy has emerged. The opposing view holds that action capability has little or no influence on perception. Heretofore, the debate has been quite polarized, with efforts largely being focused on supporting one view and dismantling the other. We argue here that polarized debate can impede scientific progress and that the search for similarities between 2 sides of a debate can sharpen the theoretical focus of both sides and illuminate important avenues for future research. In this article, we present a synthetic review of this debate, drawing from the literatures of both approaches, to clarify both the surprising similarities and the core differences between them. We critically evaluate existing evidence, discuss possible mechanisms of action-specific effects, and make recommendations for future research. A primary focus of future work will involve not only the development of methods that guard against action-specific postperceptual effects but also development of concrete, well-constrained underlying mechanisms. The criteria for what constitutes acceptable control of postperceptual effects and what constitutes an appropriately specific mechanism vary between approaches, and bridging this gap is a central challenge for future research.

Summarizing slant perception with words and hands; an empirical alternative to correlations in Shaffer, McManama, Swank, Williams & Durgin (2014)

The paper by Shaffer, McManama, Swank, Williams & Durgin (2014) uses correlations between palm-board and verbal estimates of geographical slant to argue against dissociation of the two measures. This paper reports the correlations between the verbal, visual and palm-board measures of geographical slant used by Proffitt and co-workers as a counterpoint to the analyses presented by Shaffer and colleagues. The data are for slant perception of staircases in a station (N=269), a shopping mall (N=229) and a civic square (N=109). In all three studies, modest correlations between the palm-board matches and the verbal reports were obtained. Multiple-regression analyses of potential contributors to verbal reports, however, indicated no unique association between verbal and palm-board measures. Data from three further studies (combined N=528) also show no evidence of any relationship. Shared method variance between visual and palm-board matches could account for the modest association between palm-boards and verbal reports.