Nature benefits revisited: Differences in gait kinematics between nature and urban images disappear when image types are controlled for likeability

Abstract

Exposure to urban environments requires more cognitive processing than exposure to nature; an effect that can even be measured analysing gait kinematics whilst people walk towards photographic images. Here, we investigated whether differences in cognitive load between nature and urban scenes are still present when scenes are matched for their liking scores. Participants were exposed to images of nature and urban scenes that had been matched a priori for their liking scores by an independent participant sample (n = 300). Participants (N = 44) were either asked to memorise each image during walking or to rate each image for its visual discomfort after each walk. Irrespective of experimental task, liking score but not environment type predicted gait velocity. Moreover, subjective visual discomfort was predictive of gait velocity. The positive impact of nature described in the literature thus might, at least in part, be due to people’s aesthetic preferences for nature images.

The effect of image fractal properties and its interaction with visual discomfort on gait kinematics

“…Statistical analysis, including multi-level modelling, followed the same analysis steps as detailed in our previous publications 18 , 19 .…”

“…Based on effect sizes observed in our earlier studies 18 , 19 , forty participants (33 females, 7 males, mean age = 20 ± 3.02 SD years, aged between 18–33 years) took part in this study. They were randomly assigned to one of two groups: twenty participants to the visual discomfort rating group (16 females, 4 males, mean age = 21 years + − 3.95 SD, aged between 18 and 33) and the other twenty participants (17 females, 3 males, mean age = 19 years + − 3.95 SD, aged between 18 and 24 years) to the likeability rating group.…”

“…Automatic Identification of Markers was applied to the 3D motion capture raw data, in particular foot and hip markers in proprietary software (Qualisys Track Manager (QTM), Qualisys AB). The procedure of step detection and trial removal due to QTM missing data has been described in detail in earlier studies, see 18 , 19 . To base analysis on data with constant walking speed only, data were truncated to the middle of the run.…”

“…Using changes in basic gait kinematics, such as step length and velocity, as a measure of cognitive load, we have recently shown that the impact of environment type (nature vs. urban) on cognitive processing load does not require prolonged exposure to the respective environments but can be picked up over several seconds exposure on a trial-by-trial basis 18 , 19 : in line with expectations for increased cognitive load (see for a review 20 ), participants walked more slowly and with shorter steps toward urban scenes than toward nature scenes. This opens a new promising way to investigate individual visual aspects for their contribution to increased cognitive load for urban scenes or decreased cognitive load for nature scenes 8 , 9 .…”

“…1 ; for a detailed description of image types, see 35 and 31 ) with similar fractal properties to ensure that any changes in gait would generalise across image types. Further, to control for any stimulus material induced changes in aesthetic preference or visual discomfort that had been reported before to affect changes in gait kinematics 18 , 19 , participants were asked to rate each image for its visual discomfort (n = 20) or its likeability (n = 20).

Figure 1 Example of selected abstract images which were parametrically varied in their fractal dimension/D value; and from the right to left: High Dimension (HD) with amplitude spectrum slopes (alpha) of 0.8 and fractal dimensions between 1.75 and 1.90, Intermediate Upper Dimension (IUD) with amplitude spectrum slopes (alpha) of 1.2 and fractal dimensions between 1.50–1.65, Intermediate Lower Dimension (ILD) with amplitude spectrum slopes (alpha) of 1.6 and fractal dimensions between 1.25 and 1.40, and Low Dimension (LD) with amplitude spectrum slopes (alpha) of 2.0 and fractal dimensions between 1.0 and 1.15.

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