Nautical Affordances for Walking

Abstract

I investigated the perception of affordance that emerge from dynamic aspects of humans (lateral oscillations of the body during walking) and the environment (angular motion of the ground). I chose to focus on the ways in which motion of ships at sea may influence how humans detect their affordances. Humans going out to sea for thousands of years, yet very little research has addressed perception and action at sea. I conducted several affordance experiments at sea to begin filling the large gap in human movement literature. I chose to investigate the affordance of walking on the deck within the confines of a pathway. In Experiment 1, I asked seasoned mariners to estimate their ability to walk within a set pathway. Upon completion of these judgments, the mariners were then asked to perform the walking task. The results showed that mariners’ judgments were accurate. In Experiment 2, I built off of this success, repeating the same design across daily changes in ship angular motion. Judgments accurately reflected these daily changes. Finally, in Experiments 3 and 4, I took a different approach. While the two previous experiments utilized the natural ship motion (environmental factor) to change the affordance, in Experiments 3 and 4 I used weights added to the participant (animal factor) to manipulate affordances for walking. I first established that added weight influenced affordance judgments on land. I then found similar effects on a ship at sea. Taken together, my experiments expand our understanding of perceptual sensitivity to affordances that arise from dynamic properties in the animal-environment system. Additionally, many implications concerning nautical performance and safety can be gleaned from this study.