Browsing by Author "Wagman, Jeffrey"
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Item APAL "Sensitivity to changes in dynamic affordances for walking on land and at sea" Data Sets(2019-09-17) Walter, Hannah; Li, Ruixuan; Peterson, Nicolette; Stoffregen, Thomas; Wagman, Jeffrey; walte666@umn.edu; Walter, Hannah; University of Minnesota Affordance Perception-Action LabWe investigated the perception of affordances for walking along a narrow path. We asked whether participants could perceive changes in affordances brought about by manipulation of properties of the body, or of the environment, without direct practice of the to-be-perceived affordance, and without external feedback about the accuracy of perception. In Experiment 1, participants made a series of 8 judgments of how far they could walk along a narrow path either, 1) without added weight, 2) while wearing a weighted vest, or 3) while wearing weights on their ankles. Before walking, mean judgments were lower when wearing weights than in the no-weight condition. In addition, in both weight conditions judgments changed across the series of 8 judgments, in the direction of greater accuracy. Control of the body in walking also can be influenced by motion of the ground surface, as commonly happens in vehicles. In Experiment 2, on a ship at sea, we evaluated the effects of walking with or without weight added to the body at the ankles. We again asked participants (experienced maritime crewmembers) to judge how far they could walk along a narrow path, with versus without ankle weights. As in Experiment 1, judgments made before walking mirrored the observed differences in walking performance. In addition, we again found evidence that judgment improved (without walking practice, or feedback) over the series of judgments. We conclude that participants were sensitive to (and spontaneously learned about) how affordances for walking were influenced by changes in the dynamics of body and the environment.Item Dataset with the variables analyzed in the study: "Perception of affordances in female volleyball players: serving short versus serving to the sideline"(2023-04-05) Arruda, Danilo G; Barp, Fabio; Felisberto, Greysian; Tkak, Claudio; Wagman, Jeffrey; Stoffregen, Thomas; arrud005@umn.edu; Arruda, Danilo G; ; Affordance Perception-Action LaboratoryPurpose: We investigated youth volleyball players’ perception of affordances for different types of serves. Method: Participants were separated into Less Experienced (n = 13, maximum of three years of competitive volleyball experience) and More Experienced (n = 11, minimum of four years of competitive volleyball experience) groups. In the Sideline Condition, participants were asked to report the narrowest gap, relative to either the left or right sideline, into which they could serve the ball. In the Short Condition, participants were asked to report the narrowest gap, relative to the net, into which they could serve the ball. Participants then attempted to serve into their reported gaps. Results: As expected, reported serveable gaps were larger for the Short Serve condition (M = 3.66 m, SD = 0.67 m) than for the Sideline Serve condition (M = 1.93 m, SD = 0.71 m), F(1, 22) = 80.45, p < .001, partial η2= 0.79. The proportion of successful serves was greater for the More Experienced group than for the Less Experienced group, but a statistically significant interaction revealed that this was true only when performing sideline serves. Conclusions: Our study extends previous work to a different sport (volleyball) and to different sport-specific actions (serving the ball). The finding that perceived minimum servable gap sizes were larger for short serves than for sideline serves is consistent with differences in the constraints operating on the two types of serves in the context of game play.Item RV Atlantis 2019 Ship Data(2019-01-25) Walter, Hannah; Li, Ruixuan; Stoffregen, Thomas; Wagman, Jeffrey; walte666@umn.edu; Walter, Hannah, J.Ocean waves cause oscillatory motion of ships. Oscillatory ship motion typically is greater in roll (i.e., the ship rolling from side to side) than in pitch (i.e., tipping from front to back). Affordances for walking on a ship at sea should be differentially influenced by ship motion in roll and pitch. When roll exceeds pitch, the maximum walkable distance within a defined path should be greater when walking along the ship’s short, or athwart axis than when walking along its long, or fore-aft axis. When pitch exceeds roll, this relation should be reversed. We asked whether such changes in ship motion would be reflected in judgments of direction-specific affordances for walking. Participants (experienced maritime crewmembers) judged how far they could walk along a narrow path on the ship deck. On different days, sailing conditions were such that the relative magnitude of pitch and roll was reversed. Judgments of direction-specific affordances for walking mirrored these changes in ship motion. The accuracy of judgments was consistent across directions, and across changes in ship motion. We conclude that experienced maritime crewmembers were sensitive to dynamic variations in affordances for walking that were, themselves, a function of dynamic properties of the animal-environment system.