Master of Kinesiology (MKin)
Faculty of Science
Dr. Michael Cinelli
Individuals use visual information in order to guide their avoidance behaviours. More specifically, individuals may directly perceive the time prior to colliding with an approaching obstacle (i.e., time to contact, TTC) in order to determine when to avoid. However, if the path of the approaching obstacle is highly predictable, individuals do not use a consistent TTC (Cinelli & Patla, 2007). Additionally, individuals use body- and action-scaled information to control their movements (Fajen, 2013). These avoidance behaviours differ when avoiding a human obstacle compared to an inanimate object (Hackney, Cinelli, & Frank, 2015; Knowles, Kreuser, Haas, Hyde, & Schuchart, 1976). As such, the purpose of this thesis was to examine the avoidance behaviours of individuals during a head-on collision course with an approaching person. This task assessed steering strategies in a confined environment while individuals avoided an approaching person who walked along one of four randomized paths. Avoidance behaviours were compared between males and females (Study 1), and female rugby players versus female non-athletes (Study 2) to assess the potential differences in the use of body-scaled and action-scaled information during the same paradigm. Specifically, the objectives of the current thesis aimed to examine (1) how young adults control their actions and (2) the effects of sport-specific training on avoidance behaviours of rugby players during a collision course with an approaching person. Young adults (N=20, = 22.25 ± 1.5 years, 10 males) and female rugby players (N=10, = 20 ± 0.94 years) were instructed to walk along a 10m path towards a goal located along the midline. A female confederate positioned initially along the midline 180° from the participant walked towards the participants to one of four predetermined final positions: 1) along the midline in the participants’ starting position; 2) stopped along the midline 2.5 m from her starting position; 3) to the left of the participants’ starting position; and 4) to the right of the participants’ starting position. Results from both studies revealed that when the path of the confederate was uncertain, individuals used a consistent TTC to determine when to change their path. TTC described the temporal distance between the confederate and the participant at the point of a change in path of the participant. TTC was found to be affected by sex and sports specific training, such that males avoided significantly earlier (i.e. larger TTC) and rugby players avoided significantly later (i.e. smaller TTC) than non-athlete females. However, following a change in path, sex and sport-specific training did not impact the avoidance behaviours of the groups, but rather the environment was the regulating factor. Avoidance strategies differed when the confederate stopped 2.5 m from her starting position from the other path conditions. When avoiding the stopped confederate, individuals avoided earlier (i.e. larger TTC), at a slower rate, and to a lesser magnitude. This suggests individuals may have selected their strategies based on comfort. More specifically, when the confederate stopped 2.5 m from her starting position, the decrease in uncertainty of her movement may have allowed for more comfortable, self-paced avoidance. However, during the conditions in which the confederate’s path was highly uncertain, individuals did not use a single avoidance strategy, instead their behaviours were based on the relationship between the environment and the observer (i.e. sex and sport-specific training).
Pfaff, Lana M., "The Sidewalk Problem: An examination of the avoidance behaviours employed during a head-on collision course with an approaching person" (2018). Theses and Dissertations (Comprehensive). 2039.
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