Article

Minimum Predicted Distance: applying a common metric to collision avoidance strategies between children and adult walkers

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Abstract

Background Collision avoidance between two walkers involves a mutual adaptation to speed and orientation in order to successfully avoid a collision. Minimum Predicted Distance (MPD) is the distance at which two walkers would collide if their speed and path trajectory were maintained at first sight of one another. MPD has been used to describe the risk of collision and its evolution over time between two adult walkers when on a collision course. Middle-aged children have been shown to have poor perception-action coupling during static and dynamic collision avoidance tasks. Research has yet to examine whether perception-action coupling deficits persist in a dynamic collision avoidance task involving a child and another walker. Research Question Can the metric MPD(t) be used to examine collision avoidance strategies between children and adults? Methods Eighteen children (age: 10 ± 1.5 years) and eighteen adults (34 ± 9.6 years) walked along a 12.6 m pathway while avoiding another participant (child or adult). Groups of three children and three adults were recruited per session. Trials were randomized equally such that each adult interacted with another adult 20 times, each child interacted with another child 20 times, and each adult interacted with a child 21 times, for a total of 141 trials. 3D kinematic data of each participant’s head was recorded using the Vicon system. Results The results demonstrated: (1) MPD(t) can be used to predict future collisions in children, (2) MPD(t) is an absolute measure that is consistently lower when a child is involved compared to two adult walkers, (3) the individual passing second, even when it is a child, contributes more to MPD(t) than the walker passing first. Significance It appears children have developed adult-like strategies during a collision avoidance task involving two walkers. Body anthropometrics should be considered when determining collision avoidance strategies between children and adults.

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... The mutual avoidance between two pedestrians during a 90°-collision avoidance task can be described using the evolution of Minimum Predicted Distance (mpd), which predicts the future risk of collisions between two walkers [17][18]. In such as task, role-dependent strategies can be identified based on crossing order such that, the walker passing second contributes more to the avoidance situation compared to the walker passing first, regardless of age [18][19]. These roledependent strategies are established at the initial sight of one another and are maintained throughout the entirety of the avoidance task such that, the walker who is intended to pass first at the beginning of the interaction (based on walkers' respective velocity and position) is the one who passes first at the time of crossing [18,21]. ...
... These roledependent strategies are established at the initial sight of one another and are maintained throughout the entirety of the avoidance task such that, the walker who is intended to pass first at the beginning of the interaction (based on walkers' respective velocity and position) is the one who passes first at the time of crossing [18,21]. This 90-collision avoidance task and mpd analyses has proved to be an effective paradigm to quantify avoidance behaviours (i.e., contribution to avoidance, role identification to the avoidance, and temporal evolution of an avoidance) across the lifespan, highlighting visuomotor changes due to development and aging [19][20]. ...
... Minimum Predicted Distance (mpd), was analyzed as a function of time throughout the interaction period to examine contribution to collision avoidance between athletes. Comparing initial response to collision avoidance, the threshold for motion adaptation between two control athletes (ATH-ATH) was similar to previous findings in young adults (~1m) [17][18][19][20]. However, when two CONC interacted (CONC-CONC), risker collision avoidance strategies manifested in a smaller adaptation threshold (0.84m). ...
Article
Background Individuals who have sustained a concussion often display associated balance control deficits and visuomotor impairments despite being cleared by a physician to return to sport. Such visuomotor impairments can be highlighted in collision avoidance tasks that involves a mutual adaptation between two walkers. However, studies have yet to challenged athletes with a previous concussion during an everyday collision avoidance task, following return to sport. Research Question Do athletes with a previous concussion display associated behavioural changes during a 90°-collision avoidance task with an approaching pedestrian? Methods Thirteen athletes (ATH; 9 females, 23±4years) and 13 athletes with a previous concussion (CONC; 9 females, 22±3 years, concussion <6 months) walked at a comfortable walking speed along a 12.6 m pathway while avoiding another athlete on a 90º-collision course. Each participant randomly interacted with individuals from the same group 20 times and interacted with individuals from the opposite group 21 times. Minimum predicted distance (mpd) was used to examine collision avoidance behaviours between ATH and CONC groups. Results The overall progression of mpd(t) did not differ between groups (p>.05). During the collision avoidance task, previously concussed athletes contributed less when passing second compared to their peers(p<.001). When two previously concussed athletes were on a collision course, there was a greater amount of variability resulting in inappropriate adaptive behaviours. Significance Although successful at avoiding a collision with an approaching athlete, previously concussed athletes exhibit behavioural changes manifesting in riskier behaviours. The current findings suggest that previously concussed athletes possess behavioural changes even after being cleared to returned to sport, which may increase their risk of a subsequent injury when playing.
... Although there has been an interest in examining person-person interactions, these studies have traditionally examined behaviours during different situation-specific scenarios, such as mutual or joint-task avoidance (Creem-Regehr et al., 2013;Knorr et al., 2016;Olivier et al., 2013;Rapos et al., 2019), passing through apertures (Davis et al., 2010;Hackney et al., 2015), and interacting on various angles (Cinelli & Patla, 2008;Huber et al., 2014;Kozlowski & Cutting, 1977;Olivier et al., 2013;Pfaff & Cinelli, 2018). Person-person studies have focussed on collision avoidance and aperture crossing tasks with two mutually-independent walkers (Creem-Regehr et al., 2013;Davis et al., 2010;Knorr et al., 2016;Olivier et al., 2013;Rapos et al., 2019) and have found situational effects on behaviour such as speed, heading direction, and crossing order on spatial and temporal parameters of avoidance. ...
... Although there has been an interest in examining person-person interactions, these studies have traditionally examined behaviours during different situation-specific scenarios, such as mutual or joint-task avoidance (Creem-Regehr et al., 2013;Knorr et al., 2016;Olivier et al., 2013;Rapos et al., 2019), passing through apertures (Davis et al., 2010;Hackney et al., 2015), and interacting on various angles (Cinelli & Patla, 2008;Huber et al., 2014;Kozlowski & Cutting, 1977;Olivier et al., 2013;Pfaff & Cinelli, 2018). Person-person studies have focussed on collision avoidance and aperture crossing tasks with two mutually-independent walkers (Creem-Regehr et al., 2013;Davis et al., 2010;Knorr et al., 2016;Olivier et al., 2013;Rapos et al., 2019) and have found situational effects on behaviour such as speed, heading direction, and crossing order on spatial and temporal parameters of avoidance. Furthermore, studies have examined how individuals adjust for the affordances and action capabilities of others (Creem-Regehr et al., 2013;Davis et al., 2010;Knowles et al., 1976), attaching greater intentionality and the potential for movement to large groups of people compared to a single person (Knowles et al., 1976). ...
Article
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Article
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Effect if virtual human gaze behaviour during an orthogonal collision avoidance walking task
  • S Lynch
S. Lynch, Effect if virtual human gaze behaviour during an orthogonal collision avoidance walking task, IEEE Virtual Reality, Conference Paper, (2018).