Flexible perception-action strategies:The influence of segmental and global motion information on follow-the-leader coordination

Interpersonal coordination in sports can be studied by examining interactions between agents. Evidently, individuals differ in their ability to interact with others (cf. ‘interact-ability’), which critically depends on their sensitivity to information for (inter-)action. Recently, we found that agents could access different information sources for the same task goal, yet it subtly affected temporal and spatial aspects of the interactive synchrony. The current study further examined what strategies agents adopt to deal with different types of information. Participants performed a follow-the-leader task in a virtual reality setting in several conditions. In the reference condition, a leader was presented as a back-and-forth walking animated avatar. In the other conditions, various aspects of motion information were either suppressed or emphasized. We emphasized movement of body segments using a point-light display. In other conditions we showed a mannequin (i.e. an avatar without moving limbs) with various combinations of the subtle, but potentially pertinent, lateral and vertical displacements that occur during gait. Another set of conditions showed different shapes (a mannequin, cylinder and sphere) that only displayed the optical size change corresponding to the back-and-forth displacement. Point-estimate relative phase revealed a tighter temporal synchrony when movements of body segments were shown. In contrast the virtual interpersonal distance was best maintained when only optical size change was displayed. These findings support the notion that a perception-action strategy is strongly shaped by its dynamic environment. Different skill levels of adopting such flexible behaviour may explain an individual’s interact-ability.