Brain imaging studies provide strong evidence for the involvement of the body's mirror system in observing complex movements (Calvo-Merino et al., 2005). Guillot and Collet (2005) showed that imagining a movement seems to preserve the spatial and temporal characteristics and to be based on the same cognitive and neural systems of the actual movement. In a MR task, participants are asked to identify as fast as possible whether two misoriented images represent the same or mirrored object. The decision time was shown to linearly increase as a function of the angular disparity between the two images (Shepard and Metzler (1971). Later, some authors used images of body parts (i.e., hand or foot) in MR tasks and asked participants to judge whether the image depicted a right or left body part (i.e., laterality judgment). The results revealed that reaction times were affected by the biomechanical constraints of the real body parts movements (Sekiyama, 1982). These findings suggest that participants imagine their own body part moving until alignment with the position of the stimulus (Moreau, 2012, 2013). Similarly, studies using depictions of human bodies with one arm outstretched revealed that the time to judge which arm is outstretched (i.e., laterality judgment) is dramatically affected by extreme (i.e., upside-down) body positions (Steggemann et al., 2011). Hence, mental body rotation tasks seem to imply embodied motor strategies requiring cognitive processing to transform participants’ own mental body representations to solve the task (Habacha et al., 2022; Khalfallah et al., 2022; Steggemann et al., 2011). That is, MR of a bodily stimuli involves cognitive processes used for both motor imagery and motor execution (Kawasaki & Higuchi, 2013).
Sport practice is an ideal context to develop spatial capacities, in particular visualization, orientation, and MR (Calvo-Merino et al., 2005; Pietsch & Jansen, 2012). During sport practice, the cognitive mechanisms underlying a movement play a key role in its improvement, considering the functional equivalence between actual and imagined skills (Decety, 2002). Moreau et al. (2012) and Pietsch and Jansen (2012) proved great effects of motor training on mental rotation performance.
Additionally, athletes with different abilities in different sports appear to use different strategies to solve the same mental rotation tasks. Accordingly, the specific sensorimotor experiences seem to shape the cognitive processing during these tasks (Habacha et al., 2017; Habacha et al., 2022; Steggemann et al., 2011). These findings support the involvement of motor processes in MR (Jansen & Lehmann, 2013) and further refine the established equivalence between actual and covert movement, thereby providing new perspectives for designing tasks aimed at mental imagery training for the development of motor execution.
Furthermore, it has been shown that physical activity, especially a balance training program, improves memory and spatial awareness (Rogge et al., 2017). Rogge et al. (2017) compared the balance and cardiorespiratory fitness of two groups with and without 12 weeks of balance training. Only participants who followed the training significantly improved their balance, memory, and spatial awareness. The researchers explain that stimulation of the vestibular system during balance training could have induced changes in the hippocampus and parietal cortex, possibly through direct pathways between the vestibular system and these brain regions (Rogge et al., 2017). Bigelow and Agrawal (2015) showed a link between vestibular function and cognitive domains of visuospatial ability, including spatial memory, navigation, MR, and mental representation of three-dimensional space. Hofmann and Jansen (2021) investigated the relationship between MR and postural stability by examining the effects of performing an egocentric (i.e., bodily stimuli) and object-based (i.e., abstract stimuli) MR task simultaneously with stabilized postural sway in a tense position with both legs on a stable surface (i.e., a force plate). Their results showed that the egocentric task involved more body swaying than the object-based task. These results suggest that the egocentric mental rotation task involved more kinaesthetic imagery and motor processes in that subjects had to imagine rotating their own bodies’ mental representations (Kessler & Rutherford, 2010), whereas the object-based task involves mostly visual processes that are not affected by the kinaesthetic body representations (Hofmann & Jansen, 2021). Furthermore, increasing the rotation angle of the stimuli in the MR task resulted in more body sway (Hofmann et al., 2022), confirming the involvement of motor processes. Pellecchia (2003) corroborated this finding by revealing that more body sway may be due to increased difficulty of concurrent cognitive tasks.
However, not all athletes automatically engage motor processes during MR of bodily stimuli, resulting in contradictory results. Participation in certain sports, such as wrestling, seem to favour motor-based strategies to outperform other athletes or non-athletes, even if abstract objects are used in MR (Moreau et al., 2012; Pietsch et al., 2019). Furthermore, athletes who’s sports require more visuospatial and kinaesthetic abilities linked to real body rotations, such as wrestlers and gymnasts, show better performance in MR of bodily stimuli than athletes who practice cardiovascular activities such as running (Moreau et al., 2012; Schmidt et al., 2016). In contrast, team sports encourage the use of visual strategies, as athletes are trained to perceive and analyse moving objects and examine spatial relationships with partners and opponents from off-centre perspectives (Steggemann et al., 2011).
Moreover, athletes participating team sports and racquet sports showed significantly shorter reaction times (i.e., go / no-go) than those in other sports (Dogan, 2009; Erickson, 2020). Delpont et al. (1991) observed faster transmission in the visual pathway in tennis and squash players compared to rowers and non-athlete controls. That is, team sports and racquet sports, which require rapid visual activity, seem to enhance the development of information processing and mental rotational performance. However, other studies have shown that elite team athletes do not exhibit better mental rotational performance of bodily and abstract figures compared to non-athletes (Heppe et al., 2016; Jansen et al., 2012).
One way to provide new insight to these contradictory results is to compare performance of badminton and volleyball players in MR of bodily stimuli in different upright conditions (i.e., with and without dynamic balance). The effect of balance on MR performance in one group and not the other would help understand the processes engaged in the task.
We hypothesized that the dynamic balance condition will have immediate beneficial effects on the MR task by decreasing response time for both badminton and volleyball players. Secondly, badminton players will be more able and faster than volleyball players to recognize the correct response of rotated body images, given that the shuttlecock in badminton travels at a much faster and less predictable trajectory than the ball in volleyball.