The relationship between visual field dependent and independent skiers in skidding situations
Vestibular and kinesthetic information provide signals that we use to regulate our skidding. While visual information is essential, to skid our ski tails do not provide appropriate visual feedback. Usually, in this situation, we tend to tilt our body towards the opposite side of the skidding direction, creating an upright posture perception change. According to the characteristics of the visual field-dependent skiers, we may take longer to adjust our body tilt, while being visual field-independent skiers, which we take advantage of vestibular and proprioceptive information, we tend to quickly correct our body tilting.
Visual perception of other people’s motion
The perception we have about the trajectory of others is based on our global vision of their motions and our local vision coming from the relationship between their motions compared with fixed objects in the slope. In crowded slope situations or in surpassing others, our visual fixations tend to reduce in duration and increase in quantity.
Differences in visual perception of motion in beginner and expert skiers
The beginner skier tends to focus his gaze on smaller areas, looking forward with less skill in the use of peripheral vision while the expert makes better use of a broader angle of horizontal visual search.
The beginner fixes his gaze longer in risky situations and the expert does it for less time, changing the fixating point more often. It can be given the situation that, due to experience, the expert applies less cognitive load picking up visual information of the environment, then he can also direct his gaze to irrelevant objects or situations.
The beginner does not know precisely where or what to look at, so he is prone to explore the slope with his central vision. With practice, he will use peripheral vision to visual field limits and central vision to guide his trajectories. Facing a novel visual situation, he will take longer to process it than the expert. Besides, at controlling his own path, the beginner provides visual attention to control his skis, while the expert dedicates it exclusively to trajectory choice and other more relevant aspects. Moreover, the beginner has more ocular pursuit frequency to detect others, i.e., tends to follow them with his gaze longer than the expert.
The beginner’s visual fixation time is longer due to unfamiliar environment conditions, to the limitation of his attention, and to the lack of automation. In addition, processing slope and traffic conditions demand more time for him. He also has a propensity to control his motion focusing the ground optic flow and, with time, will learn to better self-locate by directing his gaze towards the focus of expansion.
Lastly, the expert detects potential hazards more effectively. We can conclude that the beginner points out his eyes (simple visual fixation) whereas the expert guides his gaze consciously (attentive visual fixation).
Visual perception of rectilinear and curvilinear motion
While moving in a linear path, our vision is aligned with the focus of expansion, which provides an orientation reference. When changing direction, the focus of expansion is altered because the initial disposition of our skis is misaligned in relation to it.
In addition, if the arc of our curvilinear trajectory is not constant, we must monitor it regarding the preset direction change point. Generally, our visual fixations are longer in linear motion and shorter and successive in curvilinear trajectories.
Visual perception of motion in reduced visibility conditions
In poor visibility conditions, in which our vision is limited, it is important to develop sensory skills to compensate for our visual decrease. Total visual dependency is not appropriate in low visibility situations, and this is why it is significant to utilize varied sensory information and thus be able to rely on another source when we are not exploited, otherwise, our performance will diminish.
Perception of distance
During motion, we perceive distance using environmental information as the following:
- The size of objects (bigger objects are perceived closer).
- Visual acuity (distant objects are seeing blurrier).
- Superposition (a whole object is perceived closer than one overlapped behind another or appearing just partially).
- Ground surface (the farther away, the more regular it seems).
- Snow texture (the closer, the more details are observed).
In distance perception, according to the atmospheric perspective, as air is not fully transparent, when looking far away the layers of air accumulates distorting light waves, then distant objects often appear fuzzy.
If we take the horizon line as a reference, an object located close to this line will be perceived remote and to the contrary, when the object is further away from that line we will perceive it closer.
