According to different authors, there are basically two dissimilar views about speed perception. Some argue that it is the estimate of distance and time of motion based on two parameters: distance extension and motion duration. Others claim that speed is a sensation not related to distance or time. Perhaps, both views have a relationship as it would be a sensation of motion induced by time and distance.
In skiing, visual and auditory information is processed by visual and auditory cortices complemented to perceive motion speed. Noise (air turbulence, the sound of the edges scraping, etc.) influences speed perception enhancing it; on the contrary, listening to music disturbs it.
According to Brunner et al. (2015), speed perception in skiing depends on gender, technical level, and risk-taking behavior. Men, skiers with better technical level, and risky skiers perceive their speed as fast compared to women, less skilled, and cautious skiers.
Ruedl et al. (2013) suggest that recreational skiers underestimate their speed and men, good skiers, skiers who take greater risks, and young skiers show a better ability to estimate their skiing speed. The same study determined that skiers that ski up to 30 km per hour tend to overestimate their speed, while skiers exceeding that limit are prone to underestimate it.
It is observed, in some skiers, a common behavior that is skiing fast just as they had assimilated the basic technical elements. Actually, at this level, speed does not need to be trained since we usually learn to ski faster if our technique improves. For the beginner, speed is an inconvenience, for the expert a benefit, and for the racer an advantage.
Speed perception while skiing depends also on the influence of certain variables. If we descend at a constant speed near an aligned row of poles or trees, we will perceive greater speed if the space between these poles or trees decreases, and vice versa if the separation between them increases. This is why on roads there are textured white lines with gradual narrowing of the space between them before reaching specific places, so we perceive that we must decrease our speed.
Other variables in speed perception are the distance to the surface, because of the optic flow, speed is perceived as increasing if our posture gets closer to the snow and also, that speed perception is greater if we are accelerating.
In terms of speed maintenance, it is observed that, due to the lack of experience in speed and path control, beginners and low intermediate skiers tend to decrease their speed at the moment of turning, accelerating along the linear trajectory between turns, while experts tend to keep constant speed most of the time.
Speed and precision
In general, skiing fast induces less precision or, in other words, increasing our skiing speed decreases our actions’ accuracy. While learning to ski, it is observed that the beginner seeks to favor speed control over precision. In most cases, the recreational skier prioritizes a certain balance between speed and precision in the same way the racer does, but in particular situations, he prioritizes precision and in others favors speed.
During ski learning, the best choice would be finding an optimum relationship between speed and movement precision. While skiing slowly, we pick up information with more details but at faster speeds, even if we perceive motion better, our visual detection of the environment layout decreases.
Factors influencing speed perception
Skiing speed perception depends on the following:
- Visual and auditory information.
- Experience
- Weather factors such as light contrast.
- Slope configuration and conditions such as fixed obstacles and traffic.
Slope configuration affects speed perception. If it is wide, straight, with uniform inclination, good light contrast, and low traffic level; we are prone to greater speed. Instead, if the snow surface is irregular, which increases vibration, we tend to decrease our speed.
According to the slopes’ usable space, if it increases we do the same in terms of our speed. An environmental factor influencing speed perception is having trees on one or both sides of the slope. The lamellar flow we perceive in the retina while skiing near trees makes us judge faster motion so we tend to decrease our speed. On the opposite, on a slope without trees, as we are prone to underestimate safety, we tend to increase our speed. Before a drop-off we cannot detect the after tilt degree, so we tend to slow down or stop.
Ice and hard snow produce non-pleasant auditory and haptic information, inducing us to speed decreasing. In low contrast conditions like mist, fog, flat light, or white-outs, our speed perception is reduced while skiing on an uneven surface increases it. The behavior of others could also influence our speed perception. If we are skiing within a group, our own speed may be influenced by the speed of the other skiers.
In conclusion, we can assume that the factors influencing our speed perception when skiing are:
- The increase of the focus of expansion.
- The intensity of the ground’s optic flow.
- The intensity of the lamellar flow in enclosed environments (skiing in the woods, intense traffic flow areas).
- Snow texture and/or ground irregularity.
- Noise generated by our sliding motion.
- The intensity of vibrations.
- Our own subjective perception.
