Motor Skills and Motor Games PDF

Motor Skills and Motor Games Sensory components of motor control Professor: PhD. Juan Pablo Rey Lopez [email protected] Catholic University of Murcia (UCAM) Number of credits: 4.5 ECTS. Timing unit: Firs...

Motor Skills and Motor Games Sensory components of motor control Professor: PhD. Juan Pablo Rey Lopez [email protected] Catholic University of Murcia (UCAM) Number of credits: 4.5 ECTS. Timing unit: First semester 2024/25  In the study of human sensory physiology, there are three main senses involved*: 1. Proprioception: Somatic sensory system 2. Touch: Somatic sensory system 3. Vision: Visual sensory system * Despite other senses are also important (auditory information is relevant is sports or to keep balance)  2. Touch - 1.1 Neural basis of touch - 1.2 The tactile feedback contributes to force and movement accuracy - 1.3 Neural basis of vision - 1.4 Central processing: visual fields - 1.5 Eye tracking research studies  1.1 Neural basis of touch Multiple types of mechanoreceptors allow for perception of different qualities of touch The Pacinian corpuscles are located deep in the dermis of the skin and are responsible for perception of vibration and deep pressure. Ruffini endings detect skin stretch and temperature and are also located within the dermis layer of the skin. The Meissner corpuscles are stimulated by skin motion (light touch) and are located in the epidermis layer. The Merkel cells are located at the border between the dermis and epidermis and are specialized to detect edges and points (touch). Each mechanoreceptor responds to a touch stimulus in a specific area of the skin, a region called the receptive field of the receptor. When the receptive field is touched, the mechanoreceptor will be activated. Merkel cells and Meissner corpuscles, both of which are located near the skin surface, have small recep/ve fields. Ruffini endings and Pacinian corpuscles, located deeper in the skin layers, have larger recep/ve fields than the Merkel cells and Meissner corpuscles. Recep/ve fields size and density also vary among different body regions. In regions like the fingers or lips, they are smaller and more dense than in regions like the back or leg. FINER SPACIAL RESOLUTION WITH LOCATING AND IDENTIFYING OBJECTS Larger receptive fields are not as precise as smaller receptive fields Tools like calipers or even a paperclip can be used to measure two-point discrimination. If the two points of the caliper feel like one point, they are both activating the same receptive field, indicating the receptive field is large. If, however, it is possible to perceive two separate points on the skin, then the calipers are activating two different receptive fields 1.2 Tac>le feedback contributes to force adjustments For example, see Nowak 2005. Imagine you forget your gloves in a very cold, windy day. You evaluate your force adjustment to hold a glass of water. Would you apply more or less force to hold the glass?  1.2 Tactile feedback contributes to movement accuracy For example, see Rabin and Gordon 2004. Indicate the percentage of errors observed in the right index finger when typing aPer using anesthesia in the same finger. It is larger or smaller the error when is compared to non-anestheRzed condiRons?  1.3 Neural basis of vision The cornea is the transparent, external part of the eye. It covers the pupil and the iris and is the first location of light refraction. The pupil is the opening in the iris that allows light to enter the eye. The iris is the colored portion of the eye that surrounds the pupil and along with local muscles can control the size of the pupil to allow for an appropriate amount of light to enter the eye. The lens is located behind the pupil and iris. The lens refracts light to focus images on the retina. Proper focusing requires the lens to stretch or relax, a process called accommodation.  The retina is the light-sensitive region in the back of the eye where the photoreceptors, the specialized cells that respond to light, are located. The retina covers the entire back portion of the eye, so it’s shaped like a bowl. In the middle of the bowl is the fovea, the region of highest visual acuity, meaning the area that can form the sharpest images. The optic nerve projects to the brain from the back of the eye, carrying information from the retinal cells. Where the optic nerve leaves, there are no photoreceptors since the axons from the neurons are coming together (optic disc). The photoreceptors are the specialized receptors that respond to light. There are two types of photoreceptors: rods and cones. Rods are more sensitive to light, making them primarily responsible for vision in low-lighting conditions like at night and peripheral vision. Cones are less sensitive to light and are most active in daylight conditions. The cones are also responsible for color vision. Temporal blindness  1.4 Visual fields The two eyes together can view the entire visual field, which is all the visual space we can see without moving our head or eyes.  Visual field classification 1) Based on what eye is capable of seeing  Visual field classifica>on 2) Based on unique visual space seeing with one eye or both eyes Monocular visual fields are viewed by only one eye and are located toward the periphery of the full visual field. The binocular visual field is viewed by both eyes and is located in the center of the full visual field.  THE ROLE OF VISION IN MOTOR CONTROL Researchers use a variety of techniques to study the role of vision in motor control. EYE TRACKING Method of recording eye motion and gaze location across time and task. The position of the eye is generally measured with the help of the pupil or iris center.  EYE MOVEMENT RECORDING Video-based eye trackers can determine the direction of gaze with a high degree of accuracy by measuring the position of the corneal reflection of an infrared light relative to the pupil. The structure of the eye limits high acuity vision to a small portion of the visual field (Fovea). Fixation: Period of time during which the eyes are fixed on a visual target (180-300 milliseconds). Saccades: Ballistic movements of the eye from one fixation to the next. During saccades, visual input is suppressed, so that when our eyes are making a saccade we are effectively blind. A typical reading saccade is small (a 2 degree rotation) and lasts about 30 milliseconds, while saccades in scene perception are generally larger (about 5 degrees of rotation) and last 40 to 50 milliseconds. Saccades are quick jumping movements the eye makes as it traverses from one location to the next. In between these saccades are fixations (represented by red circles). Fixations are periods of time when the eye is focused on a single point, such as a word in a sentence or object in a scene. These pauses allow the eyes to take in visual information. A. When reading, fixations progress from left to right (in English). Some words are skipped. A regression in reading is an eye movement to a previous region of the text. B. When viewing a scene, fixations generally focus on meaningful or visually salient parts of the image, and there is more variability in the direction and amplitude of saccades.  How do eye trackers work? Eye trackers shine some light source into the eye, usually an infrared light that is invisible to humans. This light produces a reflection on the cornea that is identified by the eye tracking software. The center of the pupil is also identified by the software. Then a calibration is performed, where the participant is instructed to look at a series of points at known locations on the screen. If the calibration is good, the point of gaze (where the participant is looking) can then be estimated with a high degree of accuracy from the relative positions of the pupil and corneal reflection.  The two most prominent manufacturers are Tobii (https://www.tobii.com/) and SR Research (https://www.sr- research.com/) Trackers vary in their speed of data acquisition. The sampling rate of an eye tracker is measured in Hertz (Hz). The fastest commercial eye trackers record eye position up to 2000 times per second (2000 Hz), while wearable eye tracking glasses might only sample 50 times per second (50 Hz). Some trackers require that the head be stabilized via a chin rest, while for others the head is unsupported. Increased mobility means decreased precision and accuracy (more problematic to study children). Some trackers follow both eyes, while others track only one (and still others can be configured to track one or two eyes). As the eyes move together under most circumstances, tracking both eyes is typically not essential.  Ensuring data quality Eye tracking data is accurate if the measured eye position corresponds to the actual eye position, while eye tracking data is precise if it provides consistent measurements of eye position. These two terms are closely analogous to the broader concepts of validity and reliability, respectively. Eye tracker manufacturers provide accuracy and precision information about their devices. However, these values represent a best case scenario. If the infrared light is not getting to the eye in sufficient quantity, tracking will not work well. This can occur if a participant is wearing eyeglasses with a strong prescription or if the glasses are dirty or have a tint or an anti-glare coating. Another barrier is dark eye lashes (or eye lashes darkened by makeup), that the camera might mistakenly assign as part of the pupil.  Eye tracking raw data Eye tracking data is a series of samples. Each sample contains the point of gaze estimate for one or both eyes as an x and y screen position in pixels. The raw sample data is processed to identify fixations, saccades, lost data (automatically using eye tracking softwares or open access packages). Most eye tracking software allows the user to pre-define regions of interest to know how long or how often participants looked at a particular part of a stimulus, such as a particular word in a sentence, an object in a scene, or the eyes of a face.  Current limita,ons of mobile eye-tracking studies on natural gaze behavior in sports Only 31 studies included mobile eye-tracking to study gaze behaviour in sports. Relatively small samples in all studies. Low sample rate (30-60 Hz, average) Data reported in each study do not follow the best standards of quality. Eye-tracking technology and the dynamics of natural gaze behavior in sports: an update 2016–2022 Ralf Kredel et al. Eye tracking in high-performance sports: Evaluation of its application in expert athletes Hüttermann et al. 1) Most eye tracking studies have been conducted in the LAB “the current state of research does not allow for genuine and valid statements regarding the gaze behavior of expert athletes in many sports, respectively sport situations”. 2) The majority of eye tracking studies on high-performance sports has been carried out in the area of ball games area of ball games, it is important to consider that solely the gaze behavior in dead ball situations, i.e. when the ball is not in motion, has been analyzed. 3) Results revealed that the majority of published eye tracking research in the context of high-performance sports has compared gaze behavior between expert athletes and novices. However, different findings have demonstrated that these two groups differ in their gaze behavior (e.g., Williams et al., 1999) and that results from inexperienced sportswomen/sportsmen can hardly be used to inform on high-performance sports.  See the Review: “The Quiet Eye in Sports Performance—Is the Quiet Eye the Ultimate Explanation or Only the Beginning?” Dalton, Kristine *Define the quiet eye. * Is the quiet eye different between expert golfers and non-experts?  Expert athletes tend to use fewer fixations of longer duration including prolonged quiet eye periods than novices.