Exploration of the effect of EEG Levels in experienced archers

13 Pages·2017·0.44 MB·English

by  Caroline Fixter

Exploration of the effect of EEG Levels in experienced
archers
TWIGG, Peter, SIGURNJAK, Stephen, SOUTHALL, Dave and SHENFIELD,
Alex <http://orcid.org/0000-0002-2931-8077>
Available from Sheffield Hallam University Research Archive (SHURA) at:
http://shura.shu.ac.uk/8307/
This document is the author deposited version. You are advised to consult the
publisher's version if you wish to cite from it.
Published version
TWIGG, Peter, SIGURNJAK, Stephen, SOUTHALL, Dave and SHENFIELD, Alex
(2014). Exploration of the effect of EEG Levels in experienced archers.
Measurement and Control, 47 (6), 185-190.
Copyright and re-use policy
See http://shura.shu.ac.uk/information.html
Sheffield Hallam University Research Archive
http://shura.shu.ac.uk
Measurement and Control

Exploration of the Effect of EEG Levels in Experienced
Archers

Journal: Measurement and Control
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Manuscript ID: MAC-13-0003.R1
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Manuscript Type: Original Paper
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Date Submitted by the Author: 1 5-May-2014
Complete List of Authors: Twigg, Peter; Manchester Metropolitan University, School of Engineering
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Sigurnjak, Stephen; Manchester Metropolitan University, School of
Engineering
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Southall, Dave; Manchester Metropolitan University, School of Engineering
Shenfield, Alex; Sheffield Hallam University, Engineering
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Keywords: EEG, Archery, Brrainwaves

This preliminary study aims to record the brainwaves of two experienced
archers, whist undertaking the process of aiming and shooting arrows at a
target. The brainwavRes are then analysed for repeatability and dominant
Abstract:
characteristics within individual EEG activity. Images of the archers are
also recorded to establishe reference points within the shot cycle for
correlating the EEG data sets.
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Page 1 of 11 Measurement and Control
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10 1. Introduction
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Archery is a sport, which has increased in popularity since the London 2012 Olympic
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Games. It is now an Olympic core event and has recently seen its Olympic funding
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15 increase from group D for London 2012 to group C for Rio 2016. This highlights the
16 sport’s popularity.
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Archery involves the coordination of the muscular and skeletal system to provide a
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repeatable pattern whilst under loading during the drawing, aiming and release of the
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21 arrow. The hold ando aim phase of the shot are of particular importance. At this time, the
22 archer must resist the wreight of the bow (both the physical weight of the bow in the
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hand and the draw weight) whist aiming at the target and expanding until the release of
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25 the string. Within this criticaPl point of the cycle the archer is processing visual
26 information with regards to the position of the sight on the target as well as maintaining
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motion prior to release.
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The aiming process and the visual relationship is also noted within basketball; when an
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31 experienced player throws a ball to the ho op the player first fixates on the target but
32 then as the aiming action is performed the vision is suppressed [1].
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The brain is very much like a computer system, using brain cells to transmit messages
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to one another in order for us to function; these signals are well known as brainwaves.
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The billions of brainwaves we send produce an enovrmous amount of electrical activity
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in the brain, and this activity can be detected using senisitive medical equipment such as
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39 an Electroencephalograph (EEG), to measure the different electricity levels over areas of
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40 the scalp. Each brainwave has its own characteristic, and they can be characterised into
41 five groups known as Delta, Theta, Alpha, Beta and Gamma frequency bands [2-4].
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Table 1 shows the detail of the of the brainwave band and its relation to the amplitude
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and frequency [5]
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48 Brainwaves Freq (Hz) Amplitude (µV)
49 Gamma 35-100 Lowest
50 Beta 13-35 Very low
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Alpha 8-12 Medium
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Theta 4-7 High
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Delta 0.1-3 Highest
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Table 1 – brainwave frequency band with relation to frequency & amplitude
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The examination of the cognitive process during rifle and pistol shooting as well as
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58 Archery has used EEG to measure the brain activity during the process of target
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Measurement and Control Page 2 of 11
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3 shooting [6-7]. This has given rise to consistent findings that the brain activity differs
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between professionals and novices with experts having a greater EEG alpha power
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during the final few seconds prior to the shot release.
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EEG Alpha reflects the visual attention where an increase in the Alpha power gives a
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9 reduction in the visual attention [8]. With pistol shooters, the increase in the alpha
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power is due to the subjects’ maintaining an optimal sight picture during the aiming and
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the trigger pull, and the alpha power providing an index of the amount of aim related
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13 information processed within the execution of the shot [6]. Alpha wave involvement is
14 noted to decrease when anticipatory attention tasks are performed, such as recognising
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a visual target [9]. In addition to the decrease in alpha during attention phases, the beta
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17 waves increase during active concentration [10].
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19 This preliminaryF study aims to record the brainwaves of two experienced archers (all
20 with 10+ years of experience) whist shooting arrows and analyse them for repeatability
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patterns and dominant individual EEG activity characteristics during the process of the
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23 shot. Images of the archer are also captured throughout the process for correlating the
24 EEG data across reference points of the shot cycle.
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26 2. Method
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Two subjects were used for the studey both with 10+ years of archery experience and
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30 both having attained scores above the “rMaster Bowmen” standard as prescribed by
31 Archery GB. A series of 12 shots were reco rded with the target placed at a distance of 90
32 meters for the test. Prior to the test, the subjects were allowed to practice at the target
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wearing the EEG device to become accustomed with the device whist shooting.
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35 Placement of the device whist the archer is shooeting is shown in figure 1. Both subjects
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familiarisation, they were not aware of any influence thiat the device was having on their
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39 archery performance.
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Page 3 of 11 Measurement and Control
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3 Figure 1 - Subject wearing the EEG device whilst at the aiming phase of the shot
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5 The phases of shooting an arrow are as follows:
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7 1. Setup
8 2. Draw
9 3. Aim
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11 4. Release
12 5. Follow through
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14 Data was collected from the archers using the EEG device during the different phases of
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the shot along with corresponding images of the archer at a frequency of 30Hz. Data
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17 was captured wirelessly to a laptop in real time and stored for processing. A block
18 diagram of the system is shown in figure 2.
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23 EEG Wireless connection
24 Device Laptop
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31 Figure 2 - Block diagram of the capture system
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Measurement and Control Page 4 of 11
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3 Figure 3 shows a brainwave activity map where the magnitude of a particular
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brainwave band is indicated by the radius from the origin and the frequency of the
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brainwave is related to the angle around the map. This provides a simple visual
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7 indicator of the brain activity at any time.
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9 Data sets were divided into individual shots for each archer. The data collected from the
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EEG device was then traced with the captured images for brainwave exploration at
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landmark points within the shot. Data samples were then analysed for repeatability,
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13 and dominant brainwave characteristics of each archer compared at the landmark
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16 3. Results
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The results of thFe preliminary tests are shown in the line graphs below plotting the
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20 percentage levels of attention against samples being taken at 1/10th of a second (10Hz)
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21 from the EEG device. The data in figures 4 to 7 shows the basic proprietary signals of
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‘Attention’ and ‘Relaxation’ provided by the Neurosky headset. The data in figures 8 to
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13 show graphs of individual brainwave bands – Alpha, Beta and Delta.
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Subject A Shot 1
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70 Attention
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Figure 4 - Attention and relaxation levels of subject A, shot 1
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Page 5 of 11 Measurement and Control
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Subject A Shot 2
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Level
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Figure 5 - Attention and relaxation levels of subject A, shot 2
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23 The sample results presen ted in figures 4 and 5 show the attention and relaxation levels
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of subject A for 2 archery shots; archer A considered that shot represented by the data
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26 in figure 4 was good and shot that produced the data for figure 5 was not so good. The
27 data is presented from the draweing phase of the shot, into the aiming and the release of
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the arrow. The results show a similaer pattern and levels for both shots for subject A
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30 with regards to the attention and relaxartion plots. During the shot process the attention

31 level raises and peaks at 100% from the full draw - samples 65 to 109 for figure 4 and
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sample 46– 72 for figure 5 until the release of the string. The relaxation levels of subject
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A decrease slightly during the shot but remain within the 35% to 65% levels for both
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35 shots. The other 8 data samples for this archer aere remarkably similar, with high
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repeatability characteristics.
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39 Subject B Shot 1
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Attention
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Sample Number
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57 Figure 6 - Attention and relaxation levels for subject B, shot 1
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Measurement and Control Page 6 of 11
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Subject B Shot 2
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Attention
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Figure 7 -Attention and relaxation levels for subject B, shot 2
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23 Figures 6 and 7 show the r esults for subject B over 2 shots; these two shots were chosen
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as examples as Archer B’s shot for the data in figure 6 was less than perfect and the shot
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26 made represented by the data in figure 7 was perfect. Whilst the patterns for subject B
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repeatability during the shot. The leevels for attention increase during the aiming phase
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30 of the shot – samples 45 to 106 for figurre 5 and 49 to 93 for figure 7.

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33 and shot 4 for subject A. In addition to the aRlpha levels measured during the shots, the
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green trace of the plots shows the distinct phases within the shot starting with the
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36 setup; for figure 8, sample 1 to 13, draw, sample 12 to 64, aim, samples 61 to 109,
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126. The markers are plotted on further graphs to illustrate the brain activity for the
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distinct phases of the shot cycle.
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Subject A Alpha levels for shot 1
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Figure 8 - Alpha levels for subject A, shot 1
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The graphs show a distinct pattern for both of the shots with the Alpha 1 levels
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Measurement and Control Page 8 of 11
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Subject A Beta levels for shot 1
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Figure 10 - Beta Levels for subject A, shot 1
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Figure 11 - Beta levels for subject A, shot 4
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As with the alpha levels for the selected shots the beta plots are similar showing lower
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activity during the pre-release shot phases and increasing after the arrow has been
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