A Decision/Action Model for Soccer –                                   Pt 6                              Paying and captur...
What is attention?                  How does it work as a cognitive process?“Everyone knows what attention is. It is the t...
The fuel for the internal process for attention                  comes through channels and frequenciesInternally generate...
The visual channel and it’s constraintsThe visual system is the primary source of “fuel” for the process of attention. It ...
The visual frequencies and their constraints                          What one is looking at and forThe visual targets for...
Auditory and tactile constraints                 Other targets that can gain attentionWhile vision is the dominant sensory...
The relationship of frequencies and thresholds“Attention has been described as a threshold-based process that determines w...
Common events that can reach a threshold and get attention                             [13]  Novelty – something new, exci...
When do you reach a threshold?There are no universal standards for thresholds. Individuals differ and even an individualca...
Using targets to get at attention                               Signal-to-noise ratio“Signal-detection theory provides a g...
Using targets to get at attention                             Signal-to-noise ratioIn SNR there are two types of signals o...
Four paths for dominating attention            When they pay in attention, overcharge them for a bad ideaOverwhelm them, t...
Destruction and creation                   [3]       How target thresholds rise and fade, the necessity to adapt“To compre...
Destruction and creation                    [3]       How target thresholds rise and fade, the necessity to adapt“On the o...
Summary                                                   Patterns of Conflict      In soccer attention is something that’...
Summary                                             Patterns of Conflict     Recipe for generating confusion and disorder ...
Selected references1.    ARTMAN, H. GARBIS, C. 1998, Situation Awareness as Distributed Cognition (Proceedings of ECCE’98,...
Selected references18.   KLEIN, S. Unknown date, The duality of psycho-physics (School of Optometry, University of Califor...
Thank you              “I’ll live or die by my own ideas.” Johan CruyffPresentation created December 2012 by Larry Paul, P...
Upcoming SlideShare
Loading in …5
×

Paying and capturing attention - A decision/action model for soccer - pt.6

1,104 views

Published on

Viewing attention as both an internally driven process and as an externally driven force.

Published in: Education
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
1,104
On SlideShare
0
From Embeds
0
Number of Embeds
26
Actions
Shares
0
Downloads
69
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Paying and capturing attention - A decision/action model for soccer - pt.6

  1. 1. A Decision/Action Model for Soccer – Pt 6 Paying and capturing attention Viewing attention as both an internally driven process and an externally driven force“Observation is the task that detects events within an individual’s, or groups, environment. It isthe method by which people identify change, or lack of change, in the world around them.While it is not the sole basis for Action, it is a primary source of new information in thebehavioral process.”Frans P.B. Osinga“The often-used phrase “pay attention” is apt: you dispose of a limited budget of attention thatyou can allocate to activities, and if you try to go beyond your budget, you will fail. It is themark of effortful activities that they interfere with each other… You can do several things atonce, but only if are easy and undemanding.”Daniel Kahneman 1
  2. 2. What is attention? How does it work as a cognitive process?“Everyone knows what attention is. It is the taking possession by the mind, in a clear andvivid form, of one out of what seem simultaneously possible objects or trains of thought.Focalization, concentration of consciousness are of its essence. It applies withdrawal fromsome things in order to deal with others, and is a condition which has a real opposite in theconfused, dazed, scatter brained state which the French call distraction, and Zerstreutheit inGerman.” [27]“Bottom-up processing proceeds in a “single direction from sensory input, through perceptualanalysis, towards motor output, without involving feedback information flowing backwardsfrom ‘higher’ centers to ‘lower’ centers.” [27]  Bottom-up processing is expressed by System 1; the Dorsal Stream between Sensory Memory and Sensory-Motor Memory in the LIDA Model and the Implicit Guidance and Control path between Orientation and Action in the OODA Loop. Bottom-up processing uses fast-and-frugal heuristics and operates on lower and quicker time-scales. It is a ‘management process’ using the smallest amount of computational time and power.“During top-down processing, “the flow of information is from ‘higher’ to ‘lower’ centers,conveying knowledge derived from previous experience rather than sensory stimulation.” [27]  Top-down processing is expressed by System 2; the Ventral Stream that leads to consciousness and the Global Workspace in the LIDA Model and the Decision (Hypothesis) path that leads from Orientation to Action in the OODA Loop. Top-down applies slower rational decision-making and higher time-scales. It is a ‘leadership process’ requiring a higher cost in computational time and power, therefore a greater amount of attention must be paid. 2
  3. 3. The fuel for the internal process for attention comes through channels and frequenciesInternally generated attention is fed primarily through three interrelated sensory systems(channels); sight, hearing and feeling (not emotions).Each channel carriers numerous bits of data and information from a variety of sources(frequencies), in different forms and in different time-scales. At any time a player can; seean almost infinite number of targets for their attention; hear many different sources forsound; feel a variety of different sensations. Each of the three major channels has differentfrequencies competing for immediate attention.The competition for attention is decided though a player/s distributed genetic heritage,cultural traditions and previous experience, new experiences and feedback from theenvironment. Attention is distributed because players should not be alone, collaboration,watching each others back, is the preferred option.A decision needs to be made, (hold or change) when a key frequency* reaches a certainthreshold. [15,29]*With three competing channels, each with multiple frequencies, each frequency withdifferent thresholds, attention must be given to which ‘key frequencies’ threshold emergesfirst. Selection of which ‘one is the key’ is a central problem in decision-making. Thequestion, “do I wait for what’s planned to materialize or do I go with the first optionavailable and move on from that plan?” is at the heart of the heuristics vs. rationalapproach argument. Each frequency carries it’s own cost/benefit in the larger picture.[15,19,25,29] 3
  4. 4. The visual channel and it’s constraintsThe visual system is the primary source of “fuel” for the process of attention. It has thehighest computational cost and uses the ‘greatest amount of attentions bandwidth.’ For acloser look at how the visual system in soccer works see the following videos: [27,28]“A decision-making model for sport; Boyd’s OODA loop applied to soccer;”  Part 2 – Observations in soccer, the data, information, knowledge, wisdom model: http://www.youtube.com/watch?v=UywPrsWawL4&list=UUI6vwbM9FKPl8JCJBWsOYbA&index=22&f eature=plcp 2:28  Part 3 – Attention and gaze control in soccer, a look at six types of attention: http://www.youtube.com/watch?v=Bt7zwJsDSwg&list=UUI6vwbM9FKPl8JCJBWsOYbA&index=21&fe ature=plcp 3:33  Part 4 – Visual targets for attention, preattentive filters, concrete and abstract targets for attention: http://www.youtube.com/watch?v=U4BU6lpl3DY&list=UUI6vwbM9FKPl8JCJBWsOYbA&index=20&fea ture=plcp 4:12  Part 5 – Visual workspaces, where the are targets hiding: http://www.youtube.com/watch?v=VC877i_qqDY&list=UUI6vwbM9FKPl8JCJBWsOYbA&index=19&fe ature=plcp 4:05  Part 6 – Visual limitations, sensation and perception, hardware and software work together: http://www.youtube.com/watch?v=ussu4WZ0Hx0&list=UUI6vwbM9FKPl8JCJBWsOYbA&index=18&fe ature=plcp 4:14  Part 7 – Complex emergent systems, “parts spontaneously adjusting and adapting to each other:” http://www.youtube.com/watch?v=Y5a6KW3f4YU&list=UUI6vwbM9FKPl8JCJBWsOYbA&index=17&fe ature=plcp 3:21 4
  5. 5. The visual frequencies and their constraints What one is looking at and forThe visual targets for attention are the same thing as the visual frequencies. What one seescomes in two categories.  Concrete:  Objects; entities that are free to move about the field, primarily people and the ball.  Locations; things that do not move and serve as reference points, i.e. the goals, the fields markings, near & far post.The movement of objects against a background of concrete locations creates the need forabstract concepts. Dynamic, transient and complex “ideas” that one attempts to match toan evolving world.  Abstract:  Locations; nonphysical, transient spaces, (they have names) which change as objects move within the field and game flow, i.e. blindside, goal side, between, around, over, an offside position, overlap, passing angle.  Systems; the actual or potential paths of interactions between concrete objects and locations, i.e. a schematic. Systems can be tightly or weakly coupled, may include members of both teams, networks and hubs.  Probabilities; the perceived value of the observed systems. Given a player/s limited time, information and computational power what is the potential that ‘this’ target can be exploited or poses a threat? (See heuristics). At the probability level, systems take on value and meaning in the search, stop, decision rules. 5
  6. 6. Auditory and tactile constraints Other targets that can gain attentionWhile vision is the dominant sensory channel, hearing and touch can override it and shareattention for short periods. This requires distributed attention, a switch task. [7,16]Sound is primarily generated by objects for short periods in a serial fashion, a call, thesound of the ball being struck. Auditory frequencies have two main elements; volume, is itloud enough to be heard and familiarity, do we understand it. For the later, one may needto attend to an entire message. When the message length exceeds the psychologicalpresent System 2 must focus on it, i.e. a coaches lecture. [14,17] That drains attention fromother tasks and points to the need for heuristics to save time and energy. Each frequency isa ‘sound generation’ by a different object, i.e. all of the transmitters within ones auditoryfield can potentially be heard.Touch is the sensory channel that warns us that something is very close and may requireimmediate attention and action. Touch, or feeling, may develop slowly like the sense offatigue or quickly like a pulled muscle. Even the anticipation of physical contact candominate attention and alter behavior, see danger in Clausewitzian Friction in Part 1.Individuals are not alone in anchoring, framing, directing and holding attention. In thedistributed situational awareness model attention is a group concern. The group shares, forgood or ill, a collective genetic heritage, cultural base, previous experience and multiplephysical perspectives. That sharing of information must contend with, and take advantageof different timescales within the group. [1,2] That requires a high level offingerspitzengefühl. 6
  7. 7. The relationship of frequencies and thresholds“Attention has been described as a threshold-based process that determines whether or notwe become aware of a stimulus… Some researchers have attributed additional roles toattention: as a filter on what is perceived, and as a stabilizing force on sensorymechanisms.” [10]Frequencies are numerous, come from different channels and present an evolving picture of“state changes” in the environments. They require different cognitive functions to integratethe incoming flow into harmonious action between team members. That action will becoordinated through explicit and implicit visual, verbal and tactile communication. The goal;to match the groups evolving cognitive picture to the evolving external realities.Furthermore, the group usually includes an opponent/s who actively resist and attempt todisrupt or reorient the groups targets of attention.Thresholds serve two functions for frequency control; they serve notice about changes andsignificant events. [17] In the first case, signals cannot be sustained indefinitely, they decaywithout fresh input and their relevance changes. Significant events include dramaticchanges and surprise events. They are either a matter of expectations being dramaticallymissed or a ‘total surprise’ like a blind side run. Survival is dependent on choosing whichfrequency carries the most important signal and monitoring its threshold. Is it what you see,hear or feel? Does one attend to gradual change or some unforeseen development that justpops up? 7
  8. 8. Common events that can reach a threshold and get attention [13] Novelty – something new, exciting, unexpected. Relevancy – something that pertains to the current search. “That’s it!” Informativeness – something that serves as a clue and helps guide the next decision/action. Problems – either yours or theirs. Something lets you know that a change, wanted or not, maybe about to happen. Often the ‘gut feeling.’ Inconsistency – erodes trust between players. Sensemaking begins to crumble and a problem might be next. Violated expectations – the moral code between players is broken. Sure attention getter. Whatever can’t be dealt with by unconscious, automatic processors – this is the point when System 2 must get involved, attention must be paid. Both teams experience and can create these events. Attention to the opponent and what external events effects their cognitive picture is as important as what is happening within ones own team. Creating these situations is a path to dominating the opponents while maintaining cohesion. 8
  9. 9. When do you reach a threshold?There are no universal standards for thresholds. Individuals differ and even an individualcan experience different thresholds in similar situations. Experience and training cansharpen the skill of detection while fatigue, aging and the opponents can dull or mislead it.That said, a key to improving speed of play is to increase threshold sensitivity withouthitting paralysis by analysis.An example of a visual threshold sensitivity. Carefully look at the black square below. Isthere any difference in the color value? If so what is the difference and where is it?*Questions in soccer are more complicated then this. In soccer, onedoesn’t get too many opportunities to calmly study an object. Objectsdon’t sit still, frozen in time and some have the capability tointentionally mislead. Yet one employs the same visual hardwareand software in this example as well as under match conditions.The answer to these questions shows that there are genetic, cultural, temporal andexperiential limits to what one can visually perceive.*The square isn’t uniform. It’s divided in half from the top right corner to the bottom left. The upper left triangle has a CMYKvalue of 83, 72, 70, 90; the lower right 84, 73, 71, 90. The visual system is not sensitive enough to appreciate a difference, it isbelow the level of discrimination. Examples can be made for sensitivity thresholds in the other two channels. 9
  10. 10. Using targets to get at attention Signal-to-noise ratio“Signal-detection theory provides a general framework to describe and study decisions that aremade in uncertain or ambiguous situations. It is most widely applied in psychophysics – thedomain of study that investigates the relation between physical stimulus and its subjective orpsychological effect – but the theory has implications about how any type of decision underuncertainty is made.” [29]“The starting point for signal detection theory is that nearly all decision making takes place in thepresence of some uncertainty. Signal detection theory provides a precise language and graphicnotation for analyzing decision making in the presence of uncertainty… There are two kinds ofnoise factors that limit the subject’s performance: internal noise and external noise.” [15]“Signal-to-noise ratio is a measure used in science and engineering that compares the level of adesired signal [the key target for attention] to the level of background noise [everything else]…SNR is sometimes used informally to refer to the ratio of useful information to false or irrelevantdata in a conversation or exchange.” WikipediA “Improving SNR in practice. All real measurements are disturbed by noise. This can includeexternal [and internal] events that affect the measured phenomenon [what one observes andexperiences] — weather, opponents, coaches, fans, being preoccupied etc., depending on what ismeasured [the game situation/schwerpunkt] and of the sensitivity of the player/s. It is oftenpossible to reduce [or increase] the noise by controlling the environment.” Modified WikipediA 10
  11. 11. Using targets to get at attention Signal-to-noise ratioIn SNR there are two types of signals open for consideration, noise or signal, and twopossible options, attend or ignore. This means there are four possible outcomes as thediagram below shows. [29]“Two of these possibilities, hits and correct rejections, are correct; the other two, falsealarms and misses are errors.” [29]The player/s that have a higher ratio of hits and correct rejections compared to theopponents will have a decided advantage. They will see more clearly through the Fog ofWar and spend less time considering dead ends and red herrings. [15,29] 11
  12. 12. Four paths for dominating attention When they pay in attention, overcharge them for a bad ideaOverwhelm them, task saturation. Create so many options for the opponent that they havea “helmet fire” and noise overwhelms the environments. The problem with this path is thatit takes a lot of mass and energy in motion. That makes it difficult over long periods. Sincethe environment/s may become unpredictable ones own team cohesion can begin tounravel. (Predictability is one of the foundations of trust.)Sell certainty, then deceive them. “Convince the enemy we are going to do something otherthan what we are really going to do in order to induce him to act in a manner prejudicial tohis own interests. The intent is to give the enemy a clear picture of the situation, but thewrong picture.” [22]Confuse them, create ambiguity. “Act in such a way that the enemy does not know what toexpect. Because he does not know what to expect, he must prepare for numerouspossibilities and cannot prepare adequately for any one.” [22]Sneak up on them, surprise creates a significant event. “Deny the enemy any knowledge ofimpending action. The enemy is not deceived or confused as to our intentions but iscompletely ignorant of them.” [22]When these four paths are used harmoniously a team will have “The ability to operate at afaster tempo or rhythm than an adversary [which] enables one to fold adversary back insidehimself so that he can neither appreciate nor keep-up with what’s going on. He will becomedisoriented or confused;” [4] 12
  13. 13. Destruction and creation [3] How target thresholds rise and fade, the necessity to adapt“To comprehend and cope with our environment we develop mental patterns or concepts ofmeaning… In a real world of limited resources and skills, individuals and groups form,dissolve and reform their cooperative or competitive postures in a continuous struggle toremove or overcome physical and social environmental obstacles… Against such abackground, actions and decisions become critically important. Actions must be taken overand over again and in many different ways. Decisions must be rendered to monitor anddetermine the precise nature of the actions needed that will be compatible with the goal.” [3]  In soccer, survival requires a collaborative effort to endure constant stress and continual evolution. Isolated individuals don’t do well over time. Harmonious inter-subjectivity is the goal.“Naturally, as we go through life we develop concepts of meaning (with includedconstituents) to represent observed reality.” [3]“When this orderly (and pleasant) state is reached the concept becomes a coherent patternof ideas and interactions that can be used to describe some aspect of observed reality. As aconsequence, there is little or no further appeal to alternative ideas and interactions in aneffort to either expand, complete, or modify the concept . Instead, the effort turned inwardtowards fine tuning the ideas and interactions in order to improve generality and produce amore precise match of the conceptual pattern with reality.” [3]  In a match paying attention never rests. As soon as it has found a key threshold, it begins to look deeper into it, running comparison/contrast tests against experience and the evolving reality which eventually result in a mismatch. 13
  14. 14. Destruction and creation [3] How target thresholds rise and fade, the necessity to adapt“On the other hand, we suspect that refined observations now underway will eventuallyexhibit either more or a different kind of precision and subtlety than the previousobservations and thought patterns. Clearly, any anticipated difference, or differences,suggests we should expect a mismatch between the new observations and the anticipatedconcept description of these observations.” [3]  One begins to suspect that there is a better fit or answer. Either a different frequency is moving into the spot light, i.e. approaching its threshold, the one that’s being attended to is fading, or it’s really not at its threshold yet.“To avoid such a discomforting position implies that we should anticipate a mismatchbetween phenomena observation and concept description of that observation. Such a notionis not new and is indicated by the discoveries of Kurt Gödel and Werner Heisenberg.” [3]  The only thing permanent is change. Change occurs internally, concept formation, and externally, the world. Finding a match is finding equilibrium, good luck with that.“According to Gödel’s Incompleteness Theorems, Heisenberg’s Uncertainty Principle, and theSecond Law of Thermodynamics one cannot determine the character or nature of a systemwithin itself. Moreover, attempts to do so lead to confusion and disorder.” [3,4]  Interactions are the key to survival and growth, isolation the path to decay and death. 14
  15. 15. Summary Patterns of Conflict In soccer attention is something that’s always in demand and open to influence. Like a currency, it has value that is influenced by many different factors. One looks to get the highest return on his or her investment while compelling the opponent to spend more then they should on theirs. The battle to protect your attention while demanding the most from the opponents is summed up in John Boyd’s Patterns of Conflict. The transfer from air-to-air combat and tactical thinking to soccer is simple, clear and I won’t alter the original examples in the following.  Action:  Exploit operations and weapons that:  Generate a rapidly changing environment (quick/clear observations, orientation and decisions, fast-tempo, fast transient maneuvers, quick kill)  Inhibit an adversary’s capacity to adapt to such an environment (cloud or distort his observations, orientation, and decisions and impede his actions)  Idea:  Simultaneously compress own time and stretch-out adversary time to generate a favorable mismatch in time/ability to shape and adapt to change  Goal:  Collapse adversary’s system into confusion and disorder causing him to over and under react to activity that appears simultaneously menacing as well as ambiguous,chaotic, or misleading. Slide 7.Defense and the National Interest; www.d-n-i.net January 2007; http://www.ausairpower.net/JRB/patterns_ppt.pdf 15
  16. 16. Summary Patterns of Conflict Recipe for generating confusion and disorder  Observations  Quick/clear scanning sensors  Suppressed/distorted signatures Activity  Fire  Quick shoot fire control systems and high speed weapons  Movement  High speed (supercruise)  Rapid energy gain and rapid energy loss coupled with high turn rates and low turn radii  High pitch rates/high roll rates/ high yaw rates coupled with ease of control Slide 8Defense and the National Interest; www.d-n-i.net January 2007; http://www.ausairpower.net/JRB/patterns_ppt.pdf 16
  17. 17. Selected references1. ARTMAN, H. GARBIS, C. 1998, Situation Awareness as Distributed Cognition (Proceedings of ECCE’98, Limerick).2. ARTMAN, H. 2000, Team Situation Assessment and Information Distribution (Ergonomics, Vol. 43, No. 8, 1111- 1128).3. BOYD, J. 1976, Destruction and Creation (http://pogoarchives.org/m/dni/john_boyd_compendium/destruction_and_creation.pdf)4. BOYD, J. 2006, The Strategic Game of ? and ? (http://www.dnipogo.org/boyd/strategic_game.pdf)5. BURBECK, S. 2007, Complexity and the Evolution of Computing: Biological Principles for Managing Evolving Systems (Muticellular Computing, V2, 2, 1-41).6. CHEN, E. KATILA, R. 2008, Rival Interpretations of Balancing Exploration and Exploitation: Simultaneous or Sequential? (Handbook of technology and innovation management, John Wiley & Sons Ltd. 197-214).7. CRENSHAW, D. 2008, The Myth of Multitasking, How “Doing it all” Gets Nothing Done (San Francisco: Wiley Imprint).8. DAVIDS, K., BUTTON, C. & BENNETT, S. 2008, Dynamics of Skill Acquisition, A Constraints-Led Approach (Champaign, Il: Human Kinetics).9. DITTERICH, J. MAZUREK, M. SHADLEN, M. 2003, Microstimulation of Visual Cortex Affects the Speed of Perceptual Decisions (Nature Neuroscience, Vol. 6, No. 8, 891-898).10. FAGHIGI, U. McCALL, R. FRANKLIN, S. 2012, A Computational Model of Attentional Learning in a Cognitive Agent (Elsevier, Biologically Inspired Cognitive Architectures, Vol. 2, Oct. 2012, 25-36).11. FRAISSE, P. 1984, Perception and Estimation of Time (Annual Reviews Psychology, 1-36).12. FRANKLIN, S. 1997, Artificial Minds (London, England: Bradford Book).13. FRANKLIN, S. February 2005, How Minds Work, Global Workspace Theory (http://ccrg.cs.memphis.edu/tutorial/PDFs/Global%20Workspace%20Theory.pdf).14. HAYES, L. 1992, The Psychological Present (The Behavior Analyst, 1992, 15, 139-145).15. HEEGER, D. 1997, Signal Detection theory (www.cns.nyu.edu/~david/handouts/sdt-advanced.pdf)16. JOHANSSON, F. 2004, The Medici Effect, Breakthrough Insights at the Intersection of Ideas, Concepts & Cultures (Boston, Ma: Harvard Business School Press).17. KAHNEMAN, D. 2011, Thinking Fast and Slow (New York: Farrar, Straus and Giroux). 17
  18. 18. Selected references18. KLEIN, S. Unknown date, The duality of psycho-physics (School of Optometry, University of California. Berkeley, CA 94720, USA. cornea.berkeley.edu/pubs/60.pdf).19. KOCH, C. 2004, Selective Visual Attention and Computational Models, (http://www.klab.caltech.edu/cns186/PS/attentionkoch.pdf).20. LUAN, S. 2011, A Signal-Detection Analysis of Fast and Frugal Trees (Psychological Review, Vol. 118, No. 2 316- 338).21. MARCH, J. 1991, Exploration and Exploitation in Organizational Learning (Organizational Science, Vol. 2 No. 1 Feb. 1991, 71-87).22. MARINE CORPS, U.S. 1997, MCDP 1, Warfighting (http://www.dtic.mil/doctrine/jel/service_pubs/mcdp1.pdf).23. OSINGA, F. 2007, Science, Strategy and War, The Strategic Theory of John Boyd (New York: Routledge).24. RAO, V. 2011, Tempo, Timing, Tactics and Strategy in Narrative-Driven Decision-Making (Ribbonfarm Inc).25. RICHARDS, C. 2004, Certain to Win, The Strategy of John Boyd, Applied to Business (Xlibris Corporation).26. SHAPIRO, L. 1994, What is Psychophysics? (PSA 1994, Vol. 2, 47-57).27. VICKERS, J. 2007, Perception, Cognition, and Decision Training, The Quiet Eye in Action (Champaign, Il: Human Kinetics).28. WILLIAMS, A.M., DAVIDS, K. WILLIAMS, J.G., 1999, Visual Perception & Action in Sport (London, England: Taylor & Francis).29. WICKENS, T. October, 2011, Elementary Signal Detection Theory, (Oxford University Press.) 18
  19. 19. Thank you “I’ll live or die by my own ideas.” Johan CruyffPresentation created December 2012 by Larry Paul, Peoria Arizona.All references are available as stated.All content is the responsibility of the author.For questions or to inquire how to arrange a consultation or workshop on this topic or the others in the series you can contact me at larry4v4@hotmail.com, subject line;decision/action model.For more information visit the bettersoccermorefun channel on YouTube. 19

×