Olympic Countdown - Hockey

Penalty corners - Quite a lot of research has been done on the visual strategies of goalkeepers in football when trying to save a penalty. Very little such research has been done in field hockey (as opposed to ice hockey). If the defensive team commits a foul inside the shooting circle, the attacking side are awarded a penalty corner. All the defending players but five (including the goalkeeper) must stay behind the back line, while the other six have to stay behind the centre line. One attacker pushes the ball towards his team mates just outside the circle. One of them stops the ball and another one tries to score. If the ball is hit, it has to stay quite low to the ground, making it easier for the keeper to spread himself to save it. However, a flick is allowed to go higher, leading to the development of the “drag flick”. The drag-flicker gets the ball on the shaft of the stick and slings it towards the goal. One of the best known exponents of this art was England’s Calum Giles. So the goalkeeper has two possible strategies. One would be to focus initially on the pusher, and to follow the ball all the time. The other would be to keep their focus on the stopper and the drag-flicker at the edge of the circle. About a third of all goals are scored on penalty corners, so it would be really useful to know what the best strategy is. Canal-Bruland et al (2010) presented skilled hockey goalkeepers with video-clips that were captured either with a moving camera that followed the ball, or with a stationary camera that was directed towards the stopper and drag-flicker. The video clips were occluded 80ms after ball release from the flicker’s stick. Participants indicated where they thought the ball would go by pushing a joy-stick to one of the four corners as if they had to block the ball. They found that when they were presented with a moving picture that started with the pusher and ended with the drag-flicker, the goalkeepers were more likely to overshoot their gaze, beyond where the ball was stopped by the stopper. This tended to be associated with poorer decision making. Goalkeepers who spent more time fixating the ball and stick area, rather than following the ball, tended to make more successful decisions, whether the camera was fixed or moving. Also, goalkeepers who waited longer before initiating a movement tended to be more successful. What’s still not known is what information precisely the best goalkeepers are using. Is it something to do with the angle of the stick or simply the early movement of the ball? Research from football suggests that the direction may be picked up early on, but you need to be able to see the early path of the ball in order to judge the height. With advances in digital photography, it should be possible to highlight the relevant areas so you can work out the early cues that are being given. Then, all (!) you have to do is train your goalkeeper to recognise the cues, and your drag-flicker to disguise them. David Donner

Meeting A World Cup Legend

I was fortunate enough to meet George Cohen recently – what a lovely bloke! He was mostly talking about his 1966 experiences and his successful battles with cancer. He did, however, remark that too many full backs are ball watching when they should be watching the player they’re marking. This means that they can often be seen running backwards half-turned, making it easy for their opponent to get past them. He said he’s seen coaches getting players to run along narrow lines and getting them to turn on the shout of “Turn”. No wonder the great man was horrified. Surely, even the most junior of coaches must realise that this is completely useless unless wingers are made to shout “Turn” every time they attack. It beggars belief that professional footballers are being coached in this way. It’s on a par with teaching people to dribble by setting out a slalom of cones. It’s already been 46 years since England won the World Cup. Until the principles of sports vision become more widely understood and practiced, it could be at least another 46 years before we win it again. David Donner

Olympic Countdown - Handball

The subject of discrimination against women in sport is a topical one, with a recent documentary by Gabby Logan for the BBC, and the controversy about the refusal of Augusta National to allow women members. If you’re refereeing a sporting event, a foul is a foul, and in theory it shouldn’t matter whether it’s made by a male or female athlete. However, it’s difficult to escape from seeing others as stereotypes. Research has shown that people explicitly expect and prefer that women show traits such as kindness and gentleness, and that men show confidence and aggressiveness (Eagly 2007; Deaux & Lafrance 1998). So it’s common for individuals of either gender to be more shocked by aggressive behaviour from women than from men (Deaux & Lafrance 1998; Knight, Guthrie, Page & Fabes, 2002). Indeed, female interactions are perceived as more than male interactions, even when both situations are similar (Condry & Ross, 1995). With regard to handball, Souchon et al (2004) found that male referees more frequently gave the ball back to the victim of aggressive behaviours in females than in male games, and that referees gave disciplinary punishments more frequently when fouls were made by women than by men. So it seems that referees do apply the rules of the sport differently according the gender of the players. There’s evidence that this bias can persist even at high levels of the sport. Kolnes (1995) found that some women playing for the top international Norwegian handball team thought that they are refereed very severely and unfairly when they behave too aggressively or are perceived as acting in a masculine manner. According to these women, severe punishments could be avoided by adopting a seductive and feminine (non-argumentative) attitude towards the referees, who are usually men. It’s possible that referees play advantage more often than men, if men are more skilful at being able to continue their play despite being fouled. However, this effect would be less likely to occur at the highest levels when women are more skilled. To investigate this further, Souchon et al (2009) filmed 30 matches (15 men’s and 15 women’s) from the First Division of the French Handball Championships. All the referees were men. In handball, there are two types of award that the referee can give when there’s a foul: award a 9-metre throw (give the ball back to the victim where the foul occurred); or award a 7-metre throw (a direct shot on goal like a football penalty). There are also three possible disciplinary sanctions: a yellow card warning; a 2-minute suspension from the game; or a red card, meaning permanent exclusion from the game. For the 9-metre throws, referees were more likely to punish female players than male players, but there was no difference for the 7-metre throws. So referees were more likely to mete out mild punishment (as opposed to no punishment) to female players, while giving severe punishments to the same extent to both sexes. There was no difference between the sexes when it came to disciplinary decisions. The lack of difference for severe offences and discipline may be because these decisions are much rarer in games. For instance, there were relatively few yellow cards or 2-minute suspensions, and no red cards in any of the 30 matches. Players averaged more than 150 transgressions in each match. Souchon gives “benign” and “hostile” sexism as possible explanations for the referees’ behaviour. They might hold the (subconscious) view that women have less sporting ability than men, so may be less able to withstand being fouled, so would be less likely to play advantage. They may also believe that a woman who falls during a game is not play-acting, whereas a man is more likely to “dive” (benign sexism). On the other hand, if they have a perception that women should not be aggressive, any aggressive behaviour they do show will be magnified, and more likely to be punished (hostile sexism). I've umpired a few ladies’ cricket games, and always enjoyed them. I’ve never had any disciplinary issues, but if they were to occur I’ll try and treat them the same as I would do in a men’s match. I still think I might be a bit shocked, though. David Donner

Olympic Countdown - Gymnastics

I’ve described what Joan Vickers has called the “Quiet Eye”, when experts fix their gaze on a particular place, usually just before making the required movement in their sport (such as a golfer about to putt). One would think this would be rather difficult for a gymnast performing multiple twists and turns, but it seems that expert gymnasts do actually have a similar strategy. Several investigators have found that vision is essential in to a stable landing after performing a somersault (Davlin et al, 2001; Luis & Tremblay, 2008). But until recently, there was little evidence to show exactly how this was achieved. To resolve this, Heinen (2011) got experts and apprentices to carry out a tucked back aerial somersault on a trampoline whilst wearing a helmet fitted with an infra-red camera that tracked their eye movements. One of the striking differences that were found between experts and apprentices was that experts didn’t blink at all during somersaults, whereas apprentices nearly always blinked. This is a strong indication that experts are using visual information to judge their body position more accurately. For eye fixations, the researchers defined a fixation as when the eyes were fixating a specific position for at least 100 milliseconds. They found that for experts, the longer they fixated during take-off, the more accurate were their landings. But this wasn’t true for apprentices. The reason could be related to take-off velocity. Take-off velocity is important because it relates to how long the athlete is in the air. They need enough flight-time to be able to complete the task accurately. It’s already been found that it’s easier to determine your speed through vision than from feedback from your muscles or ears (Lee et al, 1992). This suggests that through experience, experts are able to use visual information at the start of their somersault to adjust the time they take to extend their body, and thus make better landings (in the centre of the trampoline). There’s still plenty of research to be done, for instance finding out exactly what the experts are fixating. But there’s one obvious piece of advice to novice gymnasts. Keep your eyes open. David Donner

Olympic Countdown - Fencing

It can take less than 300 milliseconds for an elite fencer to complete an attack. If you’re going to parry it away successfully, you really need to be able to read the direction of the attack as it’s about to be launched. Afterwards will probably be too late. This, not amazing reaction times, is the key to success in fencing. So the key question is what information do the experts get from studying their opponent that enables them to do this? Several attempts have been made to find out, notably Bard et al (1981) and Hagemann et al (2010). Bard found that fencers looked mostly at the hand guard, but this was true of both experts and novices. But if you’re looking at one place, it doesn’t mean that you can’t get information from other areas as well. So it could be that the experts were fixed on the hand guard, but were also able to use their peripheral vision so that they could pick up subtle differences in angle between upper and lower arms, or even between the lower arm and the wrist. Hagemann’s group used a variety of techniques, such as occluding areas of the body and fixing eye cameras to participants as they watched videos of an expert fencer launching attacks. They found that experts fixated the upper trunk area longer than advanced or novice groups, and their performance in saying where the attack was aimed was most severely affected when this area was occluded. They then tried highlighting this area to see if it helped novices predict the direction of attack any better. However, far from improving performance, it actually made it worse. The problem was that the area of the upper trunk actually included not just the upper part of the chest, but also the arm and the sword itself. Because the arm and sword would often be in front of the chest, it was impossible for the researchers to digitally occlude them without occluding at least part of the chest as well. And because they were highlighting such a large area (with a red patch), they were probably obscuring more than they were highlighting. You probably would have guessed that it would have been some part of the upper body, sword or arm that the experts were using to judge the attacks, rather than, say, the head or feet. What you really need to know is whether it’s just one crucial area or whether it’s the angles between them that are the key. A start would be to get the expert fencer to make attacks holding something really short, but not a sword. Ideally, you’d then attach something to areas of his clothing that only showed up in certain lights. By turning these areas on and off, you should be able to tell which areas are the crucial ones. You could then use something else to for the expert to wear that highlighted those areas to see if it helped with predictions. I’m almost tempted to do some research myself. David Donner

Olympic Countdown - Equestrianism

Researchers at Nottingham Trent University have been studying the eye movements of horse riders. A show-jumper, an event rider, a cross-country rider and a non-competitive rider completed five rounds of a three-jump course wearing a spectacle-mounted device that tells the researchers where the rider is looking, and how long for. As they approached a jump, all the riders changed their point of fixation from the ground to the jump, and then to the ground beyond. The difference, however, was that the more experienced show-jumper focused on the top rail of the jump much sooner than each of the other riders – up to 3.05 seconds before take-off – and holds it there until take-off. It shouldn’t really be a surprise that in order to time your jump accurately, you need to focus on the obstacle, and not on the ground in front of it. In fact, Laurent, Dinh Phung & Ripoll (1989) have already shown that riders use the increasing size of the image of the obstacle that is formed on their retina to adjust the horse’s gait as it approaches the jump. It would be really interesting to know if the horse does this as well. The eyes of horses are much more widely spread than in humans, so they have a wider peripheral vision, but don’t tend to focus on specific objects as closely as we do. They are also less likely to have as good depth perception, so may not be as accurate at judging distances. They can learn when to jump, however, as long as they are allowed to keep their head up so they can focus on the top of the jump, like the rider. There has been a tendency to design jumps that test the rider, without taking into account the vision of the horse, but our knowledge is gradually improving. Stachurska et al (2002), for instance, found that horses exhibited refusals and “run-outs” when approaching walls, and that the second elements of combination fences prove more problematic than the first or third obstacle of combination fences. They also found that fences with a single colour (especially white) caused more problems than fences with contrasting colours. They also have problems when green is paired with yellow or blue in the colour of a fence. It’s very difficult, if not impossible, to attach eye-tracking cameras to a horse, partly because of the position of their eyes. But I suspect that horses can learn to focus on the top of an obstacle in order to time the jump, and can probably pick it up rather quicker than many riders. David Donner

The Calcutta Cup

Ever had the feeling that someone has been watching a different match to you? This was certainly the case when I turned on the radio after watching the England – Scotland match to hear Matt Dawson say how great England were in the second half. Really? They had two try- scoring opportunities, one from a Scottish mistake which they took, and one from a diagonal kick which was well covered. A good defensive effort certainly, but hardly a great performance, I would have thought. Although England was defensively strong as usual, they would still have lost the game if they’d been playing a side that wasn’t as good at butchering chances as the Scots. Fortunately, if you wanted to know what was going wrong, Jonathan Davies showed the answer. He pointed out when Scotland had a 4-on-3 situation, instead of exploiting it, they went through a pre-determined move with a decoy runner. When their deep runner came through, Strettle was able to come off his wing and make the tackle. And it’s not just the backs that need to know how to pass the ball. In the same match, Richie Gray makes a great break, but then passes the ball behind Strokosch. Then Ross Rennie tries to pass too late when there’s a clear overlap, so his pass is caught up with Foden’s tackle. And on one of the rare moments when England had the chance to create something, a simple pass from Robshaw would have put Ashton clear, but instead he fires the ball above his head. All this suggests teams that are not being put under pressure in their training, but are going through a series of worked moves. You can’t do all the players’ thinking for them, and you certainly can’t see for them. They need to be drilled in looking for space and exploiting it, not putting on some kind of demonstration of synchronised rugby. In football, the players at Barcelona are given the responsibility to change their tactics during a match to respond to the opposition’s tactics. Their players start learning this from the age of 11. The next day saw an example of a player who hasn’t yet had all the vision coached out of him. George North makes a powerful run to the outside shoulder of Gordon D’Arcy, and then offloads like Sonny Bill Williams out the back of his hand to take out three Irish defenders. Good anticipation from Davies and a nice running angle means a try that proved to be the difference between the two sides. The message is simple: let your players think for themselves; let them look for themselves; put them in challenging situations often enough, they’ll make the right decisions eventually. If you don’t, you can’t complain when they mess it up. David Donner