Listed As Probable

Performance shapes perception

From the posts on optical illusions in sports file, a really interesting Purdue University study shows that recent performance can cause our eyes and brains to play tricks with how we perceive the world around us:

The researchers used a small, adjustable replica of a (american football) goal post to test players’ perception before and after attempting 10 (field goal) kicks. While standing in front of the real-life goal, participants were asked to adjust the width and height of the model to scale.

The players’ pre-performance estimations didn’t correlate at all with their subsequent success rate. But after 10 field goal attempts, their perceived goal size was highly correlated with peformance.

Interestingly, the change in players’ perception didn’t just depend on how many goals they missed — it also mattered how they missed their goals. Folks who failed because they didn’t kick high enough perceived the crossbar to be taller, while those who kicked to the side viewed it as more narrow.

This must be how receivers appear to Jamarcus Russell this season

"Stand behind that tree 60 ft away and I'll womp you to death with an optical illusion"

It was confirmed nearly half a decade ago that, just as Dizzy Dean claimed in the obligatory title quote above, the curveball is not an optical illusion. In fact changes in horizontal direction of up to 17.5" were measured during the ball's 60' 6" trip to home plate.

In a story similar to last month's post on the visual challenges soccer linesmen make when trying to make the offsides call, a Bucknell professor claims that while yes, the ball can curve, it does so in a very smooth and even manner. He claims the reason a curveball is difficult to hit is that an optical illusion causes the ball to appear to change directions suddenly:

Shapiro said the brain processes objects it sees in peripheral vision differently than things it observes looking straight on. So a batter tracking a pitch from the corners of his eyes might throw himself a curve.

The good professor developed a computerized illustration of his point that won the title of world's best visual illusion (see the illusion and a few of the runners up at the link) which in addition to scoring him a sweet eye-tricking trophy

 

is sure to get him much attention from the ladies.

The old Frank 'Banana' Tanana lollipop-like curve used to look soooo gentle on television I figured that the camera must compress depth and create the illusion of a gently sweeping trajectory...turns out the hitters' own eyes may be playing the trick.

Speaking of optical illusions check out this delivery

Journal Watch looks at soccer officials and faulty body parts

The March issue of Clinical Journal of Sports Medicine has one of the first studies looking at injuries in soccer referees. I know, many of you are probably saying who cares about refs but we in sports medicine are bound by the Geneva Convention to care for all of God's creatures. The results are summarized below:

A total of 41 injuries during the career were reported by 31 of 71 referees (44%). Injuries were incurred more frequently in training than during matches, and all injuries reported resulted in at least 2 weeks of absence from sport. About a quarter of the referees reported an injury, and almost 90% of the referees reported musculoskeletal complaints caused by refereeing during the preceding 12 months. In male referees, hamstring strains and ankle sprains were the most common injuries, and the hamstrings, knee, Achilles tendon, and calf were the most prevalent locations of musculoskeletal complaints. No significant difference in the incidence of injury or in the frequency of complaints was observed between match and assistant referees.

A lot of weaknesses to this retrospective survey study looking at a small sample of officials from the Swiss professional league but it's a good place to start.

No doubt many a reader is thinking that there should have been an eye exam component to the study.

Well, science has attempted to look at this issue as well and the results may make you just a bit more sympathetic. A 1998 Spanish paper claimed that human eye movement was not fast enough to keep up with the task of making the offside call in soccer. So shouldn't having the linesmen simply listen for the sound of ball being kicked while visually focusing on the relationship between attacker and last defender solve this problem?

A 2000 Dutch study that had linesmen outfitted with eye-monitoring goggles and head-mounted cameras disagreed, concluding that "assistant referees get nearly 10% of offside decisions wrong because they are not standing in the right place". Presumably to try and get clear look at the involved parties "assistant referees tend to stand about a metre nearer the goal than the last defender, and this is why they make these mistakes."

(So kids, make your runs on the linesman-side of the last defender) Some sort of robot on a track on the opposite sideline that mirrored the movement of the linesman would provide a visual reference to ensure that the imaginary offsides line is indeed perpendicular. A less ridiculous measure to provide a frame of reference would be to place a few dots in a grid pattern on the vast unmarked territory between the center line and the penalty areas. Hockey's fixed blue line may explain why NHL linesmen seem to be more accurate than their soccer counterparts despite the faster nature of their game.

A final theory for why assistant referrees have trouble with the offsides call (besides those most commonly heard in the stands i.e. they are being paid off, lack a brain, or just "suck") is the flash-lag effect, which posits that our brains try to make up for the limited ability of the eye to track a fast moving object by 'predicting' it to be ahead of its actual position. This may explain why linesmen usually raise their flags whenever the call is close. Would a simple change in emphasis, such as baseball's axiom that 'the tie goes to the runner', help compensate for this compensation? 

Backyard Russian Roulette

(Seriously, a "missile game"? Were there no lawyers back then?)

Did you know that a kinder, gentler version of "Jarts" is in stores? Back in my day there wasn't any thrill unless our lawn darts were armed with hollow point armor piercing tips. I think extra points were awarded for performing a bone marrow biopsy on your opponent. Good to know there is still a place for fans of 'horseshoes with a death wish' to find equipment (not legal to sell assembled of course). The new Jarts look like they could still cause a good old blowout fracture so some of the edginess is still there.

Speaking of other dangerous backyard sports, think twice before taking a turn on your kids slip-n-slide. Here is an excerpt from a report by the US Consumer Product Safety Commission:

"Use by adults and teens has the potential to result in neck injury and paralysis. Because of their weight and height, adults and teenagers who dive onto the water slide may hit and abruptly stop in such a way that could cause permanent spinal cord injury, resulting in quadriplegia or paraplegia. The slider's forward momentum drives the body into the neck and compresses the spinal cord. Kransco reports that seven adults and a 13-year-old teenager suffered neck injuries or paralysis while using WHAM-O slides" 

The annual slip-n-slide fraternity party has sent a couple of shoulder dislocations among other injuries to my sports medicine clinic on campus. Mixing alcohol with downhill high velocity body surfing (without the surf) is always a recipe for fun.

All-Terrain Vehicles have quite an impressive track record of good times too.

And then there is the granddaddy of them all, trampolines. The American Academy of Pediatrics says that trampolines are unsafe at any age even though they only cause an average of 88,000 injuries per year in the US, at least 6600 and counting cervical spine injuries, and 14 deaths.

Looks like I'll have to find alternative ways for my kids to play this summer. How about a souped up pogo stick? What could possibly go wrong?

Dwight Howard's Eye Injury

Back in 1983 at the Isiah Thomas summer basketball camp, outfitted in wrist bands and knee pads but still a year or two before sporting the glasses-croakies combination that became my on court trademark (away from the court I pulled off the rare head gear - neck gear double dip that the 6th grade ladies loved) I was elevating for mid-range jumper when an outclassed, earth-bound defender had to resort to sticking his finger directly into my left eye. A trip to the eye doctor later that afternoon left me with a diagnosis of a corneal abrasion and an exotic new eye patch to add to my already formidable list of accessories.

After last night, Dwight Howard and I now have something, OK one lone thing, in common when it comes to basketball. Howard was swiped across the eyes by Samuel Dalembert and reported "seeing just a whole bunch of crazy stuff" and that his eyeballs felt like they were pulsating. The Magic center vowed he would be ready for Game 2 and if the diagnosis is corneal abrasion(s) then that is certainly likely.

The cornea is made up of a thin layer of skin-like cells that cover the pupil and iris of the eye. The classic symptom of a corneal abrasion are eye irritation with a feeling like something is in the eye that you just can't get out. Eye watering, sensitivity to light, and vision trouble can also occur.

Here are some of thoughts we team docs have when managing this injury:
1. The pirate look is out.
Sad but true. Patches have not been shown to help corneal abrasions heal any faster, which makes sense if you think about it. A patch holds your eyelid down over the injured eye which continues to move as you look around with the other eye possibly causing continued mild trauma to the cornea. Less oxygen may get to a patched cornea and so slow healing as well. The only way patching may help is if sensitivity to light is really a problem.

2. No drops, maybe ointment.
We try not to get in the habit of using anesthetic drops just to get someone back to play because they can slow healing and may blunt the ability of the eye to protect itself by blinking. As for antibiotics, infection is an uncommon complication of corneal abrasions but easy enough to prevent with preventive antibiotics, especially if the poking agent is a dirty object like a tree branch. We use antibiotic ointments because the lubricating effect lessens eye discomfort

3. When to return to activity.
We tend to hold people out of work or athletics if their vision is affected. Many negotiate with me by saying they can see fine by just keeping one eye closed. Sounds good in theory until the loss of depth perception that occurs with monocular vision causes big trouble when the linebacker in your rear-view mirror is a lot closer than he appears or your free throws come up a foot short. If vision is good and discomfort is manageable we let them back into the action, sometimes with protection such as a visor for a football helmet.

Fortunately almost all corneal abrasions resolve within 1-3 days. It is still important to see a physician, and usually a family doctor is very comfortable handling this type of case, to be sure the abrasion isn't large or complicated and that other injuries of the eye are not present.

Unfortunately I my jumpshot makes it look like I'm still wearing that patch on my eye. Aaargh .