Conventional ergonomics guides suggest aligning the top of the monitor to where the operator looks at straight on. It seems doubtful that that still applies to today's 24" and 30" and larger displays.
What was the reasoning behind that rule? What's the correct way to position a huge display according to current research?
Would anyone have a reference to research confirming the "2/3 up" rule?
Actually, the rule of thumb is to align your eyes (straight ahead) to about 3/4 up the height of viewable area of the screen. That is, about 1/4 of the screen is above eye-level, the rest is below and this should apply to any reasonable screen size.
Beyond that rule of thumb, the bottom of the screen should not be more than 60 degrees below the straight ahead horizontal viewing angle.
I'll discuss the specific recommendations below, but let me start with the basis for them.
The question in this thread was recently re-asked (and marked as a duplicate). The reason was that the information here, and elsewhere, is old ("Has the science changed?"; is the underlying research still current?). Even in this question, the applicability of the research is questioned due to the growing size of monitors ("It seems doubtful that that still applies to today's 24" and 30" and larger displays"). These concerns are understandable given that the OSHA advice cited in one answer shows what looks like 14" CRTs from the early 1980s.
The OSHA recommendations were based on extensive research focused on human physiology. Humans are a few inches taller, on average, than we were centuries ago (thought to be mainly due to diet and medicine), but we have not evolved in the last few decades to adapt to growing monitors. The research behind workspace ergonomics still applies.
You can answer that with basic trigonometry. The OSHA guidelines discuss an optimum where the screen occupies a visual angle of roughly 30 degrees (top of the screen slightly below straight ahead and the center of the screen down 15 to 20 degrees from straight ahead). The rule of thumb for monitor distance is arm's length (about 28-30"). That gives you a total screen height of roughly 16", equivalent to a 32" monitor in a 16:9 format.
The OSHA guidelines discuss an upper limit where the entire screen fits in a 60 degree visual angle (which would require a little head movement to view top to bottom). A screen that size would be viewed from farther away, and the guidelines discuss a maximum distance of 40". That equates to a screen nearly 6 feet high, which would be a 12 foot 16:9 monitor.
If your problem is that your monitor is larger than 12 feet diagonally, you can probably afford regular chiropractic care and good glasses, and you will have the satisfaction of knowing that your monitor makes other people drool.
The top of the monitor should be at or slightly below eye level. The center of the computer monitor should normally be located 15 to 20 degrees below horizontal eye level (Figure 6).
The entire visual area of the display screen should be located so the downward viewing angle is never greater than 60 degrees when you are in any of the four reference postures. In the reclining posture the straight forward line of sight will not be parallel with the floor, which may increase the downward viewing angle. Using very large monitors also may increase the angle.
I personally have followed all of the standard advice, most of it listed above, but what was the ultimate solution was paying attention to if I slouch or not and correcting it.
The algorithm was: If I am slouching, even just a little bit, then I raise the monitor and repeat. There's a subtle but important difference than following suit to standards: I want the monitor height to not only be proper for when I sit straight, but I want it to promote me to sit straight.
The end results were my 22" monitors were positioned so my eye-level, while sitting straight, was about 1/3rd the way down the screen. The top of the screens were well above eye-level. Before, when the top of the screens matched my eye-level, I was still slouching; They were not high enough.
Now that I am done, the monitors feel very high off my desk. People make fun of how high they are.
It created another problem: I want to use arms to hold the monitors, instead of risers which take up all my desk room, and I have not been able to find any inexpensive ones that raise this high. The final height is about 11" off my desk. But, be aware that my desk surface is the level of my keyboard; I have no keyboard tray. My seat is fixed at a height which makes this ergonomically proper.
Hope this bit of personal experience helps.
As described in my other answer, the OSHA guidelines cover pretty much any size monitor. However, people may have an extremely large monitor they want to use from a closer-than-recommended distance, or have unusual workspace constraints, or want to experiment with placement. Here is a useful way to approach monitor positioning if you don't want to follow the OSHA guidelines.
Start with you
Monitor placement begins with the user, not the monitor or its size. The requirements are driven by characteristics of the "human machine". Aligning the top of the screen with where the operator looks straight ahead is based on human physiology, not monitor size.
There are movements that are easy for your body to do and ones that are stressful. Tilting your head up is more stressful than tilting it down. Rolling your eyes up is more stressful than rolling them down. You can look down about 35 degrees without moving your head, and about 60 degrees comfortably if you move your head.
Ignore the monitor for a moment. From a "neutral" position, using good posture and looking straight ahead, it is easy to look from a range of straight ahead to about 35 degrees down. Call that your neutral field of vision. Outside of this range, it is easier to look down than up.
So you have four "bands" to work with:
Anything outside of straight ahead to 60 degrees down will need to consider what you find the most comfortable and any limitations of your workspace.
Add the monitor
Now superimpose the monitor. If the screen is larger than the neutral field of vision, your body will need to do work to look at the rest of the screen. There will not be a perfect setup; you will need to make compromises. The tradeoff is a combination of:
Any "optimum" solution, regardless of monitor size, will involve having very little screen above straight ahead, or below 60 degrees down, although needing to occasionally look in one of those areas may be part of the tradeoff.
Distance
The premise here is that you want to use the screen closer than recommended. If there is any way to work within the OSHA guidelines, that will give you the best result. So before settling for a compromise, challenge your assumptions that you need something different. Look for a way to adjust your constraints. Just sayin'.
If you use glasses and your vision is what's driving a need to use the monitor so close, get a pair of computer glasses, which will give you a full field of vision corrected for the monitor distance you use. This will allow you to move a large monitor a little farther away and compensate for the distance with the prescription. That puts more of the screen within your neutral field of vision.
Positioning content
How you use the monitor can be a major factor in the equation. If portions of the screen must be in places that are stressful to view, it will be tiring and possibly uncomfortable to use for long periods. You can improve the situation by controlling where you place things on the screen. Use the areas outside your neutral field of vision for what you use the least often.
For example, say your situation requires that a small portion of your screen must be above straight ahead. You can choose which content goes there. So say you don't refer to the system tray much. Use a desktop environment that places the system tray at the top of the screen. That frees the bottom of the screen (which would be in a better viewing location), for content used more often.
Incremental adjustment
If you are working outside the OSHA guidelines, don't expect to setup one time and have it be perfect. Start with the general guidelines and make it as close as you can to that. From there, if you find the compromise isn't ideal, adjust to minimize the problems.
I have three 20" LCD's left to right no gaps between the bezels. I find looking left or right more than 1/2 of those outer screen gives me a pain in my neck. For instance I often move the browser to the left screen (using nvidia hotkeys I setup CTRL-1,2,or3) to read an article or documentation. If I have to stay on that page more than about 30seconds my neck starts to have pain. Maybe it's because I sit about 18" away from the main screen. But I think there is a limit to how far you can reasonable turn your head left or right for a period of time. So what I try to do is have the browser use the right 1/2 of the left monitor so I don't have so far to turn.
I'm waiting for the 30" LCD's to come down as I think a single 30" with a decent windows manager will do just as well. Hope this was helpful. Although it was not scientific, just my own experience.
