Introduction: Foreword by Mark D. Rejhon

Blur Busters writes about “Better Than 60Hz” monitors, including our ongoing 480 Hz monitor tests, and we have the 240 Hz GSYNC Input lag Tests. These all push bleeding edge limits of reducing input lag.

Now we visit the human portion of input lag.

Humans take time to react; whether to the starting pistol of a Olympics 100 meter sprint, or an enemy in an online match of Counter Strike: Global Offensive. The best players in the $1-billion-dollar eSports industry push the limits of human reflex, and apparently surprisingly so.

Input Latency Chain: Human Element

Many studies have been on Olympics sprint race reaction times, but few studies exist with reaction times in high-end competitive gaming that involve champion players.

Introducing Marwan Daar

We got a researcher, Marwan Daar, to do some preliminary research on this topic. Marwan Daar, of York University (Toronto, Canada), has written several vision research papers (ResearchGate profile) and participates in many online discussion forums under the nickname spacediver, so readers may be familiar with him.

He has written a special article for Blur Busters on human reflex. Needless to say, some data points are eye-opening, with apparent sub-100-millisecond results that certainly merit further detailed study.

Begin reading Marwan Daar’s article: Input Lag and the Limits of Human Reflex, Part 1

8 Comments For “Input Lag and the Limits of Human Reflex”

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Can’t edit: Oh and in audio I’m absolutely always sub 100ms and generally sub 90ms with whatever lag my hardware has, non startle response, never tested that, don’t even know how to test that without potentially harming my ears.

Maybe the zoned out sub 120ms visual results are a form of startle; i have to kinda focus on zoning out and telling myself to just react, sort of mentally binding any change -> react (and I don’t click then, it’s more like my whole body suddenly tenses, and I’ll react to ANY change; dog barks, something happens outside, whatever, I’ll react in that state)

Why did I do this? I was curious how fast I can go and trying to get past what appeared to me my hard limit for conscious reaction of 123ms no matter my state no matter the day I never saw anything faster than 123ms, and tried alternative approaches (without changing hardware). At first I doubted the results when I saw 109 and 103ms occasionally, assuming I had predicted it, but eventually I found I could get into this state more consistently (but never really consistent), and had runs with 3 or 4 sub 120ms results.

Interestingly there is also more variance in this zoned out repsonse; I might get 99ms then 115m, while my conscious reaction time is highly consistent so long as I’m not tense or exhausted.


I am 39 and I test 130-150ms average, assuming I’m not tired etc. I did it right now and got 143ms average with 136ms best time 147ms worst. I had 4 hours sleep today but I’m not really tired.

Sometimes I can sort of zone out and get 3 or 4 times sub 120ms. These aren’t practically useful for games, I feel like I’m somehow bypassing some part of normal processing; I’m only consciously aware of the colour change after I’ve already clicked, unlike my normal 130-150ms times where I feel the click is a conscious action after seeing the colour change.

Furthermore there is the signal path length; I am just over 183cm tall. I have a naturally longer path length for the signal than some one who is 150cm tall with proportionally shorter arms, or a small child.

My averages dropped about 10ms when upgrading from a shitty 144hz benq to 280hz with excellent response times. I also dropped another ~8ms averages when changing to an optical switch mouse, so that’s ~18ms drop going from “very good” to “even better” hardware.

The 270ms average figure is complete nonsense: I just did the test on my phone: over 300ms. The averages there mean nothing and I honestly believe that very few people havea reaction time worse than 200ms in reality.

Also reaction time does not get meaningfully worse with age until a certain point, which depending on lifestyle is typically around 60-85 years old. Forgot where I found the study, but that was my rough takeaway from it (there are exceptions ofc).


Great work and interesting article. I have a few criticisms and some insight:

For the most part you only stress reaction time in relation to input lag, but perception and cognition is also extremely important. From taking the A/B input lag test someone made on the forums here, myself and a friend were able to pass the test down to recognizing a 5ms difference. From playing games with varying levels of input lag it is clear that just feeling a small amount of input lag despite a consistently high fps plays a major factor in coordination.

Regarding your tests, I play at a similar level so I can offer some additional input. I agree that oftentimes this type of aim isn’t conscious. Pattern recognition definitely plays a part. There’s a phenomenon amongst pro play in quake and many other fps games that sometimes standing still is the best dodge to make in certain situations because it’s the least predictable. I look like the end of frag4 is prediction based on the charts and opponent’s movement pattern. It’s worth noting that dodging is also reaction based and you may have been subconsciously trying to move the opposite way of his beam (tough with latency) and forced into a pattern. It might be worth blinding the dodger if you don’t completely randomize it or getting someone skilled at dodging. The fact that dodging is a skill of varying degrees even amongst pros points towards patterns playing a major role as well. I’d say that movement patterns with aiming usually work in that a movement can be highly anticipated, but still reacted upon instead of proactively aiming.

One thing to note is the LG has a knockback effect that is used to control the opponent’s movement to your advantage, but I think that can be disabled in custom game settings. I’m not sure if you did that. You’re correct to note the inertia of movement plays a role, but also notice that player animations clue in the shooter of the intended direction change. I think your method of accounting for the moment deceleration starts isn’t affected by that though.

It’s also worth noting that a player’s mouse movement may intentionally not follow the opponent. Take for example a player strafing to the right of your screen, ideally you want to track the left side of their body, so when they switch directions you don’t have to move your mouse much if at all (and they’re walking into your knockback) while you see if they’re going to continue their direction change or go back in their original direction.

I hope some of this helps, and again, really interesting article.


Even 1ms differences are noticeable as a difference, and even sub 1ms differences are considering some 1k vs 4k vs 8k tests. I find it too stressful to notice 2ms change consciously in an AB test. I don’t have the patience to do 20 runs like that in one sitting. However I can clearly notice 2ms change in a game because of all the timings and overall coordination; something just feels really off when going from mouse input on a seprate thread in OW2 to CS hardcapped at 400fps, which in theory is a touch over 2ms higher latency… but it feels really wrong for about half an hour to an hour till I get used to it. Then the better input feels off till I get used to it (but it does feel subjectively better and snappier, even if I perform worse with it till I adapt).

Also there’s this: input AB testing, you don’t even need 1ms response etc to feel a 1ms difference.