Human Reaction Times and Fighting Games, or Why Blocking Isn’t Always Easy

By on May 21, 2015 at 8:11 pm


Frame data matters to some extent in every competitive game. Many of these games, however, lack a static framerate against which to compare these numbers, so any gathered frame values are, at best, a rough estimate of the times that players can expect before the attack in question connects with their character.

Since fighting games do run at a static 60 frames-per-second, we are able to discern the exact fraction of a second that we have to react to any given attack. Infil, on their blog dedicated to helping Street Fighter players transition to Killer Instinct, recently put up an excellent post discussing how human reaction time ties into the latter in particular. Through some simple math, they were able to discern that the average human reaction time of about 265 milliseconds equates to roughly 16 frames in a 60fps game. If you’d like to test your own reaction time to see how you compare to the rest of humanity, you can do so by following this link.

This average reaction time means that any attack with a startup time above 16 frames should afford enough of a gap for a reasonable reaction—blocking, in particular. But Infil makes it a point to note that this reaction speed relies upon a single input from an expected source, like clicking when the screen turns green or, in fighting game terms, blocking an overhead. As soon as other stimuli begin piling onto this single source—lows, throws, potential unblockables that require an entirely different form of defense—things get a lot hairier.

With this in mind, here’s a more FGC-friendly (and I use the word “friendly” quite loosely) reaction speed benchmarking tool designed by Teyah and posted to the Dustloop forums back in January of 2011. Instead of providing a simple red-to-green shift—as offered in the test linked above—to denote when one should press an appropriate button, users of this application are tasked with blocking Millia Rage’s overhead options. That’s all. However, these animations push human reaction times to the absolute limit, thanks to their sheer speed. Don’t flinch when she goes for a low, either, as pressing anything against a low will also count as a hit for Millia. It also counts what Teyah appropriately calls “yomi blocking” as a fault, so you have to actually be reacting to Millia’s animations, not simply guessing.

It’s hard. It’s genuinely hard. Try it for yourself.

In USFIV, Ibuki's overhead has 25 start-up frames.
In Ultra Street Fighter IV, Ibuki’s overhead has 25 startup frames.

These tight reaction times and the number of actual reactions possible is why, in a game like Ultra Street Fighter IV, we occasionally see players not use an overhead for an entire set, and then throw it out after a long string of hits to secure a stun in the final round to take the tournament. The overhead wasn’t even on the radar for the opponent that found themselves on its receiving end, so it hit.

With regards to Killer Instinct in particular, Infil cites various bits of frame data for comparison against the average human reaction time, and there are plenty of things to choose from. From the grab bag of potential examples, they pulled Sabrewulf’s Jumping Slash overhead because, “you execute the move out of a running attack, which also has a low option (Hamstring).” So immediately, a defender has two sources (high and low) to potentially block on reaction. Infil goes on to state that “Jumping Slash has 15 frames of startup, which is already on the low side of the reaction limit, but it also doesn’t have a particularly obvious visual tell until the move is almost ready to hit you. This means Jumping Slash is designed to be mostly unreactable to the average gamer.” In other words, defenders have to read their opponents and predict which option they’ll take and block appropriately before the attack even begins.
These same sort of tight reaction windows occur within the game’s combo-breaking system as well, with light auto-doubles allowing only 14-15 frames to react and manuals offering as few as 5 frames.

This got me thinking about Mortal Kombat X—as plenty of things do at the moment—and the way that 50/50 okizeme dominates the current playing field. This is one of the reasons that a character’s strength (or lack thereof) is so heavily influenced by their ability (or inability) to execute fast overhead and low-hitting attacks that convert into combos.

[The frame data used below is taken from the current PC build of Mortal Kombat X; these numbers may have shifted slightly in either direction due to corrections or slight changes implemented in the most recent console patch.]

Kung Jin's 18 frame overhead
Kung Jin’s 18-frame overhead in Mortal Kombat X

There are certain characters—Bojutsu Kung Jin is an excellent example—who can easily dish out over 30% damage from landing a low or an overhead. Here are the startup times for two of his openers:

  • Back+1 (low) has a 12-frame startup
  • Forward+2 (overhead) has an 18-frame startup

Much like Sabrewulf’s Jumping Slash, these attacks are awfully close to the 16 frames of average reaction time. Add in the threat of a throw and those defending are better off spending meter in order to escape pressure through an armored attack than actually try to block, unless their opponent seems to always go for the same okizeme option.

The takeaway here is that we’ve all probably got faster-then-normal reaction times by now, but we can’t react to everything. This drives home the importance of a varied approach to the offensive side of whatever fighting game you prefer. Don’t always go for a low. Don’t always throw. Be sure to mixup your approach, but also know when to keep some of your options out of the opponent’s mind—like the overhead in the Ultra Street Fighter IV example above—to throw out when they least expect them. And if you get hit with the occasional mixup, don’t get discouraged; we’re all only human.

And don’t forget to head over to Infil’s blog to check out their full post regarding Killer Instinct and reaction times. It’s a great read.

Sources: Infil, Dustloop Forums