Signal Stream
Learn the key. Match symbol to number. The key grows, the clock shrinks.
How to Play
A key appears showing which number pairs with which symbol. Learn it, then a number flashes on screen — tap the matching symbol from the tiles below before the timer runs out.
Every correct match shaves a little off the round clock. Every six correct matches, one more symbol joins the key. The mechanic never changes — only how much of it you have to hold in mind, and how fast.
Signal Integrity is your one resource. A wrong tap or a missed timer both cost you a chunk of it — there's no difference between rushing badly and not being fast enough.
The Science Behind Signal Stream
Signal Stream is a live version of the Digit Symbol Substitution Test, or DSST — one of the most widely used processing speed measures in cognitive and clinical research. The original paper-and-pencil version asks people to fill in as many symbol-number matches as possible in 90 seconds, using a fixed key printed at the top of the page.
Processing speed is a distinct cognitive skill from working memory or attention, even though this task leans on both. It's specifically about how fast your brain can execute a simple, well-defined mental operation — look up the pairing, act on it — over and over, without the rule itself changing.
The escalating key size is doing something specific: it doesn't make any single lookup harder, it makes the search space bigger. Nine symbols to scan through takes measurably longer than four, even though the underlying decision — find the match — is identical. That's the same principle behind Hick's Law, tested elsewhere on the platform in Flash Scan, applied to memory-guided visual search instead of raw choice.
Tips to Improve Your Score
- Don't re-derive the key from scratch every round. The pairings don't change while the key size holds — the faster you commit them to short-term memory, the less time you spend scanning.
- A missed timer costs the same as a wrong tap. There's no reward for guessing fast and wrong over pausing half a second longer to get it right.
- Expect a real slowdown each time the key grows. That's the search space getting bigger, not you getting worse. It's the effect the game is built to demonstrate.
FAQ
What is the DSST?
The Digit Symbol Substitution Test — a widely used clinical and research measure of processing speed, where people match symbols to numbers using a fixed key as fast as they can.
Why does the key keep growing?
A bigger key means a bigger visual search space for the same lookup task, which is what makes processing speed demands climb without changing the rule itself.
Is a wrong tap worse than running out of time?
Timing out costs slightly more Signal Integrity than a wrong tap, but both count as errors — accuracy and speed are being measured together, not traded off.
What ends a run?
Signal Integrity hitting zero. It only depletes on errors, so a clean run can, in principle, continue indefinitely as the key and clock keep escalating.