Catalog

Exercises

Eight short drills, each training one specific mental skill. One is free forever with no account; the rest open with a sign-in.

Free forever

The Ledger

working-memory updating (verbal/numeric) — holding and updating a running total across a chain of steps.

Track a running total through a chain of plus and minus steps, entirely in your head.

Start exercise Details

The Nets

math-fact fluency via retrieval practice / spaced repetition (a 3-box Leitner system).

Drill multiplication facts with a spaced-repetition system that shows your weak spots more often.

Open exercise Details

The Auditor

attention to detail / error-spotting (proofreading under time pressure).

Spot the one wrong number hidden in a receipt, under time pressure.

Open exercise Details

The Vault

spatial working memory (a Corsi-block-style sequence recall task).

Watch a sequence of lit-up squares, then tap them back in the same order.

Open exercise Details

The Appraiser

estimation and magnitude judgment, with a commit-before-reveal structure (state your guess before seeing the true value, forcing genuine estimation rather than adjustment).

Estimate a real number before it's revealed, and see how close your gut gets.

Open exercise Details

The Briefing

reading comprehension via retrieval, not re-scanning (the passage is not visible while answering).

Read a short passage, then answer questions about it from memory alone.

Open exercise Details

The Switch

cognitive flexibility / task-switching (the "switch cost" paradigm from cognitive psychology).

Switch between two rules on the fly and see the cost it takes on your reaction time.

Open exercise Details

The Signal

inhibitory control / selective attention (a classic Stroop color-word interference task).

Name the ink color, not the word — a classic test of ignoring what a word says.

Open exercise Details