Thalen

Your brain, tracked with
scientific precision.

Five validated cognitive tests in five minutes. Your score compares you against your personal baseline, not population averages.

The Scoring System

Your Thalen Score

A chess rating for your brain. Elo solved ranking chess players in 1960. We adapted it for cognition.

Clinical trials measure the average person. You aren't average. Your score compares you to yourself.

Two systems

Readiness is your hardware. Cognition is what you do with it. Both matter. Cognition matters more.

Hardware: CNS Readiness

Is your biological hardware online?

  • Motor speed (SRT)
  • Sustained vigilance (PVT)
  • Stability under load (PVT lapses)

Software: Cognitive Performance

How well is your brain processing?

  • Working memory (N-Back)
  • Executive control (Stroop)
  • Processing throughput (DSST)

The lapse veto

One attention lapse caps your score at 70%. Two or more cap you at 49%.

This isn't punishment. It's reality. If your brain goes offline mid-session, performance metrics don't tell the full story.

Your scoring journey

Days 1-7: Practice effects

You're learning the tests. Scores aren't meaningful yet.

Days 8-21: Finding your baseline

Your brain's normal range emerges. We compare you to yourself.

Day 21+: Circadian model

Your 2pm score isn't judged against your 8am baseline. Your brain has a rhythm. We measure it.

The weights may evolve. The formula will change. The philosophy won't: your brain is infrastructure. Track what matters.

The Cognitive Battery

Five tests from decades of research

Each test in Thalen's battery comes from peer-reviewed cognitive science research. We didn't invent these assessments. We brought them out of the lab and calibrated them to your personal baseline.

Simple Reaction Time

SRT

~30 seconds · Alertness and basic processing speed

Simple Reaction Time (SRT) measures how quickly you can respond to a stimulus. It is the most basic measure of cognitive readiness and the first metric to degrade with fatigue or sleep deprivation.

Methodology

Respond as quickly as possible when a visual stimulus appears. The test presents multiple trials with randomized inter-stimulus intervals to prevent anticipatory responses.

Metrics

  • Median reaction time (ms)
  • Interquartile range (variability)
  • Valid trial ratio (attention quality)

Why it matters

Meta-analytic research (Lowe et al., 2017) found sustained attention shows the largest effect size (g = −0.41) among cognitive domains under sleep restriction. Reaction time degrades predictably with fatigue, making SRT the most sensitive early indicator of impaired cognitive readiness.

Primary Reference

Lowe CJ, Safati A, Hall PA (2017). The neurocognitive consequences of sleep restriction: A meta-analytic review. Neuroscience & Biobehavioral Reviews. doi:10.1016/j.neubiorev.2017.07.010

Psychomotor Vigilance Test

PVT

~90 seconds · Sustained attention and vigilance

The Psychomotor Vigilance Test (PVT) is the gold standard for measuring sustained attention. Developed for sleep research, it detects attention lapses that predict real-world errors. NASA uses the PVT for astronaut readiness assessment on the International Space Station.

Methodology

Respond to randomly-timed stimuli over an extended period. Inter-stimulus intervals vary unpredictably (2-10 seconds) to prevent rhythmic anticipation and measure true vigilance.

Metrics

  • Reciprocal mean RT (1/RT × 1000)
  • Lapse count (responses >450ms)
  • False starts (premature responses)

Why it matters

Basner & Dinges (2011) showed the PVT detects a 19.2% performance decline after extended sleep deprivation, with lapses increasing exponentially. The Toon Health Study (Tanno et al., 2025) of 1,094 older adults found PVT performance predicts mild cognitive impairment risk independent of sleep factors.

Primary Reference

Basner M, Dinges DF (2011). Maximizing sensitivity of the Psychomotor Vigilance Test (PVT) to sleep loss. Sleep. doi:10.1093/sleep/34.5.581

2-Back Working Memory Task

N-Back

~60 seconds · Working memory capacity

The N-Back task measures working memory: your brain's mental workspace for complex thought. You must continuously update, maintain, and compare information in real-time, making it sensitive to cognitive load, stress, and sleep debt.

Methodology

A sequence of stimuli is presented. Identify when the current stimulus matches the one from 2 positions back. This requires simultaneously maintaining recent items, comparing against current input, and updating the mental buffer. We also track lures (near-matches that test your ability to filter interference).

Metrics

  • d' (d-prime) – signal detection sensitivity
  • Updating efficiency – incorporating new information
  • Maintenance stability – consistency across trials
  • Interference resistance – filtering similar distractors

Why it matters

The n-back task reliably measures three core cognitive components: updating, maintenance, and attentional control. Hepdarcan & Can (2025) confirmed high test-retest reliability across age groups and stimulus types, with strong construct validity supporting its use in neuropsychological assessment.

Primary Reference

Hepdarcan E, Can S (2025). Psychometric characteristics of the n-back task: Construct validity across age and stimulus type, internal consistency, test-retest and alternate forms reliability. Current Psychology. doi:10.1007/s12144-025-07318-9

Stroop Interference Test

Stroop

~45 seconds · Executive function and cognitive control

The Stroop test measures executive function: your ability to inhibit automatic responses. When the word "RED" is printed in blue ink, naming the color requires suppressing the automatic reading response, revealing cognitive control capacity.

Methodology

Name the font color of color words while ignoring the word meaning. Trials include congruent (RED in red), incongruent (RED in blue), and neutral conditions. The interference effect is calculated from the RT difference.

Metrics

  • Interference score (incongruent RT - congruent RT)
  • Congruent reaction time
  • Incongruent reaction time

Why it matters

Sleep deprivation increases overall response time but leaves the interference ratio intact (Cain et al., 2011), suggesting executive control mechanisms remain functional even under fatigue. Neuroimaging confirms consistent activation of the right cingulate cortex and left dorsolateral prefrontal cortex during interference processing.

Primary Reference

Cain SW, Silva EJ, Chang AM, Ronda JM, Duffy JF (2011). One night of sleep deprivation affects reaction time, but not interference or facilitation in a Stroop task. Brain and Cognition. doi:10.1016/j.bandc.2011.02.002

Digit Symbol Substitution Test

DSST

~60 seconds · Processing speed and cognitive throughput

The DSST measures processing speed: how quickly you can learn and apply rules. Part of standard neuropsychological batteries worldwide since 1939, it requires simultaneous coordination of visual scanning, motor speed, and working memory.

Methodology

A key shows digit-symbol pairs (1=-, 2=+, etc.). Given a sequence of digits, substitute the corresponding symbols as quickly and accurately as possible. Speed and accuracy both contribute to the score.

Metrics

  • Correct responses (throughput)
  • Accuracy percentage
  • Responses per minute

Why it matters

The DSST's sensitivity stems from requiring multiple cognitive processes simultaneously. Jaeger (2018) argues this multi-domain engagement explains why it detects cognitive dysfunction before domain-specific tests. Recent validation (Williamson et al., 2023) confirms DSST discriminates between cognitive impairment stages and predicts future cognitive decline.

Primary Reference

Williamson M, Maruff P, Schembri A, et al. (2023). Validation of a digit symbol substitution test for use in supervised and unsupervised assessment in mild Alzheimer's disease. Journal of Clinical and Experimental Neuropsychology. doi:10.1080/13803395.2023.2179977

References

Peer-reviewed research

Every test and statistical method in Thalen is grounded in published research. Here are the primary sources we build on.

Lowe CJ, Safati A, Hall PA (2017). The neurocognitive consequences of sleep restriction: A meta-analytic review. Neuroscience & Biobehavioral Reviews, 80, 586-604.

doi:10.1016/j.neubiorev.2017.07.010· Meta-analysis of 61 studies showing sustained attention has largest effect size (g = −0.41) under sleep restriction

Hepdarcan E, Can S (2025). Psychometric characteristics of the n-back task: Construct validity across age and stimulus type, internal consistency, test-retest and alternate forms reliability. Current Psychology.

doi:10.1007/s12144-025-07318-9· Comprehensive psychometric validation of n-back across age groups and stimulus types

Williamson M, Maruff P, Schembri A, et al. (2023). Validation of a digit symbol substitution test for use in supervised and unsupervised assessment in mild Alzheimer's disease. Journal of Clinical and Experimental Neuropsychology.

doi:10.1080/13803395.2023.2179977· DSST validation for detecting cognitive impairment stages

Cain SW, Silva EJ, Chang AM, Ronda JM, Duffy JF (2011). One night of sleep deprivation affects reaction time, but not interference or facilitation in a Stroop task. Brain and Cognition, 76(1), 37-42.

doi:10.1016/j.bandc.2011.02.002· Stroop interference ratio remains stable under sleep deprivation despite RT increases

Tanno S, Tomooka K, Tanigawa T, et al. (2025). Deterioration of psychomotor vigilance and mild cognitive impairment in Japanese community-dwelling older adults: The Toon Health Study. Sleep Medicine, 134, 106669.

doi:10.1016/j.sleep.2025.106669· PVT performance predicts MCI risk independent of sleep factors (n=1,094)

Jaeger J (2018). Digit Symbol Substitution Test: The case for sensitivity over specificity in neuropsychological testing. Journal of Clinical Psychopharmacology, 38(5), 513-519.

doi:10.1097/JCP.0000000000000941· Modern analysis explaining DSST sensitivity through multi-domain engagement

Basner M, Dinges DF (2011). Maximizing sensitivity of the Psychomotor Vigilance Test (PVT) to sleep loss. Sleep, 34(5), 581-591.

doi:10.1093/sleep/34.5.581· Gold-standard PVT research establishing 19.2% performance decline metrics

Dinges DF, Pack F, Williams K, Gillen KA, Powell JW, Ott GE, Aptowicz C, Pack AI (1997). Cumulative sleepiness, mood disturbance, and psychomotor vigilance performance decrements during a week of sleep restricted to 4-5 hours per night. Sleep, 20(4), 267-277.

doi:10.1093/sleep/20.4.267· Foundational PVT research establishing cumulative effects of sleep restriction

Haatveit BC, Sundet K, Hugdahl K, Ueland T, Melle I, Andreassen OA (2010). The validity of d prime as a working memory index: results from the "Bergen n-back task". Journal of Clinical and Experimental Neuropsychology.

doi:10.1080/13803391003596421· Validates d-prime as a working memory measure for n-back tasks

Welford BP (1962). Note on a Method for Calculating Corrected Sums of Squares and Products. Technometrics, 4(3), 419-420.

doi:10.1080/00401706.1962.10490022· Single-pass algorithm for running variance calculation

Stroop JR (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18(6), 643-662.

doi:10.1037/h0054651· Original Stroop interference paradigm - one of psychology's most replicated findings

Wechsler D (1939). The Measurement of Adult Intelligence. Williams & Wilkins.

doi:10.1037/10020-000· Original DSST as part of Wechsler intelligence scales

These tests have been validated across hundreds of studies over decades. For comprehensive reviews, see Lowe et al. (2017) on sleep restriction effects across cognitive domains, Jaeger (2018) on DSST sensitivity, and Hepdarcan & Can (2025) on n-back psychometric validation.

Get early access.

Thalen is coming to iOS first. Join the TestFlight beta and start building your cognitive baseline.

Free. Your data stays on your device. No account required.