Practice Effects: Why Your Early Scores Go Up (And Why That is Not Cheating)

Practice effects (also called test-retest learning or retest effects) are the improvements in test performance that occur simply from becoming familiar with a test — independent of any underlying cognitive change. When you take a cognitive test for the first time, part of your cognitive load is spent understanding the format, the response requirements, and the timing. As you repeat the test, that overhead decreases, and your scores rise.

This is one of the most robustly documented phenomena in psychometric research. A 2012 meta-analysis in Neuropsychology Review, examining 99 studies of cognitive retest effects, found that practice effects are present across virtually all cognitive task types, are largest on the first two to three retests, and plateau over 5-10 testing sessions. The magnitude varies by task complexity: novel, complex tasks show larger practice effects; simple, familiar-feeling tasks show smaller ones.

If Keel calculated your baseline from early, practice-inflated scores, your apparent baseline would be too high. When your scores eventually plateaued at your true performance level, the model would interpret the stabilization as a decline — a false negative for cognitive health.

Conversely, if Keel ignored the practice effect entirely, your trend line during the early weeks would show artificial improvement, masking any genuine change that might coincide with the learning phase.

Getting this right requires distinguishing between two sources of improvement: practice-driven improvement (which is expected, transient, and uninformative about brain health) and genuine cognitive improvement (which might reflect an exercise program, better sleep, a resolved health issue, or other real cognitive gains).

Keel's baseline model fits a practice effect curve to your early session data. This curve has a known mathematical shape — steep initial improvement that decelerates and flattens — and Keel fits the parameters of this curve to your specific learning rate. Once the practice effect component is modeled, it is subtracted from your raw scores before the baseline is established.

Practically, this means: in your first 7-10 sessions, Keel treats your scores as primarily informative about your practice effect curve, not your stable baseline. Your trend line may show an upward slope during this phase — expected and correctly labeled. After roughly 15-20 sessions, the practice effect has been characterized and removed, and your baseline reflects your underlying cognitive capacity.

Different tasks have different practice effect timescales. Semantic fluency tasks plateau quickly (2-3 sessions), because the core task — naming items in a category — is familiar even if the specific category changes. Spatial memory tasks take longer to plateau because the grid format and sequencing requirement are more novel.

A common question: if my scores are improving after session 20, is that still a practice effect or a real cognitive improvement? After 20 sessions, genuine practice effects are essentially complete for most tasks. Continued improvement at that stage more likely reflects a real change — and that is worth noting.

If you start an exercise program in month two and your processing speed scores begin rising in month three, after your practice baseline is established, that is a genuine signal worth tracking. Keel will display this as an upward deviation from your personal baseline, not a practice artifact.