Dots flash briefly on screen. Count them instantly and select the correct number. Small quantities (1–4) can be perceived at a glance without counting — this is subitizing.
Very Easy
1–4 dots, 1500 ms display — pure subitizing range.
Easy
1–5 dots, 1000 ms display.
Medium
1–7 dots, 700 ms display — enters the counting range.
Hard
1–8 dots, 450 ms — no time to count.
Expert
1–9 dots, 300 ms — requires perceptual estimation.
Scientific Background
Based on: Subitizing & Numerosity Perception (Kaufman et al., 1949; Trick & Pylyshyn, 1994) (Kaufman et al., 1949)