Immediate small number perception: evidence from a new numerical carry-over procedure.

Evidence is presented for the immediate apprehension of exact small quantities. Participants performed a quantification task (are the number of items greater or smaller than?), and carry-over effects were examined between numbers requiring the same response. Carry-over effects between small numbers were strongly affected by repeats of pattern and number identity relative to when displays were from the same response category but contained different numbers. Carry-over effects with large items were less sensitive to both pattern and number identity, even when the numbers in the small and large categories were matched for discriminability. The data suggest that small numbers are immediately apprehended through a direct subitization process distinct from pattern recognition and the apprehension of approximate number.