Spatial number estimation has a higher linear range than temporal number estimation; differential affordances for...

Area of Science:

• Cognitive Psychology
• Numerical Cognition
• Perception

Background:

• Visuospatial number estimation typically exhibits a limited linear range, often not exceeding 20 items without specific calibration.
• The underlying mechanism for this limitation is debated: capacity constraints of linear accumulators versus strategic subdivision of spatial displays.

Purpose of the Study:

• To investigate whether the limited linear range in visuospatial number estimation is due to accumulator capacity or a subdivision strategy.
• To differentiate between capacity limitations and strategic processing in numerical estimation.

Main Methods:

• Three experiments with 104 undergraduate students assessed number estimation across visual, auditory, and spatial formats.
• Stimuli included temporal numbers (2-58 items), linear spatial numbers, and brief vs. accumulating 2D spatial displays.

Main Results:

• The linear range for visual/auditory temporal numbers was restricted (3-4 items).
• Linear spatial numbers extended the range to approximately 9-10 items.
• Brief spatial displays allowed estimation up to ~20 items, while accumulating displays were limited to ~11 items.

Conclusions:

• The findings indicate that the limited linear range in spatial number estimation is not solely a capacity limitation of linear accumulators.
• Results support a strategy where larger spatial displays (5-20 items) are internally subdivided into potentially subitizable groups.