Ten-Month-Old Infants' Reaching Choices for "more": The Relationship between Inter-Stimulus Distance and Number.

Area of Science:

• Developmental Psychology
• Cognitive Science
• Comparative Cognition

Background:

• Human infants and animals can discriminate visual numerosities.
• Research on visual numerical judgments often focuses on quantity, not set density or inter-stimulus distance.
• The role of set density in infant visual perception is under-investigated.

Purpose of the Study:

• To investigate the influence of set density on visual set selection in 10-month-old infants.
• To determine if infants prefer sets with higher item density (closer spacing).

Main Methods:

• Infants were presented with choices between two visual sets of equal item quantity but varying inter-stimulus distances (set densities).
• Experiment 1: Infants chose between sets with a 1:4 ratio in item distance.
• Experiment 2: Item size and distance were reduced to explore alternative strategies.

Main Results:

• In both experiments, 10-month-old infants consistently selected the sets with higher density (closer item spacing).
• Infants demonstrated a preference for denser arrangements regardless of potential 'select all at once' strategies.

Conclusions:

• Ten-month-old infants show a rudimentary capacity for assessing visual set density.
• This density assessment may function similarly to optimal foraging principles observed in animals.
• Infant density perception might complement their developing numerical representations.