Recent is more: A negative time-order effect in nonsymbolic numerical judgment

Area of Science:

• Cognitive psychology
• Numerical cognition
• Perception

Background:

• Humans and some animals can estimate quantities without explicit counting.
• Time-order effects (TOEs) are perceptual biases influenced by the temporal order of stimuli.
• Previous research has identified TOEs in various non-numerical judgments.

Purpose of the Study:

• To investigate the presence and characteristics of a time-order effect (TOE) in nonsymbolic numerical estimation.
• To examine the "recent is more" effect in comparative numerical judgment tasks.
• To explore the underlying mechanisms of this numerical TOE.

Main Methods:

• Two comparative judgment tasks were used: larger-smaller discrimination and same-different discrimination.
• Ideal-observer modeling was applied to analyze individual data sets for TOE.
• An estimation task was employed to assess stimulus overestimation.

Main Results:

• A negative time-order effect (TOE), where the second stimulus is overestimated, was found in 88.2% of individual data sets.
• The majority (87.3%) of identified TOEs showed a "recent is more" direction.
• Effect size depended on stimulus magnitude and interstimulus interval, but not task type.

Conclusions:

• A consistent negative TOE exists in nonsymbolic numerical estimation, suggesting a "recent is more" bias.
• Findings indicate a common underlying mechanism for TOEs across numerical and non-numerical judgments.
• Individual differences in effect size are substantial, but the direction of the effect is highly consistent.