On the perceptual generality of the unit-decade compatibility effect

Area of Science:

• Cognitive Psychology
• Numerical Cognition
• Human Perception

Background:

• The prevailing assumption in numerical cognition is that number magnitude is represented holistically on a single mental number line.
• Previous research identified a unit-decade compatibility effect in two-digit number comparison, which contradicts the holistic representation assumption.

Purpose of the Study:

• To investigate the perceptual generality of the unit-decade compatibility effect.
• To determine if the effect is dependent on the specific visual arrangement of digits.
• To challenge the assumption of a holistic analog magnitude representation for two-digit numbers.

Main Methods:

• Replicated the unit-decade compatibility effect using a diagonal presentation of two-digit numbers.
• Compared reaction times for compatible and incompatible trials where decade and unit digit comparisons yielded consistent or conflicting decisions, respectively.
• Controlled for overall numerical distance between compared numbers.

Main Results:

• The unit-decade compatibility effect was successfully replicated with a diagonal digit presentation.
• Compatible trials remained faster than incompatible trials, even when digits were not presented vertically aligned.
• The effect's persistence indicates it is not an artifact of specific perceptual encoding.

Conclusions:

• The unit-decade compatibility effect is perceptually general and not tied to specific visual layouts.
• These findings provide strong evidence against a purely holistic analog magnitude representation for two-digit numbers.
• The results suggest that separate processing of decade and unit components influences number comparison.