Ocular drift along the mental number line.

Area of Science:

• Cognitive Psychology
• Neuroscience
• Spatial Cognition

Background:

• The spatial-numerical association (SNA) describes the common tendency to mentally map smaller numbers to the left and larger numbers to the right.
• The underlying mechanisms of SNA, particularly the role of automatic processes and attention, are not fully understood.

Purpose of the Study:

• To investigate the spontaneous association between numbers and space.
• To document attention deployment and the time course of spatial-numerical mapping.
• To examine these associations with and without overt oculomotor responses.

Main Methods:

• Two experiments were conducted involving auditory number presentation.
• Experiment 1: Participants maintained central fixation while listening to number names, with spontaneous ocular drift measured.
• Experiment 2: Participants made saccades following number presentation, with both ocular drift and saccades measured.

Main Results:

• A reliable ocular drift congruent with a horizontal mental number line was observed during and after number presentation in both experiments.
• This effect occurred spontaneously, indicating an implicit and automatic process.
• The findings suggest an oculomotor resonance effect linked to spatial-numerical mapping.

Conclusions:

• The study provides new evidence for the implicit and automatic nature of spatial-numerical mapping.
• Oculomotor activity (ocular drift) reflects the automatic spatial representation of numbers.
• The findings support the existence of an automatic horizontal spatial-numerical mapping mechanism.