Exploring bias in horizontal and vertical spatial representations using mental number lines and the greyscales task

Area of Science:

• Cognitive Psychology
• Neuroscience
• Visuospatial Cognition

Background:

• Individuals display a leftward bias in visuospatial judgments of horizontal stimuli (pseudoneglect) and a superior bias for vertical stimuli.
• The leftward bias in physical space appears to translate to mental representations, but vertical mental space biases remain unexamined.

Purpose of the Study:

• To investigate visuospatial biases in the mental representation of vertical space.
• To determine if biases in mental representations of horizontal and vertical space correlate with biases in physical space.

Main Methods:

• 171 participants judged numerical intervals, visualizing numbers as houses on a street, floors of a building, or with no imagery.
• Replicated findings using greyscales tasks to assess physical space biases.

Main Results:

• A leftward bias was observed when participants visualized numbers as houses on a street.
• No superior bias was found when visualizing numbers as floors of a building.
• Previous findings of leftward and superior biases were replicated using greyscales tasks.

Conclusions:

• The default mental representation of numbers is horizontal and ascending from left to right.
• The spatial biases observed in physical space do not consistently transfer to mental representations of vertical arrangements.