Humans often picture numbers mentally arranged from left to right—small numbers on the left, large on the right. This tendency is called the SNARC effect (Spatial-Numerical Association of Response Codes), and it’s been widely observed in Western cultures.
But is this spatial-numerical mapping a human invention—or a deeper feature of cognition?
What We Do
In our lab, we test nonverbal SNARC-like effects in birds. In one task, birds learn to respond to numerical stimuli by pecking either left or right. The stimuli vary in magnitude (e.g., showing fewer vs. more items), and we look for consistent side preferences linked to number size.
Our findings suggest that while birds do not show a consistent species-level bias, individual pigeons and jays display strong, stable, and idiosyncratic SNARC-like patterns. In other words, some birds always associate “smaller” with left—but others with right.
In parallel work with human participants, we’ve found that SNARC effects also vary widely in both direction and strength, even within Western populations typically assumed to show uniform left-to-right biases.
Why It Matters
This research challenges the idea that spatial-numerical mappings are universal, even within a species. Instead, it highlights individual cognitive diversity and raises new questions about how we learn and represent abstract concepts like number.