Tohoku University Cognitive Neuroscience Application Center

The psychological effect of perceiving prices just below a round number—such as ¥198—as perceived as irrationally cheap is known as the price-ending effect. This phenomenon arises from two contributing factors: the left-digit effect, wherein the leftmost digit changes due to a small price drop (e.g., from ¥200 to ¥198), and the image effect, which involves the evocation of a low-price image associated with specific ending digits (such as “8” in Japan).

Shoki Ogata, student of Graduate School of Medicine investigated the neural representations of these two components of the price-ending effect using functional magnetic resonance imaging (fMRI). The results revealed that the left-digit effect were associated with decreased activity in brain regions related to visuospatial processing. Notably, reduced activation in the right dorsal posterior precuneus showed a negative correlation with the irrational perception of cheapness caused by left-digit effect and exhibited negative functional connectivity with the dorsal striatal regions.

These findings suggest that changes in the leftmost digit with a price decrease modulate visuospatial processing. In particular, the right dorsal posterior precuneus appears to be associated with the irrationality induced by left-digit effect and could also play a role in the unconscious promotion of purchase intentions.

The results of this study have been published in the journal Biological Psychology. (Sugiura)

Shoki Ogata and Motoaki Sugiura
The leftmost digit change induces a decrease in brain activity related to visuospatial processing: An fMRI study of the price ending effect
Biological Psychology, 2025; 197:109030 (1-11)
https://doi.org/10.1016/j.biopsycho.2025.109030