Large sounds and loud numbers? Investigating the bidirectionality and automaticity of cross-modal loudness-number interactions.

This article investigates the cross-modal interaction between loudness and numerical magnitude within the framework of A Theory of Magnitude (ATOM), which posits a shared cognitive representation for different magnitudes such as space, time, and quantity. Across three experiments, participants classified visually presented numbers accompanied by tones of varying loudness to examine whether loudness influences number processing automatically, bidirectionally, and how processing speed affects this interaction. Results consistently showed faster reaction times when the magnitude of loudness and number matched (e.g., large numbers with loud tones), supporting a bidirectional and partly automatic loudness-number interaction. However, the influence of stimulus distance on this interaction was inconsistent, suggesting possible asymmetries in how loudness and number magnitudes affect each other and indicating that external factors like attentional salience modulate the effect. Overall, findings support the inclusion of loudness as a magnitude dimension represented in the shared magnitude system proposed by ATOM, while highlighting complexities in the mechanisms underlying cross-modal magnitude interactions.