Mental representation: what can pitch tell us about the distance effect?

Reaction time (RT) profiles for comparing magnitudes (e.g., numbers, physical sizes) are similar - the larger the difference between the compared stimuli, the shorter the RT (distance effect). Nevertheless, it is unclear whether such correspondence is due to similar, two-dimensional, linear mental representations of magnitudes. In contrast, pitch perception has a more complex, two-dimensional, helical representation. This study examined whether comparisons of music pitches are similar to other magnitude response functions. Experiment 1 employed a comparison task, resulting in an RT profile identical to that obtained when comparing other magnitudes. In contrast, Experiment 2 employed a discrimination task, resulting in RTs that matched the helical representation and were dissociated from the classical distance effect. Experiment 3 replicated the results of Experiment 1 using a comparison task with different stimuli and intervals. These findings imply that the distance effect under comparison tasks might reflect a general sensorimotor transformation, rather than mental representation per se.