Abstract The spatial–musical association of response code (SMARC) effect refers to better performance when low-pitch tones are mapped to lower/left response locations and high-pitch tones to upper/right response locations than vice versa. The SMARC effect is robust when response locations vary along the vertical dimension, but it occurs in more limited situations when responses vary along the horizontal dimension. The current study was designed to investigate two factors that have been previously shown to influence the horizontal SMARC effect, tone laterality and musical training, when properties of the tones were task irrelevant. Experiments 1 and 2 found that only musicians showed a robust horizontal SMARC effect when tones were presented binaurally, but both musicians and nonmusicians showed the effect when tones were presented monaurally in all trials. The horizontal SMARC effect was eliminated among nonmusicians when the monaural tone's lateral information was diluted by intermixing of monaural and binaural trials. Experiment 3 showed that 600 trials of practice with a compatible mapping of low pitch to left location and high pitch to right location was sufficient to elicit the horizontal SMARC effect in a transfer session among nonmusicians. Together, the results of the present study confirmed that musicians directly associate pitch height with left–right locations on the horizontal dimension, but for nonmusicians this association is not automatic. For nonmusicians, a horizontal reference frame provided via tone laterality or extensive training to associate pitch with left–right responses is needed for the horizontal SMARC effect to emerge.
Zhong et al. (Thu,) studied this question.