Abstract
The combination of different senses is necessary to enhance perception. There exists a hypothesis that correspondences between different modalities are processed automatically in our daily lives and thus seemingly unrelated connections of cross-modal correspondences exist. Cross-modality helps with the efficient processing of information by connecting different modalities. Strong evidence of congruence between shapes and sizes with pitch has been found. Several studies show that with adjustable colour saturation and lightness, the participants will use high values for associations with the high-pitched sound. However, there is still no consensus on the topic of the association between the pitch and hue of the colour. Here we investigate the importance of lightness and show the difference in equiluminant and non-equiluminant stimuli in association to pitch. We found a strong connection between yellow colour with high pitch and blue colour with low pitch in the HSV binary-choice experiments. Contrary to that, the results of the CIELCH binary choice experiment showed a tendency for green hues for high-pitch tones and red for low-pitch. The results showcase a drastic difference in equiluminant and non-equiluminant stimuli cross-modality and support the importance of lightness in the colour-sound correspondences. The use of experiments that test subconscious associations could be a possible way for development since the conscious results correlate heavily to the culture and personal experience than to natural intrinsic cross-modal connections. Based on the results of this work, additional experiments should be conducted with the use of visual stimuli without the influence of lightness. The connection of hue to the sounds that are more complex than pure pitch may be investigated to find further cross-modal associations.