How the Blind Hear Colour

Area of Science:

• Psychology
• Neuroscience
• Sensory Perception

Background:

• Crossmodal correspondences, like colour-tone mapping, are common in sighted individuals.
• These associations link seemingly independent sensory experiences.

Purpose of the Study:

• To investigate colour-tone mapping in people with congenital blindness and compare it to sighted trichromats.
• To understand the role of sensory experience versus semantic understanding in crossmodal perception.

Main Methods:

• Participants (sighted trichromats and congenitally blind individuals) matched pure tones to named colours.
• Tones of varying pitch were presented and participants selected a corresponding colour.

Main Results:

• Both groups demonstrated consistent colour-tone mapping.
• Congenitally blind individuals did not differentiate red and green tones, unlike sighted participants.
• Lighter colours were consistently associated with higher pitches, and darker colours with lower pitches, across both groups.

Conclusions:

• Colour-tone mapping appears to be influenced by semantic understanding, particularly in individuals without prior visual experience.
• The findings support a link between pitch and lightness perception, potentially mediated by conceptual knowledge.