Vision plays a calibrating role in discriminating threat-related vocal emotions
The ability to reliably discriminate vocal expressions of emotion is crucial to engage in successful social interactions. This process is arguably more crucial for blind individuals, since they cannot extract social information from faces and bodies, and therefore chiefly rely on voices to infer the emotional state of their interlocutors. Blind have demonstrated superior abilities in several aspects of auditory perception, but research on their ability to discriminate vocal features is still scarce and has provided unclear results. Here, we used a gating psychophysical paradigm to test whether early blind people would differ from individually matched sighted controls at the recognition of emotional expressions. Surprisingly, blind people showed lower performance than controls in discriminating specific vocal emotions. We presented segments of non-linguistic emotional vocalizations of increasing duration (100 to 400ms), portraying five basic emotions (fear, happy, sad, disgust, angry), and we asked our participants for an explicit emotion categorization task. We then calculated sensitivity indices and confusion patterns of their performance. We observed better performance of the sighted group in the discrimination of angry and fearful expression, with no between-group differences for other emotions. This result supports the view that vision plays a calibrating role for specific threat-related emotions specifically.