In the scope of the research project 148/18 - Voice perception in the visually deprived brain: Behavioral and electrophysiological insights, supported by the BIAL Foundation, the research team, led by Tatiana Conde, aimed to explore how blind individuals perceive emotional authenticity. Combining behavioural and ERP measures it was investigated authenticity perception in laughter and crying in individuals early-blind (n = 17) late-blind (n = 17), and sighted control participants (n = 51). Behaviourally, early-blind and sighted participants performed similarly well in emotional authenticity perception, but the late-blind group performed worse than sighted controls. In brain responses, all groups were sensitive to laughter authenticity at the P2 stage, and to crying authenticity at the early LPP stage. Nevertheless, only early-blind participants were sensitive to crying authenticity at the N1 and middle LPP stages, and to laughter authenticity at the early LPP stage. Furthermore, early-blind and sighted participants were more sensitive than late-blind ones to crying authenticity at the P2 and late LPP stages. Altogether, these findings suggest that prolonged visual deprivation with late-onset impairs the processing of emotional authenticity. For more information read the paper Blindness influences emotional authenticity perception in voices: Behavioral and ERP evidence published in the journal Cortex.
ABSTRACT
The ability to distinguish spontaneous from volitional emotional expressions is an important social skill. How do blind individuals perceive emotional authenticity? Unlike sighted individuals, they cannot rely on facial and body language cues, relying instead on vocal cues alone. Here, we combined behavioral and ERP measures to investigate authenticity perception in laughter and crying in individuals with early- or late-blindness onset. Early-blind, late-blind, and sighted control participants (n = 17 per group, N = 51) completed authenticity and emotion discrimination tasks while EEG data were recorded. The stimuli consisted of laughs and cries that were either spontaneous or volitional. The ERP analysis focused on the N1, P2, and late positive potential (LPP). Behaviorally, early-blind participants showed intact authenticity perception, but late-blind participants performed worse than controls. There were no group differences in the emotion discrimination task. In brain responses, all groups were sensitive to laughter authenticity at the P2 stage, and to crying authenticity at the early LPP stage. Nevertheless, only early-blind participants were sensitive to crying authenticity at the N1 and middle LPP stages, and to laughter authenticity at the early LPP stage. Furthermore, early-blind and sighted participants were more sensitive than late-blind ones to crying authenticity at the P2 and late LPP stages.
Altogether, these findings suggest that early blindness relates to facilitated brain processing of authenticity in voices, both at early sensory and late cognitive-evaluative stages. Late-onset blindness, in contrast, relates to decreased sensitivity to authenticity at behavioral and brain levels.
