Tone deaf people may find it harder to read facial expressions or tell whether someone’s laugh is real or fake, research from Goldsmiths, University of London suggests.
A study found that participants diagnosed with congenital amusia (an inherited defect in musical memory, recognition or processing pitch) were less likely to accurately identify silent facial expressions and emotional vocalisations than those with a typical music-processing ability.
And when processing laughter, participants with amusia showed a reduced sensitivity to whether or not the act was authentic. However, they found laughter to be as contagious as those with normal development do.
Goldsmiths psychologists Professor Lauren Stewart and Professor Daniel Müllensiefen, with Dr César F. Lima and colleagues from Goldsmiths and UCL, believe their findings suggest a developmental music disorder is not just an impairment restricted to auditory information, and it can affect socio-emotional cognition in other subtle ways.
In their first experiment, 24 participants were asked to judge the emotion in extracts of emotional speech, based on the patterns heard in the tone of voice. Emotions included amusement, anger, disgust, fear, pleasure, relief and sadness.
They were also tested using nonverbal vocalisations such as crying or screams, as well as a series of silent facial expressions.
Compared to the control group, the study’s 13 amusics were impaired for all stimulus types, including vocal and facial expressions. In addition to showing reduced accuracy, amusic participants gave more ambivalent responses.
The findings also suggest that for amusics, a deficit in understanding vocal emotions isn’t just related to impaired pitch processing, but to a variety of acoustic information, such as amplitude, duration and intensity as well.
In a second experiment, posed laughs, spontaneous laughs and other distractor emotional sounds were intermixed and presented twice. Participants used a rating scale to indicate whether the vocalisations were posed or genuinely felt, and to what extent they were contagious.
Writing in the online Nature journal Scientific Reports, the researchers explain that several regions of the brain implicated in processing socio-emotional information are the same regions of the brain suggested to be abnormal in people with amusia.
Professor Stewart concludes: “Amusia affects a significant number of people - about four per cent of the population. We’ve researched the condition for some time, but little is known about it beyond the musical domain because people with the condition don’t often report other difficulties.
“Previous studies found that amusia can be associated with other impairments outside music, but they’ve focused on speech processing rather than other visual and auditory cues. We recognise that ours is a small study, but as an early indicator it suggests that further work needs to be done on probing the links between the brain’s structure, amusia, and other aspects of socio-emotional processing.”
Impaired socio-emotional processing in a developmental music disorder by César F. Lima, Sophie Scott and Jason D. Warren (UCL), Olivia Brancatisano, Amy Fancourt, Daniel Müllensiefen (Goldsmiths) and Lauren Stewart (Goldsmiths and Aarhus University) was published in the Nature journal Scientific Reports on Tuesday 11 October 2016.