Gender in Voice Perception in Autism

Authors: Wouter B Groen Linda van Orsouw Marcel Zwiers Sophie Swinkels Rutger Jan van der Gaag Jan K Buitelaar

Publish Date: 2008/04/15

Volume: 38, Issue: 10, Pages: 1819-1826

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Abstract

Deficits in the perception of social stimuli may contribute to the characteristic impairments in social interaction in high functioning autism HFA Although the cortical processing of voice is abnormal in HFA it is unclear whether this gives rise to impairments in the perception of voice gender About 20 children with HFA and 20 matched controls were presented with voice fragments that were parametrically morphed in gender No differences were found in the perception of gender between the two groups of participants but response times differed significantly The results suggest that the perception of voice gender is not impaired in HFA which is consistent with behavioral findings of an unimpaired voicebased identification of age and identity by individuals with autism The differences in response times suggest that individuals with HFA use different perceptual approaches from those used by typically developing individualsAlthough impairments in social interaction verbal and nonverbal communication and repetitiverestricted behavior are the more conspicuous defining characteristics of autism American Psychiatric Association 1994 atypical perceptual abilities and responses to stimuli are other characteristic features Gustafsson 1997 Happe 1999 Perceptual discriminative abilities in the auditory and visual domains have been found to be either enhanced or diminished in autism Bertone et al 2005 Samson et al 2006 Many individuals with autism show aversive reactions to everyday sounds Kern et al 2006 Rosenhall et al 1999 and to tactile Cascio et al 2008 and visual stimuli TalayOngan and Wood 2000Knowledge of how stimuli are processed in autism is important for both theoretical and clinical reasons For instance insight into atypical perceptual features may provide a powerful theoretical framework for the perceptual impairments and their neural etiologies in autism Bertone and Faubert 2006 Mottron et al 2006 At a clinical level social perception such as perception of voices and faces is an important channel for nonverbal communication Boucher et al 2000 since both voices and faces contain information about a person’s gender age and emotional states Typically developing neonates respond preferentially to voices Eisenberg 1976 and can recognize the affective content of vocal tones at the age of 6 months WalkerAndrews 1988 underlining the developmental importance of intact perception of social stimuli In contrast children with autism show no preference for their mother’s voices as opposed to other speech stimuli Klin 1991 and show no preference for speech sounds as opposed to electronic sounds Kuhl et al 2005Some authors have argued that the impairments of social perception in autism are an extension of an impaired Theory of Mind in autism ToM Golan et al 2006 Rutherford et al 2002 The ToM theory states that people with autism have a selective difficulty in inferring the mental states of others as measured by False Believe tasks BaronCohen et al 1985 the Reading the Mind in the Eyes Test BaronCohen et al 2001 and the Reading the Mind in the Voice Test Rutherford et al 2002 The latter test requires the affective content of vocalizations to be named which is more difficult for people with autism However these tests do not assess perceptual capabilities but rather test socioemotional and mentalizing skills in autismIn the visual domain several studies have found that when individuals with autism process facial expressions Critchley et al 2000 or neutral faces Pierce et al 2001 Schultz et al 2000 cortical areas outside the fusiform face area are activated areas that are normally activated during the processing of nonface objects In a behavioral study with familiar faces children with autism were less able to identify familiar faces than their typically developing counterparts Boucher et al 1998 Their memory for neutral faces was found to be impaired as well Hauck et al 1998 Yet these studies did not address perceptual abilities per se That is these findings may reflect different perceptual approaches rather than perceptual deficits Support for the theory that individuals with autism have a different perceptual approach comes from the finding that when children with autism look at familiar faces they pay attention to facial features different from those looked at by typically developing children Langdell 1978 Moreover the ability of children with HFA to recognize faces is affected less by face inversion than it is in controls Hobson et al 1988 This suggests that faces are processed analytically in autism rather than holistically as is the case in typically developing childrenWhile less research attention has been paid to the processing of auditory social stimuli the studies performed so far have confirmed the predictions of ToM that mental state inferences based on vocalizations are impaired in autism Golan et al 2006 Rutherford et al 2002 Further the cortical processing of neutral voices Gervais et al 2004 and complex voicelike sounds by individuals with autism Boddaert et al 2003 2004 was found to occur outside the superior temporal sulcus area which is the voiceselective area in normal individuals In contrast nonvocal sounds were processed identically in individuals with autism and controls Thus the pattern of findings for the cortical processing of voices is remarkably similar to that for the cortical processing of faces in autism Yet behavioral studies have not provided clear evidence of an impaired perception of auditory social stimuli that extends beyond mental state related impairments As with the identification of familiar faces children with autism are less able than controls to recognize familiar voices Boucher et al 1998 Yet it is not clear whether these differences reflect perceptualdiscriminatory impairments or postsensory highlevel processes Evidence suggesting that different highlevel processes are activated in autism comes from research showing that the listening preferences of infants with autism tend to be nonsocially directed Klin 1991 Kuhl et al 2005 Moreover children with autism fail to orient to naturally occurring social stimuli including verbal and nonverbal stimuli Dawson et al 1998It is not clear to what extent the abnormal cortical processing of voices reflects perceptual impairments such as gender identification In the visual domain gender perception is affected in autism In a paradigm that required matching videotaped sequences to photographs of men and women individuals with autism were found to have difficulty identifying a person’s gender from their face Hobson 1987 In a more direct paradigm children with autism had greater difficulty identifying the gender of faces in silent movie fragments than controls Giovannelli 2006 Yet in the auditory domain impairments in social perception are mainly due to the inability to recognize emotion in voices Golan et al 2006 Rutherford et al 2002The aim of the current study was to investigate whether the abnormal cortical processing of voices in HFA results in an impaired ability to identify the gender of speakers from their voices Therefore we designed an auditory discrimination task in which voices were parametrically altered in gender such that female voices gradually changed to male voices and vice versa This approach would be very sensitive for detecting differences in the perception of gender since the parametric manipulation avoids ceiling effects that might arise from using just two categories of natural voices ie male or female without gradual overlap We presumed that differences in the perceived gender of a voice between children with autism and controls would reflect perceptualdiscriminatory capabilities Furthermore we recorded response times and presumed that differences in response times would reflect the underlying processes that is we presumed that longer response times would reflect greater task difficulty Specifically longer response times for the control group would imply that the task itself is more difficult while longer reaction times for the HFA group would imply that the participants with HFA find the task more difficult

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