The time course of person perception from voices in the brain.

When listeners hear a voice, they rapidly form a complex first impression of who the person behind that voice might be. We characterize how these multivariate first impressions from voices emerge over time across different levels of abstraction using electroencephalography and representational similarity analysis. We find that for eight perceived physical (gender, age, and health), trait (attractiveness, dominance, and trustworthiness), and social characteristics (educatedness and professionalism), representations emerge early (~80 ms after stimulus onset), with voice acoustics contributing to those representations between ~100 ms and 400 ms. While impressions of person characteristics are highly correlated, we can find evidence for highly abstracted, independent representations of individual person characteristics. These abstracted representationse merge gradually over time. That is, representations of physical characteristics (age, gender) arise early (from ~120 ms), while representations of some trait and social characteristics emerge later (~360 ms onward). The findings align with recent theoretical models and shed light on the computations underpinning person perception from voices.

Mapping the differential impact of spontaneous and conversational laughter on brain and mind: an fMRI study in autism.

Spontaneous and conversational laughter are important socio-emotional communicative signals. Neuroimaging findings suggest that non-autistic people engage in mentalizing to understand the meaning behind conversational laughter. Autistic people may thus face specific challenges in processing conversational laughter, due to their mentalizing difficulties. Using fMRI, we explored neural differences during implicit processing of these two types of laughter. Autistic and non-autistic adults passively listened to funny words, followed by spontaneous laughter, conversational laughter, or noise-vocoded vocalizations. Behaviourally, words plus spontaneous laughter were rated as funnier than words plus conversational laughter, and the groups did not differ. However, neuroimaging results showed that non-autistic adults exhibited greater medial prefrontal cortex activation while listening to words plus conversational laughter, than words plus genuine laughter, while autistic adults showed no difference in medial prefrontal cortex activity between these two laughter types. Our findings suggest a crucial role for the medial prefrontal cortex in understanding socio-emotionally ambiguous laughter via mentalizing. Our study also highlights the possibility that autistic people may face challenges in understanding the essence of the laughter we frequently encounter in everyday life, especially in processing conversational laughter that carries complex meaning and social ambiguity, potentially leading to social vulnerability. Therefore, we advocate for clearer communication with autistic people.

The Time Course of Person Perception From Voices: A Behavioral Study.

Listeners spontaneously form impressions of a person from their voice: Is someone old or young? Trustworthy or untrustworthy? Some studies suggest that these impressions emerge rapidly (e.g., < 400 ms for traits), but it is unclear just how rapidly different impressions can emerge and whether the time courses differ across characteristics. I presented 618 adult listeners with voice recordings ranging from 25 ms to 800 ms in duration and asked them to rate physical (age, sex, health), trait (trustworthiness, dominance, attractiveness), and social (educatedness, poshness, professionalism) characteristics. I then used interrater agreement as an index for impression formation. Impressions of physical characteristics and dominance emerged fastest, showing high agreement after only 25 ms of exposure. In contrast, agreement for trait and social characteristics was initially low to moderate and gradually increased. Such a staggered time course suggests that there could be a temporo-perceptual hierarchy for person perception in which faster impressions could influence later ones.

Talker and accent familiarity yield advantages for voice identity perception: A voice sorting study.

In the current study, we examine and compare the effects of talker and accent familiarity in the context of a voice identity sorting task, using naturally varying voice recording samples from the TV show Derry Girls. Voice samples were thus all spoken with a regional accent of UK/Irish English (from [London]derry). We tested four listener groups: Listeners were either familiar or unfamiliar with the TV show (and therefore the talker identities) and were either highly familiar or relatively less familiar with Northern Irish accents. Both talker and accent familiarity significantly improved accuracy of voice identity sorting performance. However, the talker familiarity benefits were overall larger, and more consistent. We discuss the results in light of a possible hierarchy of familiarity effects and argue that our findings may provide additional evidence for interactions of speech and identity processing pathways in voice identity perception. We also identify some key limitations in the current work and provide suggestions for future studies to address these.

Unimodal and cross-modal identity judgements using an audio-visual sorting task: Evidence for independent processing of faces and voices.

Unimodal and cross-modal information provided by faces and voices contribute to identity percepts. To examine how these sources of information interact, we devised a novel audio-visual sorting task in which participants were required to group video-only and audio-only clips into two identities. In a series of three experiments, we show that unimodal face and voice sorting were more accurate than cross-modal sorting: While face sorting was consistently most accurate followed by voice sorting, cross-modal sorting was at chancel level or below. In Experiment 1, we compared performance in our novel audio-visual sorting task to a traditional identity matching task, showing that unimodal and cross-modal identity perception were overall moderately more accurate than the traditional identity matching task. In Experiment 2, separating unimodal from cross-modal sorting led to small improvements in accuracy for unimodal sorting, but no change in cross-modal sorting performance. In Experiment 3, we explored the effect of minimal audio-visual training: Participants were shown a clip of the two identities in conversation prior to completing the sorting task. This led to small, nonsignificant improvements in accuracy for unimodal and cross-modal sorting. Our results indicate that unfamiliar face and voice perception operate relatively independently with no evidence of mutual benefit, suggesting that extracting reliable cross-modal identity information is challenging.

Cohesion and Joint Speech: Right Hemisphere Contributions to Synchronized Vocal Production.

UNLABELLED: Synchronized behavior (chanting, singing, praying, dancing) is found in all human cultures and is central to religious, military, and political activities, which require people to act collaboratively and cohesively; however, we know little about the neural underpinnings of many kinds of synchronous behavior (e.g., vocal behavior) or its role in establishing and maintaining group cohesion. In the present study, we measured neural activity using fMRI while participants spoke simultaneously with another person. We manipulated whether the couple spoke the same sentence (allowing synchrony) or different sentences (preventing synchrony), and also whether the voice the participant heard was "live" (allowing rich reciprocal interaction) or prerecorded (with no such mutual influence). Synchronous speech was associated with increased activity in posterior and anterior auditory fields. When, and only when, participants spoke with a partner who was both synchronous and "live," we observed a lack of the suppression of auditory cortex, which is commonly seen as a neural correlate of speech production. Instead, auditory cortex responded as though it were processing another talker's speech. Our results suggest that detecting synchrony leads to a change in the perceptual consequences of one's own actions: they are processed as though they were other-, rather than self-produced. This may contribute to our understanding of synchronized behavior as a group-bonding tool. SIGNIFICANCE STATEMENT: Synchronized human behavior, such as chanting, dancing, and singing, are cultural universals with functional significance: these activities increase group cohesion and cause participants to like each other and behave more prosocially toward each other. Here we use fMRI brain imaging to investigate the neural basis of one common form of cohesive synchronized behavior: joint speaking (e.g., the synchronous speech seen in chants, prayers, pledges). Results showed that joint speech recruits additional right hemisphere regions outside the classic speech production network. Additionally, we found that a neural marker of self-produced speech, suppression of sensory cortices, did not occur during joint synchronized speech, suggesting that joint synchronized behavior may alter self-other distinctions in sensory processing.

Feel the Noise: Relating Individual Differences in Auditory Imagery to the Structure and Function of Sensorimotor Systems.

Humans can generate mental auditory images of voices or songs, sometimes perceiving them almost as vividly as perceptual experiences. The functional networks supporting auditory imagery have been described, but less is known about the systems associated with interindividual differences in auditory imagery. Combining voxel-based morphometry and fMRI, we examined the structural basis of interindividual differences in how auditory images are subjectively perceived, and explored associations between auditory imagery, sensory-based processing, and visual imagery. Vividness of auditory imagery correlated with gray matter volume in the supplementary motor area (SMA), parietal cortex, medial superior frontal gyrus, and middle frontal gyrus. An analysis of functional responses to different types of human vocalizations revealed that the SMA and parietal sites that predict imagery are also modulated by sound type. Using representational similarity analysis, we found that higher representational specificity of heard sounds in SMA predicts vividness of imagery, indicating a mechanistic link between sensory- and imagery-based processing in sensorimotor cortex. Vividness of imagery in the visual domain also correlated with SMA structure, and with auditory imagery scores. Altogether, these findings provide evidence for a signature of imagery in brain structure, and highlight a common role of perceptual-motor interactions for processing heard and internally generated auditory information.

Distinct neural systems recruited when speech production is modulated by different masking sounds.

When talkers speak in masking sounds, their speech undergoes a variety of acoustic and phonetic changes. These changes are known collectively as the Lombard effect. Most behavioural research and neuroimaging research in this area has concentrated on the effect of energetic maskers such as white noise on Lombard speech. Previous fMRI studies have argued that neural responses to speaking in noise are driven by the quality of auditory feedback-that is, the audibility of the speaker's voice over the masker. However, we also frequently produce speech in the presence of informational maskers such as another talker. Here, speakers read sentences over a range of maskers varying in their informational and energetic content: speech, rotated speech, speech modulated noise, and white noise. Subjects also spoke in quiet and listened to the maskers without speaking. When subjects spoke in masking sounds, their vocal intensity increased in line with the energetic content of the masker. However, the opposite pattern was found neurally. In the superior temporal gyrus, activation was most strongly associated with increases in informational, rather than energetic, masking. This suggests that the neural activations associated with speaking in noise are more complex than a simple feedback response.

I thought that I heard you laughing: Contextual facial expressions modulate the perception of authentic laughter and crying.

It is well established that categorising the emotional content of facial expressions may differ depending on contextual information. Whether this malleability is observed in the auditory domain and in genuine emotion expressions is poorly explored. We examined the perception of authentic laughter and crying in the context of happy, neutral and sad facial expressions. Participants rated the vocalisations on separate unipolar scales of happiness and sadness and on arousal. Although they were instructed to focus exclusively on the vocalisations, consistent context effects were found: For both laughter and crying, emotion judgements were shifted towards the information expressed by the face. These modulations were independent of response latencies and were larger for more emotionally ambiguous vocalisations. No effects of context were found for arousal ratings. These findings suggest that the automatic encoding of contextual information during emotion perception generalises across modalities, to purely non-verbal vocalisations, and is not confined to acted expressions.

Left-handed voices? Examining the perceptual learning of novel person characteristics from the voice.

We regularly form impressions of who a person is from their voice, such that we can readily categorise people as being female or male, child or adult, trustworthy or not, and can furthermore recognise who specifically is speaking. How we establish mental representations for such categories of person characteristics has, however, only been explored in detail for voice identity learning. In a series of experiments, we therefore set out to examine whether and how listeners can learn to recognise a novel person characteristic. We specifically asked how diagnostic acoustic properties underpinning category distinctions inform perceptual judgements. We manipulated recordings of voices to create acoustic signatures for a person's handedness (left-handed vs. right-handed) in their voice. After training, we found that listeners were able to successfully learn to recognise handedness from voices with above-chance accuracy, although no significant differences in accuracy between the different types of manipulation emerged. Listeners were, furthermore, sensitive to the specific distributions of acoustic properties that underpinned the category distinctions. We, however, also find evidence for perceptual biases that may reflect long-term prior exposure to how voices vary in naturalistic settings. These biases shape how listeners use acoustic information in the voices when forming representations for distinguishing handedness from voices. This study is thus a first step to examine how representations for novel person characteristics are established, outside of voice identity perception. We discuss our findings in light of theoretical accounts of voice perception and speculate about potential mechanisms that may underpin our results.

Human talkers change their voices to elicit specific trait percepts.

The voice is a variable and dynamic social tool with functional relevance for self-presentation, for example, during a job interview or courtship. Talkers adjust their voices flexibly to their situational or social environment. Here, we investigated how effectively intentional voice modulations can evoke trait impressions in listeners (Experiment 1), whether these trait impressions are recognizable (Experiment 2), and whether they meaningfully influence social interactions (Experiment 3). We recorded 40 healthy adult speakers' whilst speaking neutrally and whilst producing vocal expressions of six social traits (e.g., likeability, confidence). Multivariate ratings of 40 listeners showed that vocal modulations amplified specific trait percepts (Experiments 1 and 2), which could be explained by two principal components relating to perceived affiliation and competence. Moreover, vocal modulations increased the likelihood of listeners choosing the voice to be suitable for corresponding social goals (i.e., a confident rather than likeable voice to negotiate a promotion, Experiment 3). These results indicate that talkers modulate their voice along a common trait space for social navigation. Moreover, beyond reactive voice changes, vocal behaviour can be strategically used by talkers to communicate subtle information about themselves to listeners. These findings advance our understanding of non-verbal vocal behaviour for social communication.

Trait impressions from voices: Considering multiple 'origin stories' and the dynamic nature of trait-related cues.

Experimental findings for trait impressions from voices are often discussed in relation to potential evolutionary origins. This commentary takes Sutherland and Young's (2022) account of the different potential origins of facial trait impressions to suggest that vocal trait impressions should also be viewed as having been shaped by cultural and individual learning.

How do we describe other people from voices and faces?

When seeing someone's face or hearing their voice, perceivers routinely infer information about a person's age, sex and social traits. While many experiments have explored how individual person characteristics are perceived in isolation, less is known about which person characteristics are described spontaneously from voices and faces and how descriptions may differ across modalities. In Experiment 1, participants provided free descriptions for voices and faces. These free descriptions followed similar patterns for voices and faces - and for individual identities: Participants spontaneously referred to a wide range of descriptors. Psychological descriptors, such as character traits, were used most frequently; physical characteristics, such as age and sex, were notable as they were mentioned earlier than other types of descriptors. After finding primarily similarities between modalities when analysing person descriptions across identities, Experiment 2 asked whether free descriptions encode how individual identities differ. For this purpose, the measures derived from the free descriptions were linked to voice/face discrimination judgements that are known to describe differences in perceptual properties between identity pairs. Significant relationships emerged within and across modalities, showing that free descriptions indeed encode differences between identities - information that is shared with discrimination judgements. This suggests that the two tasks tap into similar, high-level person representations. These findings show that free description data can offer valuable insights into person perception and underline that person perception is a multivariate process during which perceivers rapidly and spontaneously infer many different person characteristics to form a holistic impression of a person.

Trait impressions from voices are formed rapidly within 400 ms of exposure.

When seeing a face or hearing a voice, perceivers readily form first impressions of a person's characteristics-are they trustworthy, do they seem aggressive? One of the key claims about trait impressions from faces and voices alike is that these impressions are formed rapidly. For faces, studies have systematically mapped this rapid time course of trait impressions, finding that they are well formed and stable after approximately 100 ms of exposure. For voices, however, no systematic investigation of the time course of trait perception exists. In the current study, listeners provided trait judgments (attractiveness, dominance, trustworthiness) based on recordings of 100 voices that lasted either 50, 100, 200, 400, or 800 ms. Based on measures of intra- and interrater agreement as well as correlations of mean ratings for different exposure conditions, we find that trait perception from voices is indeed rapid. Unlike faces, however, trait impressions from voices require longer exposure to develop and stabilize although they are still formed by 400 ms. Furthermore, differences in the time course of trait perception from voices emerge across traits and voice gender: The formation of impressions of attractiveness and dominance required less exposure when based on male voices, whereas impressions of trustworthiness evolved over a more gradual time course for male and female voices alike. These findings not only provide the first estimate of the time course of the formation of voice trait impressions, but they also have implications for voice perception models where voices are regarded as "auditory faces." (PsycInfo Database Record (c) 2023 APA, all rights reserved).

A model for person perception from familiar and unfamiliar voices.

When hearing a voice, listeners can form a detailed impression of the person behind the voice. Existing models of voice processing focus primarily on one aspect of person perception - identity recognition from familiar voices - but do not account for the perception of other person characteristics (e.g., sex, age, personality traits). Here, we present a broader perspective, proposing that listeners have a common perceptual goal of perceiving who they are hearing, whether the voice is familiar or unfamiliar. We outline and discuss a model - the Person Perception from Voices (PPV) model - that achieves this goal via a common mechanism of recognising a familiar person, persona, or set of speaker characteristics. Our PPV model aims to provide a more comprehensive account of how listeners perceive the person they are listening to, using an approach that incorporates and builds on aspects of the hierarchical frameworks and prototype-based mechanisms proposed within existing models of voice identity recognition.

The effects of the presence of a face and direct eye gaze on voice identity learning.

We rarely become familiar with the voice of another person in isolation but usually also have access to visual identity information, thus learning to recognize their voice and face in parallel. There are conflicting findings as to whether learning to recognize voices in audiovisual vs audio-only settings is advantageous or detrimental to learning. One prominent finding shows that the presence of a face overshadows the voice, hindering voice identity learning by capturing listeners' attention (Face Overshadowing Effect; FOE). In the current study, we tested the proposal that the effect of audiovisual training on voice identity learning is driven by attentional processes. Participants learned to recognize voices through either audio-only training (Audio-Only) or through three versions of audiovisual training, where a face was presented alongside the voices. During audiovisual training, the faces were either looking at the camera (Direct Gaze), were looking to the side (Averted Gaze) or had closed eyes (No Gaze). We found a graded effect of gaze on voice identity learning: Voice identity recognition was most accurate after audio-only training and least accurate after audiovisual training including direct gaze, constituting a FOE. While effect sizes were overall small, the magnitude of FOE was halved for the Averted and No Gaze conditions. With direct gaze being associated with increased attention capture compared to averted or no gaze, the current findings suggest that incidental attention capture at least partially underpins the FOE. We discuss these findings in light of visual dominance effects and the relative informativeness of faces vs voices for identity perception.

The effect of familiarity on within-person age judgements from voices.

Listeners can perceive a person's age from their voice with above chance accuracy. Studies have usually established this by asking listeners to directly estimate the age of unfamiliar voices. The recordings used mostly include cross-sectional samples of voices, including people of different ages to cover the age range of interest. Such cross-sectional samples likely include not only cues to age in the sound of the voice but also socio-phonetic cues, encoded in how a person speaks. How age perpcetion accuracy is affected when minimizing socio-phonetic cues by sampling the same voice at different time points remains largely unknown. Similarly, with the voices in age perception studies being usually unfamiliar to listeners, it is unclear how familiarity with a voice affects age perception. We asked listeners who were either familiar or unfamiliar with a set of four voices to complete an age discrimination task: listeners heard two recordings of the same person's voice, recorded 15 years apart, and were asked to indicate in which recording the person was younger. Accuracy for both familiar and unfamiliar listeners was above chance. While familiarity advantages were apparent, accuracy was not particularly high: familiar and unfamiliar listeners were correct for 68.2% and 62.7% of trials, respectively (chance = 50%). Familiarity furthermore interacted with the voices included. Overall, our findings indicate that age perception from voices is not a trivial task at all times - even when listeners are familiar with a voice. We discuss our findings in the light of how reliable voice may be as a signal for age.

Highly accurate and robust identity perception from personally familiar voices.

Previous research suggests that familiarity with a voice can afford benefits for voice and speech perception. However, even familiar voice perception has been reported to be error-prone, especially in the face of challenges such as reduced verbal cues and acoustic distortions. It has been hypothesized that such findings may arise due to listeners not being "familiar enough" with the voices used in laboratory studies, and thus being inexperienced with their full vocal repertoire. Extending this idea, voice perception based on highly familiar voices-acquired via substantial, naturalistic experience-should therefore be more robust than voice perception from less familiar voices. We investigated this proposal by contrasting voice perception of personally familiar voices (participants' romantic partners) versus lab-trained voices in challenging experimental tasks. Specifically, we tested how differences in familiarity may affect voice-identity perception from nonverbal vocalizations and acoustically modulated speech. Large benefits for the personally familiar voice over a less familiar, lab-trained voice were found for identity recognition, with listeners displaying both highly accurate yet more conservative recognition of personally familiar voices. However, no familiar-voice benefits were found for speech perception in background noise. Our findings suggest that listeners have fine-tuned representations of highly familiar voices that result in more robust and accurate voice recognition despite challenging listening contexts, yet these advantages may not always extend to speech perception. We conclude that familiarity with voices is indeed on a continuum, with identity perception for personally familiar voices being highly accurate. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Audiovisual identity perception from naturally-varying stimuli is driven by visual information.

Identity perception often takes place in multimodal settings, where perceivers have access to both visual (face) and auditory (voice) information. Despite this, identity perception is usually studied in unimodal contexts, where face and voice identity perception are modelled independently from one another. In this study, we asked whether and how much auditory and visual information contribute to audiovisual identity perception from naturally-varying stimuli. In a between-subjects design, participants completed an identity sorting task with either dynamic video-only, audio-only or dynamic audiovisual stimuli. In this task, participants were asked to sort multiple, naturally-varying stimuli from three different people by perceived identity. We found that identity perception was more accurate for video-only and audiovisual stimuli compared with audio-only stimuli. Interestingly, there was no difference in accuracy between video-only and audiovisual stimuli. Auditory information nonetheless played a role alongside visual information as audiovisual identity judgements per stimulus could be predicted from both auditory and visual identity judgements, respectively. While the relationship was stronger for visual information and audiovisual information, auditory information still uniquely explained a significant portion of the variance in audiovisual identity judgements. Our findings thus align with previous theoretical and empirical work that proposes that, compared with faces, voices are an important but relatively less salient and a weaker cue to identity perception. We expand on this work to show that, at least in the context of this study, having access to voices in addition to faces does not result in better identity perception accuracy.