Table 1 Characteristics of the studies included in the review

Dennis et al. [40]

Retrospective cohort study

Journal of the International Neuropsychological Society

Canada and USA

Pictures of scenarios presented in forms of literal truth, ironic criticism and empathic praise as indicated by audiotapes of speaker’s utterances with neutral, ironic or empathic intonation. Participants were asked about facts and beliefs and to identify the intent of the speaker indicated by their tones

Participants must identify the intent of the speaker as indicated by their tones

Cognition, conation, identifying empathy and irony through prosody

While irony and empathy were presented through audio, the scenarios were delivered via pictures.

Dimoska et al. [38]

Retrospective cohort study

Journal of the International Neuropsychological Society

Australia

To assess participant's perception of emotion in voice, they completed two discrimination tasks using spoken sentences that varied in the amount of semantic information: that is, (1) well-formed English, (2) a nonsense language, and (3) low-pass filtered speech producing "muffled" voices. Participants also completed neuropsychological tests measuring impulsivity, cognitive/executive functions and inhibition of prepotent, automatic response

Materials: (1) audios of semantically well-formed or non-sense sentences with good phonetics and prosody spoken in various emotions and (2) muffled sentences without semantics and intact pitch/contour. Procedures: (1) same/different judgments for emotions portrayed by muffled and non-sense sentences and (2) identify emotional tone using prosody only or with semantics

Emotion recognition from voice

Small sample size, heterogeneous study population

Ietswaart et al. [36]

Prospective cohort study

Neuropsychologia

UK

(1) Labelling facial expressions and labelling morphed facial expressions, (2) labelling emotions from prosody and prosodic discrimination, (3) assessments for language comprehension deficits, (4) assessment of mental speed and pre-morbid intelligence and (5) test of depression and anxiety

(1) Emotional prosody discrimination: neutral sentences spoken in same/different emotional tone, (2) labelling emotions of neutral sentences spoken different emotional tones and (3) non-emotional prosody discrimination: sentences spoken in interrogative or declarative tone

Emotional recognition from face and prosody, depression and anxiety

Limited information for lesion analysis

McDonald and Saunders [39]

Retrospective cohort study

Journal of The International Neuropsychological Society

Australia

Ambiguous or neutral scenarios depicted in emotional (happy, surprised, angry, sad, fearful, disgusted) or neutral format. The emotional stimuli were presented via (1) audiovisual, (2) “still” photographs, (3) dynamic visual and (4) audio-only. Participants were presented with all four formats and asked to label emotions

Identifying emotions portrayed in audio and audio-visual format

Emotion recognition through various media formats

Controls had significantly more years of education than TBI

Milders et al. [37]

Retrospective cohort study

Journal of Clinical and Experimental Neuropsychology

UK

Participants were assessed for (1) emotional and behavioural consequences, (2) home integration, social integration and work integration (employment), (3) recognition of facial expression, (4) understanding intentions and social situation and (5) recognition of emotional prosody

Prosody discrimination: pairs of neutral sentences spoken in same/different (a) non-emotional tones and (b) emotional tones, (c) labelling emotional prosody and (d) labelling emotions when semantics conflicted with prosody

Emotional/behavioural issues, social integration, emotion recognition (face and prosody)

Small sample size, possible biased recruitment method

Schmidt et al. [33]

Prospective cohort study

Neuropsychologia

USA

Participants were assessed on recognition of emotions from voice and visual cues. They also did 2 control tasks, one that tests phonological discrimination and the other for face identity recognition

(1) Emotional prosody task: indicate emotions portrayed in audio of 4 semantically neutral sentences spoken in different emotional prosody and (2) phonological discrimination: match/non-match judgments made for 2 non-sense words that were identical or varied by a single phoneme

Labelling emotions from prosody and face, phonological discrimination

Only used one emotional prosody task, with limited trials

Schmidt et al. [34]

Prospective cohort study

Brain injury

USA

All were assessed on labelling emotional prosody, phonological discrimination and cognitive/neuropsychological tests at baseline and 3 months and underwent MRI at 3 months. DTI analysis was performed to investigate tracts that connect brain regions associated with emotional prosody

(1) Emotional prosody task: identify audio of neutral sentences spoken in different emotional prosody and (2) phonological discrimination: same/different judgments made for pairs of non-words that were identical or varied by a single phoneme

Emotional prosody recognition, phonological discrimination. Quantitative DTI variables

(1) Restricted to participants in a relatively acute stage of recovery and (2) did not take into account mechanism of injury

Zupan and Neumann [35]

Retrospective cohort study

Journal of Head Trauma Rehabilitation

USA

(1) Unimodal: facial affect recognition, (2) unimodal vocal affect recognition and (3) affect recognition from context-enriched multimodal medium. Participants were asked to identify emotions

(2) Vocal affect recognition (Diagnostic Analysis of Nonverbal Affect 2 -Voices): repetitions of neutral sentence spoken different emotional tones. Participants asked to indicate emotion portrayed

Recognition of emotions through voice, face and multimodal medium

No direct comparison for multimodal task (novel method); did not collect data on psychiatric issues