Relative Advantages of Speech vs. Nonspeech in Emotion Perception: Effects of Emotional Category and Attentional Focus

Debates persist regarding whether speech is processed by specialized mechanisms or treated similarly to other auditory inputs. While non-linguistic vocalizations have been reported to take precedence over speech stimuli in conveying emotion, the impacts of attentional demand and stimulus characteristics remain underexplored. This study investigated the relative perceptual advantages of emotional speech and nonspeech stimuli by introducing acoustic control and varying attentional focus. Thirty-seven participants (18 men and 19 women) completed two tasks on spoken syllables and their acoustically matched nonspeech hums. In the emotion identification task, attention was focused on emotional content (angry vs. happy), while in the stimulus type identification task, attention was directed towards stimulus type (speech vs. nonspeech). Unlike previous studies, the results revealed a reversed perceptual advantage in both accuracy and reaction time measures for speech over nonspeech, which was mediated by attentional focus. Speech outperformed nonspeech in emotion identification for both anger and happiness, but this speech advantage was observed only for the angry voice in the stimulus type task. These findings suggest that when basic prosodic cues are controlled, speech might be processed in a more specialized way for emotion recognition, which has important implications for understanding and treating individuals with speech- and emotion-related disorders.