Evaluation of a novel translational task for assessing emotional biases in different species.

Changes in the processing of emotional information are key features of affective disorders. Neuropsychological tests based on emotional faces or words are used to detect emotional/affective biases in humans, but these tests are not applicable to animal species. In the present study, we investigated whether a novel affective tone discrimination task (ATDT), developed to study emotion-related behaviour in rats, could also be used to quantify changes in affective states in humans. To date, the methods used in human neuropsychology have not been applicable to animal experiments. Participants completed a training session in which they learnt to discriminate specific tone frequencies and to correctly respond in order to gain emotionally valenced outcomes, to obtain rewards (money), or to avoid punishment (an aversive sound clip). During a subsequent test session, additional ambiguous probe tones were presented at frequencies intermediate between the reward and avoidance paired tones. At the end of the task, participants completed self-report questionnaires. All participants made more avoidance responses to the most ambiguous tone cues, suggesting a bias towards avoidance of punishment. Individual differences in the degrees of bias observed were correlated with anxiety measures, suggesting the task's sensitivity to differences in state anxiety within a healthy population. Further studies in clinical populations will be necessary to assess the task's sensitivity to pathological anxiety states. These data suggest that this affective tone discrimination task provides a novel method to study cognitive affective biases in different species, including humans, and offers a novel assessment to study anxiety.