On the reliability of laterality effects in a dichotic emotion recognition task

The present study examined the reliability of a dichotic emotion recognition task under three different conditions presumed to provide different levels of control of attention deployment. Sixty right-handed undergraduate students were randomly assigned to one of the three conditions. The task involved dichotic presentation of words pronounced in an angry, happy, sad, or neutral, emotional tone. The free recall condition applied no attention control. It required participants to report the emotion heard in each ear. Both the monitoring and ABX conditions presumably forced participants to divide their attention equally between the ears. In monitoring, participants were required to indicate when a target emotion was presented to either ear. Finally, the ABX condition required participants to indicate whether the emotional tone of a binaural stimulus matched either of the dichotic stimuli on the same trial. Results showed the expected left ear advantage (LEA). In addition, the monitoring and ABX procedures were found to be somewhat more reliable than the free recall procedure. The present study suggests that control of attention deployment strategies is critical in the reliable assessment of laterality. Issues related to task difficulty and its effect on the reliability and magnitude of laterality effects are also discussed.