Simultaneous masking in a dichotic emotion detection task.

The present study investigated the possible role of ceiling effects in producing laterality effects of small magnitude in dichotic emotion detection. Twenty two right-handed undergraduate students participated in the present experiment. They were required to detect the presence of a target emotion in the expressions tones of happiness, sadness, anger, and neutrality presented dichotically. Stimuli were adjusted to 70 dB and occurred simultaneously with a white noise mask that had an intensity of 65, 70, 80, or 85 dB. Results showed a left ear advantage (LEA) for the 65 dB mask and a right ear advantage for the 85 dB mask, but only after two testing sessions. The possible existence of a generalized right ear bias that might affect the observed LEA for non-verbal tasks is discussed. Alternative explanations and limitations of the present experiment are also presented.