Expression.
Research in the past has demonstrated that the right hemisphere of the brain is dominant in the perception and expression of emotion. As a result of crossing of the nervous system, the expectation was that the left side of the face would express emotion more intensely than the right. This was tested by using left and right composite faces, showing them to participants, asking them to rate which of the two faces was more intense. The finding was that participants judges the left composites to be more emotionally intense than the right composites, thus supporting the hypothesis that there is asymmetry in the facial expression of emotion. This finding leads to the conclusion that the right hemisphere is dominant in the perception, expression and general procession of emotional information.
Crossing over of the nervous system occurs at the decussation of the pyramids , this is a site just above the medulla-spinal cord junction at which the nerve fibres from either side of the brain cross over to the contralateral side of the body (Marieb, 1998). This means that the sensory information from the right side of the body goes to the contralateral side of the brain, in this case the left hemisphere, and vice versa. Due to this cross over, each hemisphere has motor control over the contralateral side of the body.
The brain's hemispheres are specialised in their functions, amongst others, the left hemisphere is dominant in language, mathematical reasoning and logical thinking. The right hemisphere is dominant in facial recognition, expression and spatial thinking. These findings that the different hemispheres are specialised in their function have come from experiments performed on those with damage to specific parts of the brain thus being able to isolate the particular damaged area and experiment upon this.
Because the hemispheres are specialised in their functions, the psyhcologists in the past have developed theories on asymmetry in emotional perception and expression. It has been found from previous studies that the right hemisphere is dominant in facial recognition and expression. It has been proposed that the right side of the face is more openly expressive, while the left side of the face is 'private' (Sackheim, Gur, 1978).
Darwin first proposed the importance of expression as a form of communication that had survival value for the human species (Atkinson, Atkinson, Smith, Bem, Nolen-Hoeksema, 1996). Later studies found that there were six distinct emotions that can be reliably recognised universally in the human face. These emotions are surprise, fear, sadness, happiness, anger and disgust.
Furthermore, studies have found that the right side of the face is judged as more similar to the whole face than the left. This was done by constructing left and right composites of faces. A composite is constructed by taking a photo and then splitting the face vertically down the centre line then mirroring the two halves to obtain two whole faces, one the left composite and one the right. The finding that the right side of the face is more similar to the whole face, thus concluding that there was a bias in the perceiver. This was produced by right hemisphere dominance in facial recognition rather than by actual asymmetry in expression (Sackheim & Gur 1978).
Nevertheless, the fact that the subjects can find differences in ...