Cerebral lateralization is a relatively new area of study which has important implications for the analysis of the relationship between cognition and emotion. The study of the functions of the left hemisphere and the right hemisphere suggests that there are different kinds of cognition, that is to say, different ways of knowing reality.
The research of cerebral lateralization has dug up evidence that each of the cerebral hemispheres is associated with different kinds of cognition. The left hemisphere is analytic, breaking sense data into meaningful pieces which are equivalent to one another; it is also linear and tend to organize these pieces into sequences, and symbolic, in that it is adept to attaching sense data to learned shapes and sounds. These abilities explain the great importance of the left hemisphere in the control of language. In most people, when the left hemisphere is damaged in certain places, crippling desorders of language result, such as aphasias.
Cerebral lateralization of the right hemisphere, in contrast, is associated with a wholistic, synthetic sort of cognition, which has been termed syncretic cognition (Tucker, 1981). Tucker suggests that this provides an integration of sensory information from different channels, such as visceral, visual, auditory, tactual, etc, into a superordinate conceptualization. There is much recent evidence which suggests that the right hemisphere plays a special role in both the expression and recognition of emotion. Input of the subcortical and limbic system mechanisms associated to higher brain structures is lateralized. Thus important fiber systems associated with motivation and emotion, such as the medial forebain bundle, are right-lateralized.
The left side of the brain has abilities and attributes which could be likened to the functioning of a computer, as it receives, stores and processes information fed into it from external sources. Its working out methods are primarily of a binary either/or, yes/no, accept/reject nature and are strictly logical in the sense that they use the in-coming information in an ordered, predictable manner within definite, limited parameters. The left hemisphere function could be described as passive in that its operation is predominantly reactive. It can never generate from itself any process or task for which it does not have already introduced, or memorized, data.
Through the observation of cerebral lateralization it has been found that the left hemisphere feels secure in the continuity of a process. It does not question how the inception of the process came about, or whether the continuation of it is still valid, and does not care to contemplate the ending of it. The stability of the indefinite continuing is sufficient in itself so that the left will tend to fear, and hence resist, any threat of discontinuity. However, the right hemisphere is the vehicle for change, as it is the medium for such phenomena as creative thinking, initiatives, enterprise and inspiration. In fact, without the left having been conscious of it, the right will have been responsible for initiating many of the processes which the left then tenaciously continues.
In a mature and healthy human being, the right side will initiate reasonable and beneficial processes, will lend support to valid and proven processes, and, with resolution, terminate those which have passed their usefulness or, even worse, have become definitely harmful to the physical and mental well-being.
Whereas the left likes to define, categorize, and concretize the particular as separate, definite and contained, the right seeks always to synthesize and integrate, since it regards relationship not as evidence of multiplicity, but over-riding unity. It will not be satisfied with anything less than the whole meaning.