The left hemisphere’s thinking, specialized in symbolization and demonstration, Aristotle’s proof (pistis), is a discursive thinking that acts differently whether it deals exclusively with signs of essence (it is then called analytical thinking, and the symbol is its major sign) or with an heterogenous set of signs, essential and existencial (it is then called reflective thinking, and it has reductive iconicity as its major rule).
The right hemisphere’s thinking, specialized in indexicalization and illustration, Aristotle’s opinion (gnômê), is a holistic thinking that acts differently whether it deals exclusively with signs of existence (it is then called somatic thinking, and the index is its major sign) or with a combination of signs (it is then called imaginative thinking, and it has instaurative iconicity as its major rule).
The four modes of thinking correspond to the parts of the person as psychology defines them : the Ego is the product of analytical thinking, the Super-Ego a product of imaginative thinking, the Id corresponds to the somatic thinking and self consciousness to reflective thinking. Psychosemiotics and neurosemiotics will then define the Super-Ego as an indexicalization of the Ego symbol, the Id as a production of indexes and the self consciousness as the symbolization of mental indexes.
Discursive thinking tends to subordinate image to concept, opinion to proof, in the process of shaping a language of truth, but holistic thinking, urged by the desire to believe, circumvents that order and lets the image function as a concept.