The behaviour of a split brain person is more or less normal as long as he gets inputs from both the right and left body but it drammatically changes if the inputs come from one half body only

Again from the book

Consider the following cases

Mary pours a white powder in her husband's coffee
Marry assumes it is sugar but it is poison
Mary's husband dies

Jane pours a white powder in her husband's coffee
Jane assumes it is poison but it is sugar
Jane's husband does not die

Split brain persons who gots above inputs through the right brain only ( via the left body) declared that Mary is a bad person while Jane is a good one

They stuck to the results without making any interpretation
The same persons changed their mind when the got the above inputs also through the left brain ( right body )