There are four methods of cerebral lateralization to study the different functionalities of the left and right hemispheres. These methods include the sodium amytal test, the dichotic listening test, and functional brain imaging moreover, the relation between handedness and language lateralization method. In the sodium amytal test, patients’ language abilities are assessed by a neurosurgeon before going into surgery. In the sodium amytal test, sodium amytal is injected into the carotid artery on a side of the neck (Pinel, 2009). The injection anesthetizes the hemisphere on that side for a few minutes, which allows capacities of the other hemisphere to be properly assessed (Pinel, 2009). In the dichotic listening test, "Three pairs of spoken digits are presented through earphones; the digits of each pair are presented simultaneously, one to each ear" (Pinel, 2009). An example of this process may be a subject maybe hearing a particular sequence 3, 9, 2 through one ear and at the same time 1, 6, 4 through the other ear; and then the subject will be asked to report all the digits at the end of the sequence. The test reveals that the left hemispere is the one that most people show dominance in because they hear slightly better in their right ear.
In functional brain imaging, while the subject engages in some activity, such as reading, the activity of the brain is monitored by positron emission tomography (PET) or functional magnetic resonance imaging (fMRI) (Pinel, 2009). The relation between handedness and language lateralization is the final method of cerebral lateralization. Studies show that, "The left hemisphere is the dominant hemispere for language-related abilities in almost all dextral [right-handed) and in the majority of sinestrals (left-handed); they also indicate that sinestrals are more variable than dextrals concerning language lateralization" (Pinel, 2009).