Hemispheric Lateralisation and Evaluation

Hemispheric lateralisation

Refers to the division of functions between the two hemispheres

Hemispheres

Brain is split into two hemispheres. Connected by the corpus callosum, nerve fibres that allow interhemispheric communication (allow the hemispheres to send messages)

What is the left hemisphere’s function?

Processes language. Broca’s area (speech production) and Wernicke’s area (language comprehension)

What is the right hemisphere’s function?

Processes visual information. Spatial information is lateralised

A strength of hemispheric lateralisation

Research supports the concept of hemispheres having different functions. Fink et al (1996) used PET scans to identity which brain areas were active for a visual processing task. Regions of the right hemisphere were active when participants were asked to look at an image. Left hemisphere was active when told to focus on finer details in the image. Suggests hemispheric lateralisation is a feature of the connected brain

A limitation of hemispheric lateralisation

Contradictory findings. Language may not be restricted to the left hemisphere. Turk et al (2002) discovered a patient who suffered damage to the left hemisphere, developed the capacity to speak in the right hemisphere. Suggests that lateralisation isn’t fixed and the brain can adapt

Another study for the limitation

Has been suggested that lateralisation isn’t as simple and can change with age. Szaflarski et al (2006) found that language became more lateralised to the left hemisphere with increasing age, after 25, lateralisation decreases. Causes questions on whether if everyone has one hemisphere that is more dominant than the other and if dominance changes with age. Implies that a lateralised brain is only for young adults