Human Split Brain Study

Decent Essays
I will reorganize this question to three big components with a different order compared with

the original one: 1) my opinion on whether the left and right hemisphere will response the same

or differently to faces on the left and right visual field; 2) differences and relationships between

the left and right hemisphere in processing faces; 3) explanation of my opinion for 1).

3.1 My point of view

In my opinion, either when the faces are presented in the left or right visual field, the

responses of left and right hemisphere will both be different.

3.2 Left and right hemisphere in processing faces

We know from the anatomical and functional results that human vision obeys the

hierarchical rule from posterior to anterior, with the
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Split brain studies provided a

great opportunity to understand how the two hemispheres different in face processing. Split brain

monkey study has provided a general idea that the left hemisphere is better at distinguishing tiled

lines and the right hemisphere is better at discriminating faces (Hamilton & Vermeire, 1988).

Human split brain case on face processing provided a more detailed result that left hemisphere

showed a recognition bias for self and the right hemisphere showed a bias for familiar others

though both hemispheres are capable of face recognition (Turk et al., 2002). Moreover, results

from cataracts patients showed that the visual information input of faces to the left eye (right

hemisphere) is crucial in normal face processing development (Le Grand et al., 2003). Early

human imaging study showed a lateralization of processing faces in the right hemisphere and

letters in the left hemisphere (Puce, Allison, Asgari, Gore, & McCarthy, 1996b). Later imaging

study on this topic showed left hemisphere was involved in processing “low-level” face

semblance, and perhaps was a precursor to categorical “deep” analyses on the right (Meng et
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The other

model is that the two hemispheres exchange and utilize information symmetrically at early stages

of visual processing. A study (Yovel, Levy, Grabowecky, & Paller, 2003) recorded event-related

potentials (ERPs) to centrally presented face stimuli in which relevant facial information was

presented bilaterally or only in the left (left face) or the right (right face) visual field. The

behavioral results showed the best performance for the faces presented bilaterally, and the better

performance for the left than the right face. ERP results showed no evidence of asymmetric

transfer of information between the hemispheres at early stages of visual processing, and a

shorter latency of the face-specific N170 component to the left than the right face together with a

larger amplitude at 220–280 and 400–600 msec over both hemispheres, indicated that the two

hemispheres symmetrically exchange facial information early in visual processing and generated

collaboration in a shared facial representation, in which facial information that is
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