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reflective questions in normal subjects. They found that
positive emotional questions evoked more LEMs to the left.
They interpreted this as left hemisphere specialization for
positive emotions and right hemisphere specialization for
negative emotions. However, the lateral eye movement
methodology has been criticized (Erlichman & Weinberger,
1978) .
Research on mood
Observation of mood after hemispheric damage has also
been viewed as supporting the bivalent model. Sackheim et
al. (1982) reported that pathological laughing was more
likely to be associated with RHD and pathological crying was
associated with LHD. Additionally, they found that patients
with right hemispherectomies were judged to be euphoric in
mood, while patients with left hemispherectomies were not.
Also, they examined published case reports of gelastic
epileptics, typified by laughing outbursts during ictal
experience, with either left or right lateralized ictal
foci. They found that ictal foci in gelastic epileptics was
predominately left-sided. Based on previous literature, the
authors suggested that the laughing outburst which occurred
during ictal experience were caused by hyperactivity in the
focal area. These authors concluded that both disinhibition
and excitation cause different manifestations in mood in the
right and left hemispheres.