The Journal of Neuroscience, 2000, 20:RC64:1-4
RAPID COMMUNICATION
The Left Hemisphere's Role in Hypothesis Formation
George
Wolford,
Michael B.
Miller, and
Michael
Gazzaniga
Psychology Department, Dartmouth College, Hanover, New Hampshire
03755
In a probability guessing experiment, subjects try to guess which
of two events will occur next. Humans tend to match the frequency of
previous occurrences in their guesses. Animals other than humans tend
to maximize or always choose the option that has occurred the most
frequently in the past. Investigators have argued that frequency
matching results from the attempt of humans to find patterns in
sequences of events even when told the sequences are random. There is
independent evidence that the left hemisphere of humans houses a
cognitive mechanism that tries to make sense of past occurrences. We
performed a probability guessing experiment with two split-brain
patients and found that they approximated frequency matching in their
left hemispheres and approached maximizing in their right hemispheres.
We obtained a conceptual replication of that finding on patients with
unilateral damage to either the left or right hemisphere. We conclude
that the neural processes responsible for searching for patterns in
events are housed in the left hemisphere.
Key words:
split-brain patients; interpreter; decision making; probability matching; maximizing; hypothesis generation
Copyright © 2000 Society for Neuroscience 0270-6474/00/$05.00/0