Stimulation Induced Changes in Ratio Scaling Between and Within Hemispheres.

Area of Science:

• Neuroscience
• Psychophysics

Background:

• The psychophysical Power Law describes sensory perception through ratio scaling.
• Understanding hemispheric processing and integration of magnitude estimates is crucial for cognitive science.

Purpose of the Study:

• To investigate if the left and right cerebral hemispheres perform ratio scaling similarly.
• To determine how magnitude estimates from each hemisphere are integrated.

Main Methods:

• Cross-modal matching procedure in right-handed males.
• Tachistoscopic presentation of visual stimuli to one or both hemispheres.
• Olfactory stimuli presented to one or both nares to test integration models.

Main Results:

• Ratio scaling showed minimal hemispheric differences for visual and olfactory stimuli, refuting a dominance model.
• A summation model supported olfactory but not visual integration.
• Inter-hemispheric inhibition did not explain integration.

Conclusions:

• Stimulus-induced cerebral activation influences power function forms (exponents and constants).
• Equivalency of stimulation between hemispheres impacts the goodness-of-fit for ratio scaling.
• Hemispheric processing is more influenced by the amount of stimulation than by inter-hemispheric interaction models.