princeton | This study tested the possible relationship between reported visual
awareness (“I see a visual stimulus in front of me”) and
the social attribution of awareness to
someone else (“That person is aware of an object next to him”). Subjects
were tested
in two steps. First, in an fMRI
experiment, subjects were asked to attribute states of awareness to a
cartoon face. Activity
associated with this task was found
bilaterally within the temporoparietal junction (TPJ) among other areas.
Second, the TPJ
was transiently disrupted using
single-pulse transcranial magnetic stimulation (TMS). When the TMS was
targeted to the same
cortical sites that had become active
during the social attribution task, the subjects showed symptoms of
visual neglect in
that their detection of visual stimuli was
significantly affected. In control trials, when TMS was targeted to
nearby cortical
sites that had not become active during
the social attribution task, no significant effect on visual detection
was found.
These results suggest that there may be at
least some partial overlap in brain mechanisms that participate in the
social attribution
of sensory awareness to other people and
in attributing sensory awareness to oneself.
Significance: What is the relationship between your own private awareness of events
and the awareness that you intuitively attribute to
the people around you? In this study, a
region of the human cerebral cortex was active when people attributed
sensory awareness
to someone else. Furthermore, when that
region of cortex was temporarily disrupted, the person’s own sensory
awareness was
disrupted. The findings suggest a
fundamental connection between private awareness and social cognition.
