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Abstract:
Abstract: Observers are often unaware of changes in their
visual environment until attention is drawn to the location of
change. Without focused attention, object representations are
ephemeral and conscious detection of change does not occur. Focused
attention appears to mediate change perception by giving objects
coherence across space and time. To study the relation between
focused attention and aware/unaware perception of change, we
recorded Event Related Potentials (ERPs) from subjects performing a
change blindness task. A complex scene was repeatedly presented for
500 ms, separated by a 300 ms blank mask. After several cycles, a
change was introduced in the scene. Original and modified versions
alternated for 40 flickers (unaware change, unattended location of
change), or until the change was reported. A semantic cue was then
displayed to help subjects identify the changing region. During the
subsequent 30 to 40 flickers, subjects attended to that location
and reported when the change was removed (aware change, attended
location of change). Next, subjects looked for a second change in
the same scene, usually absent (no change, unattended location of
original change). Finally, subjects focused attention at the
location of the original change to report its re-occurrence (no
change, attended location of change). Preliminary analyses suggest
different effects of focused attention, aware, and unaware
perception of change.
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