| |
Abstract:
Abstract: Covert orienting paradigms present individuals with
target stimuli that are preceded by valid or invalid spatial cues.
When valid cues are presented peripherally at the target location,
and precede the target by 300 - 3000ms, there is usually a slowing
of reaction time due to inhibition of return (IOR). Studies of
covert orienting do not consistently find IOR. Many studies that do
not report IOR have used cues that provide predictive information
about target location. To address the inconsistency in the
literature we examined the effect of predictive validity on IOR and
covert orienting performance in general. Undergraduate and
community participants were administered covert orienting tasks in
which cues were either predictive (i.e., valid 80% of the time), or
non-predictive (i.e., 50% valid). When cues provided predictive
information about target location, participants exhibited no IOR.
When cues did not provide predictive information about target
location, IOR was exhibited. It appears the probabilistic
information in predictive cues allowed participants to overcome
IOR, a finding that may explain the inconsistencies in prior
research. The results may also bear on the existence and
interaction of separate attention systems in the brain. Assuming
the so-called "anterior attention system" processes probabilistic
information, the results suggest a role for this system in
modulating the more sensory "posterior attention system" (Posner
and Dehaene, 1994).
|
