Vigilance
Vigilance is the property of sustaining one's attention while scanning
the environment for the occurrence of events of significance. For
example, scientists may study the behaviors of prey species attempting
to maintain alertness for possible predators. During World War II,
vigilance behavior was studied among radar operators charged with
reporting the presence of "blips" that might represent
approaching enemy aircraft. Several variables were identified that
influenced vigilance, such as length of time spent
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| Dolphin views a "critical" image. |
continuously observing, and the probability of blips appearing on
the screen. We have explored the dolphin's ability to sustain its
attention while watching for the occurrence of key events on a television
screen placed behind an underwater window. The dolphin watches a series
of "clip-art" images appearing rapidly on the television
screen and reports the occurrence of a 'critical' image or images
by pressing a paddle immediately adjacent to the window. The dolphin
must withhold any response noncritical images. As many as 60 images
may flash by successively on the screen, each of 1 second duration
and separated from other images by 0.5 second intervals. The dolphin's
response time to a critical image, is typically less than one second.
The dolphin correctly reports the occurrence of a critical image between
95-100% of the time, and rarely makes a false alarm by pressing the
paddle for
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| Researcher monitors the dolphin's performance
from a remote location. |
a noncritical image. We have also completed a parallel study, using many different sounds rather then visual images. In this case, the dolphin must report the occurrence of critical sounds. The dolphin's performance was equally good, whether reporting on critical visual images or critical sounds. Only humans have been tested in these types vigilance procedures previously. The results for the dolphin were similar to those for humans, in terms of performance levels and susceptibility to various variables. Clearly, the dolphin is able to sustain its attention for protracted periods and can make rapid discriminations among different images and sounds. The findings of excellent performance with visual images gives further support to the development and utility of the dolphin's visual processing system.
Hoffman-Kuhnt, M. (in preparation). Visual and
auditory vigilance in the bottlenosed dolphin. Ph.D. thesis. University
of Berlin and University of Hawaii.
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