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Abstract:
Abstract: Three experiments were designed to assess whether
baboons perceive, as complete, visual forms partially occluded by
other forms. In the first experiment, eight adult baboons were
tested in a computerized task involving a go-NOGO procedure.
Animals were initially trained to criterion to detect a target
(i.e., blue circle) within a display containing two non-overlapping
elemental figures. In the transfer trials of the test sessions, the
target was either partially occluded by, or placed above the other
elemental figure. Results indicated identical response biases in
these two conditions, suggesting that the occluded target was
processed as the entirely visible one. In Experiment 2, an
amputated target similar to the visible part of the occluded target
was presented in transfer trials, in order to verify if the visible
part of the occluded target could control responses behaviors.
Baboons responded to the amputated target as they did to the
entirely visible target. In Experiment 3, the baboons were trained
to discriminate a circle from an amputated circle. Transfer was
then assessed using compound figures either made of the circle
partially occluded by another shape, or made of the amputated
circle spatially separated from another shape. These two displays
elicited identical response biases. These results taken together
suggest that the baboons failed to experience amodal completion in
these three experiments.
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