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document
Hitting the target : relatively easy , yet absolutely difficult . It is generally agreed that absolute-direction judgments require information about eye position , whereas relative-direction judgments do not . The source of this eye-position information , particularly during monocular viewing , is a matter of debate . It may be either binocular eye position , or the position of the viewing-eye only , that is crucial . Using more ecologically valid stimulus situations than the traditional LED in the dark , we performed two experiments . In experiment 1 , observers threw darts at targets that were fixated either monocularly or binocularly . In experiment 2 , observers aimed a laser gun at targets while fixating either the rear or the front gunsight monocularly , or the target either monocularly or binocularly . We measured the accuracy and precision of the observers ' absolute- and relative-direction judgments . We found that ( a ) relative-direction judgments were precise and independent of phoria , and ( b ) monocular absolute-direction judgments were inaccurate , and the magnitude of the inaccuracy was predictable from the magnitude of phoria . These results confirm that relative-direction judgments do not require information about eye position . Moreover , they show that binocular eye-position information is crucial when judging the absolute direction of both monocular and binocular targets .
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Intervention_Other
observers threw darts at targets that were fixated either monocularly or binocularly
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Intervention_Other
observers aimed a laser gun at targets while fixating either the rear or the front gunsight monocularly , or the target either monocularly or binocularly
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Outcome_Mental
accuracy
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Outcome_Other
and
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Outcome_Mental
precision
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Outcome_Other
inaccurate
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Outcome_Mental
inaccuracy
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Participant_Condition
absolute-direction judgments
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Participant_Condition
observers threw darts at targets that were fixated either monocularly or binocularly .
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Participant_Condition
monocularly or binocularly