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|Title:||Adaptation to visual displacement through a water-air interface|
|Authors:||O'Reilly, Joseph Patrick|
|Abstract:||Previous research on the accuracy of distance estimation of targets viewed through a water-glass-air interface (such as through a diver's facemask) has been inconsistent with effects predicted from optical principles involved. Emphasis was on the amount and types of adaptation occurring after adjusting for the effects of distortion at close (arm's reach) distances. The recoding of sensory processing systems underlying adaptive performance was investigated with reference to existing prismatic distortion results. Distance estimation was utilized as the dependent measure, with consideration given to the function of oculomotor cues from accommodation and convergence. Reference was made to Festinger's theory of efferent readiness by stressing learning of efferent response sets activated by afferent visual input. The effects of different forms of sensory recoding after prolonged exposure to distorted visual input was investigated, with 18 experienced and 18 novice divers performing eye-hand coordination tasks during an adaptation (warm-up) and an experimental session. During the former period~, 24 minutes underwater, §.S practiced reaching tasks requiring ballistic movement while minimizing visually guided responding. Experimental tasks administered during the last 12 minutes underwater differed on the amount of conflict with the distorted visual input. After-effect measurements were taken in air after 12, 24, 30 and 36 minutes, on reaching responses to targets placed 7 and 14 inches from the §.. Measures of accuracy were supplied by both working and non-working hands. Accuracy of distance estimating while underwater was tested at the end of 0, 12, 24 and 36 minutes of practice in the distorted environment; with §.S matching targets set at 6, 12 and 18 inches. Only working hand responses were collected for the underwater testings. Comparison of working and non-working hand responses on the aftereffect measurements provided an indication of visual vs. proprioceptive adaptation. Results showed that experienced divers adapted with both working and non-working hands. Novice divers exhibited adaptation only with their working hand during the adaptation session, but showed soma evidence of non-working hand adaptation during the experimental phase. Initially, working hand responses did not differ for the two experience groups, while experienced divers demonstrated significantly more adaptation with their non-working hand than did the novices. Experienced divers significantly increased adaptative responding with working and non-working hands over time, while novice performance did not change after the second 12 minute practice session. The results .were taken as evidence of visual adaptation by §,S experienced in performing in the distorted environment, and proprioceptive adaptation for inexperienced §.s. Adaptation over time was apparent from underwater distance estimation results. Increased underestimation from air pretests occurred as the target placement distance increased. Novices exhibited significantly greater loss in accuracy on initial underwater measurements, gradually reaching the level of proficiency of the more experienced divers. Neither group demonstrated perfect adaptation during the 36 minutes of underwater testing for the 12 and 18 inch distances, although adaptation was complete for the closer (6 inch) placement. Interpretations for increased adaptation at closer distances were presented. Rationale were provided to integrate existing reports of distance overestimation with underestimation of distance found in the present investigation, and that predicted by optical principles. Further experiments designed to clariy the controversy between visual and proprioceptive restructuring were suggested.|
Bibliography: leaves 112-121.
ix, 121 l illus
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|Appears in Collections:||Ph.D. - Psychology|
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