明眼者與盲者對器物可伸取性的知覺與姿勢控制

Perception of Object Reachability and Postural Control in Sighted and Blind People

在無視覺情境下，個體可透過聽覺判斷器物之可伸取性。當面對不同的工作要求或環境，藉身體擺動的調整得以擷取有效訊息。而盲者的主要知覺系統及經驗與明眼者不同。本研究目的即在檢證明眼者與盲者對器物可伸取性的知覺差異，並透過身體擺動，檢視兩者覺知環境賦使時的姿勢控制。實驗參與者為20名明眼者及8名全盲者。實驗中明眼組以視覺或聽覺，判斷是否可伸手拿取前方器物，並評估判斷信心。盲組則以聽覺判斷。覺知目標物同時記錄參與者的身體擺動。由實驗結果歸納以下結論：(1)明眼者與盲者以聽覺判斷目標物的可伸取性方面，兩者有相同的準確性和身體尺度比例，但盲者有較大身體擺動；(2)比較無判斷與判斷試作時的身體擺動，明眼者以視與聽覺判斷時，皆會減少身體擺動，而盲者則在聽覺判斷時增加身體擺動；(3)明眼者視、聽覺判斷部分，最大可伸取距離的準確性相同，視覺判斷有較大身體尺度比例，較小的身體擺動。因此，為了覺知環境賦使，盲者與明眼者皆產生行動因應的改變，符合生態心理學的知覺－－行動配連。盲者與明眼者視、聽知覺經驗不同，因而發展出不同的姿勢控制方式，以獲得適配的環境賦使知覺。

Individuals can judge the reachability of object by hearing without vision. Body sway modulation is to pick up available information while facing various task demands or different environments. The primary perceptual system and experiences of blind people are different from those of sighted people. The purposes of this study were to investigate the difference in perception of reachability for sighted and blind people, and to observe their body sway so as to examine postural control while perceiving affordances. Twenty sighted and 8 totally blind people served as participants. The sighted group visually and audibly judged whether the object in front of them was reachable, and rated the confidence of their judgment. The blind group judged the reachability audibly only. Body sway measures were recorded when participants perceived the target. Based on the results, the conclusions are as follows: (1) Regarding sighted and blind people's auditory judgment of reachability, the two groups exhibited equal accuracy and body-scaled ratio, but higher body sway was found in blind people; (2) Comparing between non-judgment and judgment trials, the body sway of sighted people reduced in visual and auditory judgment, but the body sway of blind people increased in auditory judgment; (3) Visual and auditory judgments of sighted people showed equal accuracy in perception of maximum reachable distance, but higher body-scaled ratio and lower body sway for visual judgment were found. Therefore, consistent with perception-action coupling in ecological psychology, both blind and sighted people's actions would change in order to perceive affordance. Sighted and blind people with different experiences in visual and auditory perception have developed dissimilar patterns of postural control to perceive the fitting affordance perception.