本研究目的在討個體能否覺知環境－人－人系統穿越間隙的可能性、以及肩寬因素對該可能性的影響。以9名肩寬、肩窄知覺者與9名肩、肩窄伴隨者為實驗參加者。知覺者與伴隨者站立於距離可開關之間隙前3公尺處，知覺者指示研究者調整間隙大小，直至決定知覺者＋伴隨者所組成的環境－人－人系統可穿越的最小間隙寬度為止。之後，知覺者＋伴隨者實際穿越以決定環境－人－人系統最小可穿越間隙寬度。結果顯示，以外在尺度為量尺時，無論伴隨肩寬者或肩窄者，知覺最小寬度與實際最小寬度有顯著差異；知覺最小寬度與實際最小寬度有顯著相關。若依內在尺度為量尺，以間隙寬度除以知覺者＋伴隨者的肩寬為依變項時，無論在知覺或實際環境－人－人系統的穿越間隙能力，伴隨者肩寬、知覺者肩寬因子皆無顯著差異，顯示知覺者係以內在尺度為量尺判斷系統穿越間隙的環境賦使。本研究結論認為個體能以自我本身加上伴隨者的身體屬性為尺度判斷環境－人－人系統的能力。

The study was aimed to investigate the perception of individual's affordances for aperture passage in an environment-person-person system, and the influence of the shoulder width on aperture passage. Nine wide-shoulder and 9 narrow-shoulder undergraduates served as perceivers while another 9 wide-shoulder and 9 narrow-shoulder undergraduates served as companions. Perceivers and companions stood side by side as a dyad and then the perceivers were required to make judgments about the dyads' minimal passable aperture width. The dyads then walked side by side toward the aperture to determine the minimal passed aperture width of the system. The results indicated that despite the shoulder widths of the companions, the perceived minimal aperture width correlated with but different from the actual minimal aperture width. When the ratio between aperture width and the shoulder width of the perceiver + companion was taken into consideration, the ANOVA indicated that the differences between shoulder widths disappeared in both the perceived and actual passed conditions. The perception of the perceivers' affordances for aperture passage for the environment-person-person system was based on the shoulder widths of the perceiver and companion. Individuals were able to perceive affordances for an environment-person-person system based the body-scaled information of a dyad.