動作距離與準確度對加減速軌跡影響

Abstract

在費茲定律的典範下，動作距離與目標準確的容忍度被視為是影響動作時間的主要因素；衝量變異模型則直接探討更大的施力造成速度提升而增加終點變異。對稱性衝量變異模式預測間斷性快速瞄準動作有對稱之加、減速衝量，但當目標準確要求提高時，減速的時間比例會增加。本研究以14種不同動作距離與目標大小的組合建構四個費茲難度指數，以完整觀察動作距離與目標大小對加、減速度軌跡比例的影響。方法：參與者為20名右手為慣用手的健康成年人，利用手寫顯示板及壓力感應筆進行費茲工作，完成操弄動作距離及目標寬度的14個情境，每個情境各 20 次成功試作。以二因子重複量數變異數分析檢驗操弄間及難度指數對動作時間、速度峰值、加速度時間比例、加速度距離比例、加、減速度時間、加、減速度距離的影響。另以單一樣本t檢定檢驗速度峰值時間及距離比例與0.5的差異。結果：動作時間隨著難度指數增加而增加；目標寬度減小速度峰值下降，且加速度時間比例增加及加速度距離比例降低；動作距離增加速度峰值增加，且加速度時間比例及加速度距離比例不變。結論：操弄目標寬度或動作距離均可提升難度指數及增加動作時間，但兩者對加速度時間及距離比例有不同的影響。

Under the paradigm of Fitts’ law, the distance of movement and the tolerance of target accuracy are considered the main factors affecting movement time. However, the focus on the increased force that leads to an increased velocity, resulting in greater endpoint variability, was not proposed until the development of the impulse variability model. The symmetrical impulse variability model predicts that the discrete rapid aiming movements have symmetrical acceleration and deceleration impulses, and when the target accuracy requirements increase, the proportion of deceleration time will increase. This study manipulated 14 combinations of different movement distances and target sizes to construct four indices of difficulties to fully observe the effect of distance and target size on the proportion of acceleration and deceleration trajectory. Methods: Twenty right-handed healthy adults performed the Fitts’ tasks, completing 14 conditions that manipulated movement distance and target width, with each condition being tested for 20 successful trials. The two-factor repeated measures ANOVA was used to examine the effects of manipulation and the ID on the movement times, peak velocities, acceleration time rates, acceleration distance rates, acceleration/deceleration times, and acceleration/deceleration distances. Additionally, a one-sample t-test was used to compare the time/location of the peak velocity to the time/distance traveled with 0.5. Results: The movement times increased with the IDs; the peak velocity decreased with decreasing target width, but the acceleration time rates increased, and acceleration distance rates decreased. The peak velocity increased over the increasing distances, but the acceleration time and distance rates remained unchanged. Conclusion: Manipulating target width or movement distance may increase the index of difficulty and movement time, but they have different effects on the rates of acceleration time and distance of the discrete aiming movement.