Gentilucci M, Benuzzi F, Bertolani L, Gangitano M
Istituto di Fisiologia Umana, Università di Parma, Via Volturno 39, 43100 Parma, Italy.
Exp Brain Res. 2001 Mar;137(1):36-44. doi: 10.1007/s002210000639.
This kinematic study aimed to determine whether color is a stimulus property involved in the control of reaching-grasping movements. Subjects reached and grasped a target-object, located either on the right or on the left of the subject's midline. A distractor, placed along the subject's midline, could be randomly presented. The colors, i.e., both chromaticity (red and green stimuli were presented) and lightness, of the target and distractor were varied in experiment 1. Only stimulus lightness and only stimulus chromaticity were varied in experiments 2 and 3, respectively. In experiment 4 subjects matched with their thumb and index finger the size of the target-stimuli presented in experiment 1. Chromaticity (experiments 1 and 3) of the target and distractor influenced grasp, but not reach. Maximal finger aperture was larger during grasping the red than the green target. Data collected in the matching task (experiment 4) confirmed a trend to overestimate the red target and to underestimate the green one. During grasp, hand shaping was influenced by distractor chromaticity when it was different from target chromaticity. Distractor lightness affected reach, but not grasp (experiments 1 and 2). Reach was slower when the distractor was lighter and arm trajectory veered away from it. The results of the present study suggest that color, that is the ensemble of chromaticity and lightness, is a stimulus property involved in the control of reaching-grasping. The different effects of target color on reach and grasp support the notion that intrinsic object properties, such as color, affect grasp more than reach. In addition, the different effects of distractor chromaticity and lightness on reach and grasp confirm that target-objects are visually extracted from surrounding cues by means of different processes, according to the required motor response.
这项运动学研究旨在确定颜色是否是参与控制伸手抓握动作的一种刺激属性。受试者伸手去抓位于其身体中线右侧或左侧的目标物体。可以随机呈现一个沿着受试者中线放置的干扰物。在实验1中,目标物和干扰物的颜色,即色度(呈现红色和绿色刺激)和明度都有所变化。在实验2和实验3中,分别只改变刺激明度和只改变刺激色度。在实验4中,受试者用拇指和食指匹配实验1中呈现的目标刺激的大小。目标物和干扰物的色度(实验1和实验3)影响抓握,但不影响伸手动作。抓握红色目标时的最大手指开度比抓握绿色目标时更大。在匹配任务(实验4)中收集的数据证实了高估红色目标和低估绿色目标的趋势。在抓握过程中,当干扰物的色度与目标物的色度不同时,手部形状会受到干扰物色度的影响。干扰物的明度影响伸手动作,但不影响抓握(实验1和实验2)。当干扰物较亮时,伸手动作会变慢,手臂轨迹会偏离它。本研究结果表明,颜色,即色度和明度的总和,是参与控制伸手抓握动作的一种刺激属性。目标颜色对伸手和抓握的不同影响支持了这样一种观点,即诸如颜色等物体固有属性对抓握的影响大于对伸手的影响。此外,干扰物色度和明度对伸手和抓握的不同影响证实,根据所需的运动反应,目标物体是通过不同的过程从周围线索中视觉提取出来的。