DISCRIMINATION OF THE DIRECTION OF MOTION ON THE HUMAN HAND - A PSYCHOPHYSICAL STUDY OF STIMULATION PARAMETERS
DISCRIMINATION OF THE DIRECTION OF MOTION ON THE HUMAN HAND - A PSYCHOPHYSICAL STUDY OF STIMULATION PARAMETERS
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DOI：
10.1152/jn.1994.71.6.2414
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发表时间：
1994-06-01
影响因子：
2.5
通讯作者：
SKLAR, BF
中科院分区：
文献类型：
--
作者：
GARDNER, EP;SKLAR, BF
1.在这些实验中，我们评估的相对重要性的空间和时间属性的移动触觉刺激，在确定人类的能力，以区分其运动方向。通过使用OPTACON刺激器的触觉阵列向皮肤上的相邻位置施加一系列脉冲来模拟沿手指的沿着运动。模拟运动允许我们独立地改变整体移动距离以及连续刺激的间隔、时间和数量。时空参数的不同组合使我们能够进一步研究运动的表观速度和扫描持续时间与行为表现的关系。使用信号检测技术来测量辨别准确度以计算辨别参数d'和PCmax，PCmax是运动方向的正确识别百分比的无偏差测量。在路径长度恒定的实验中，运动方向的可辨别性随着连续脉冲之间的间隔变窄而增加。类似地，对于给定的脉冲间隔，辨别的准确度随着距离线性增加，在完美的性能下饱和。这些对表现的明显空间效应实际上反映了呈现在皮肤上的刺激的总数，而不是它们的接近程度。包含相同数量的脉冲的扫描是同样可辨别的，而不管它们的间隔或在皮肤上交叉的总距离如何。在1.2-、2.4-和4.8-mm间距处获得的d'值在作为扫描中脉冲总数的函数绘制时看起来是不可区分的。实验中，移动的距离和脉冲之间的间隔随机变化证实，歧视的准确性取决于扫描中的脉冲的总数，而不是穿过的路径的空间维度。仅刺激标记皮肤上的开始和停止位置的两个点似乎不足以使受试者正确辨别运动的方向。无论两点相距1.2 mm还是4.8 mm，两点刺激都能增强随机性能。当连续输送八个或更多个脉冲时，可辨别性线性上升至接近完美的性能。d'和PCmax曲线的外推表明，对于75%正确辨别穿过皮肤的运动方向，平均阈值约为3点。刺激间距与固定路径上的可辨别性的关系表明，方向辨别并不简单地涉及计算皮肤上的起始点和终止点的位置或它们的空间差异。相反，数据可以解释的事实，即密集的模式包含更多的刺激，因此传输更多的信息比做更广泛的间隔扫描。5.刺激频率改变了感知的明显运动感觉的性质，但对方向的可辨别性影响不大。以25 Hz施加的脉冲被感觉为不同的轻敲，而在100 Hz时，诱发平滑运动的感觉。脉搏率对方向的可辨别性具有相对弱的影响，其特征在于在50 Hz处的d'比在25或100 Hz处的d'稍高。多变量方差分析表明，刺激速度和扫描持续时间都不是决定运动方向可辨别性的关键因素。
1. In these experiments we assess the relative importance of the spatial and temporal properties of a moving tactile stimulus in determining the ability of humans to discriminate its direction of motion. Movement along the finger was simulated by applying a series of pulses to adjacent locations on the skin using the tactile array of an OPTACON stimulator. Simulated motion permitted us to vary independently the overall distance moved as well as the spacing, timing, and number of sequential stimuli. Different combinations of spatiotemporal parameters allowed us to further examine the relationship of apparent velocity of motion and sweep duration to behavioral performance. Discrimination accuracy was measured using signal detection techniques to calculate the discrimination parameter d' and PCmax, a bias-free measure of the percent correct identification of the direction of motion.2. In experiments where the path length was constant, discriminability of the direction of motion increased as the spacing between successive pulses narrowed. Similarly, for a given interpulse spacing, the accuracy of discrimination increased linearly with distance, saturating at perfect performance. These apparent spatial effects on performance actually reflect the total number of stimuli presented to the skin rather than their proximity. Sweeps containing the same number of pulses are equally discriminable regardless of either their spacing or the total distance crossed on the skin. d' values obtained at 1.2-, 2.4-, and 4.8-mm spacings appear indistinguishable when plotted as a function of the total number of pulses in a sweep.3. Experiments in which both the distance moved and the spacing between pulses was varied randomly confirmed that discrimination accuracy depends on the total number of pulses in a sweep rather than the spatial dimensions of the path traversed. Stimulation of only two points that mark the start and stop locations on the skin appears insufficient to enable subjects to discriminate correctly the direction of motion. Two-point stimulation elicits random performance whether the points lie 1.2 or 4.8 mm apart. Discriminability rises linearly to near-perfect performance when eight or more pulses are delivered sequentially. Extrapolation of the d' and PCmax curves suggests a mean threshold of approximately three points for 75% correct discrimination of the direction of motion across the skin.4. The relationship of stimulus spacing to discriminability over a fixed path suggests that direction discrimination does not simply involve computation of the location of the start and stop points on the skin or their spatial disparity. Rather, the data can be explained by the fact that the denser patterns contain more stimuli and therefore transmit more information than do more widely spaced sweeps.5. The stimulation frequency modifies the nature of the perceived sensation of apparent motion but has little effect on discriminability of direction. Pulses applied at 25 Hz are felt as distinct taps, whereas at 100 Hz a sensation of smooth motion is evoked. The pulse rate has a relatively weak effect on discriminability of direction characterized by a slightly higher d' at 50 Hz than at 25 or 100 Hz. Multivariate analysis of variance indicates that neither the stimulation velocity nor the sweep duration are crucial factors determining discriminability of the direction of motion.