两种参照作用下的视觉定位

本实验采用多点视觉定位作业,研究视觉定位中的两种参照对定位成绩的影响。实验采用一些附加线条与三个刺激形成有特征的刺激图和无特征的刺激图,并与没有附加线条的情况进行了比较。有特征的刺激图是指这些附加的线条与刺激点构成一定的特征,如一个字母或图形等;无特征的刺激图指刺激点不能与附加线条构成有规律的特征。结果发现,当有附加线条的图形呈现时,被试的定位误差大于控制组,表现出一级参照对视觉定位的干扰作用,而且在呈现时间为100ms、200ms、300ms时,都是如此。在有特征组内,不同的特征对定位精确性的影响依赖于时间因素。     

刺激结构对视觉定位的影响

本实验采用多点定位作业,结合部分报告法,研究视觉刺激的整体结构对定位成绩的影响。所呈现的刺激为1、2、3或4个颜色点。其中2、3、4点刺激分别是直线、正三角形和正方形。结果发现,当呈现时间较长时,1点和2、3、4点的定位误差无显著差异。但是1点的定位反应时却显著少于2、3、4点。这提示出现视觉定位的结构效应。而当呈现时间较短时,却没有这种结构效应。实验还发现,这种结构效应并不因刺激结构的不同而有区别。     

不同框架下的视觉定位

本实验探讨了对置于正方形、等边三角形和圆中的刺激点所进行的１点定位、２点定位、３点定位,并比较了在定位有框架和定位无框架时的情况。结果发现：（１）在刺激呈现时间为１００ｍｓ和３００ｍｓ时．在３种定位任务中,当定位有框架时被试定位的绝对误差均小于定位无框架的。（２）在两种呈现时间下被试在３种定位任务中的绝对误差均处于同一水平,表现出现了视觉定位中的结构效应,并且几个不同的框架没有不同的作用。     

得失情境下他人参照点及心理距离对自我-他人利益权衡的影响

以福利权衡率(WTR)为利他程度的指标, 通过3个实验逐步深入地考察了得失情境下他人参照点及心理距离对自我-他人利益权衡的影响。实验1的结果表明, 得失情境并未改变被试的WTR。实验2引入他人底线、现状和目标三个参照点变量, 发现被试获益情境下的WTR高于损失情境, 且WTR从高到低依次为他人临近底线、目标和现状; 他人临近底线时, 被试在获益情境下的WTR高于损失情境, 而他人临近现状和目标时, 个体在得失情境下的WTR无显著差异。实验3进一步引入心理距离变量, 发现心理距离较近他人的WTR高于较远他人, 且与得失情境和参照点发生了复杂的交互效应, 得失情境的主效应消失了, 但总体上并未改变实验2发现的参照点效应。这些结果对于更深入地理解得失不对称效应、三参照点理论及社会折扣和自我-他人决策差异研究的相关发现具有一定的启示意义。     

正负参照点下性别和损益情景对大学生延迟折扣的影响

大量研究表明,延迟折扣受到个体特质性和状态性因素的影响。本研究通过两个实验分别探究正参照点(实验1)和负参照点(实验2)下,特质性因素性别和状态性因素损益情景对大学生个体延迟折扣的影响。实验1研究发现,在正性参照点下,无论男女,收益情景的主观远期价值远高于损失情景。实验2研究发现,在负性参照点下,男女在损益情景的主观远期价值不同;与男性相比,女性的主观远期价值在损失情景中更高,而在收益情景中则无显著差异。本研究结果表明,在不同的参照点下,男女在损益情景中表现了不同的延迟折扣倾向;与男性相比,女性在负性参照点面对损失情景跨期选择时,更愿意选择延迟赔偿。     

多参照系条件下信息获取方式对绝对方位判断的影响

把参照系整合基础上的绝对方位判断分解成路径获取过程（目标位置信息）、自身定向过程（前行方向信息）和物体定位过程（目标物体相对于参照物体的方位信息）,系统地考察了多参照系条件下信息获取方式对该任务的影响。研究以视觉形式呈现空间信息,实验1a和1b的任务中均包括上述三个过程,前者以地图的形式呈现前行方向信息、后者以语词的形式直接呈现前行方向信息;实验2有两个任务,分别独立于路径描述（定位后判断）和自身定位（定向后判断）。所有任务均为目标位置（R0o－前、R45o－左前/右前、R90o－左/右、R135o－左后/右后, R180o－后）×前行方向（北、东南西、斜方向）的组内设计、因变量为正确率和判断时间为主,共有64名大学生被试（男女各半）参与实验。发现：0o和180o位置优势效应、朝北优势效应在所有任务中都很明显;实验1和定向后判断任务中存在正方向R90o位置优势效实;定位后判断时间短于定向后判断时间,但总体所用时间上没有差异。结合信息获取的方式和可能使用到的判断策略,从绝对方位判断的认知结构上展开了讨论。     

静止与动态定位任务中飞行员视觉空间模板的表征计算

采用静止和动态空间定位任务对飞行员与普通被试进行对照研究,考察参照条件、目标数量、空间性质对空间定位的影响,探索静止和动态视觉空间模板表征建构特征及其个体差异。结果显示：（1）在静止空间,有距离参照定位任务是较易任务而无距离参照任务较难,飞行员的无距离参照任务完成较好;（2）在运动空间,有运动轨迹参照定位任务较易而无轨迹参照任务较难,飞行员两种任务均完成较好,无参照条件使控制组正确率大为下降。（3）两组在双目标任务上的差异比之单目标任务更大,且飞行员表现出双目标协同优势。结论：飞行员视觉空间模板的功能更强,表现为对静止空间形成较为准确距离表征、对运动空间即时建构运动轨迹表征。     

不同记忆提取条件下的自我参照效应

通过操纵记忆提取的条件,本实验比较了自我参照、他人参照和无参照(褒义/贬义)任务下的记忆效果.结果发现:(1)自我参照编码在再认测验中出现了显著的提取优势(F(2.41)=6.097,p<0.01);(2)自我参照编码在颜色一致/不一致判断中未出现显著的提取优势(F(2,41)=1.039,p=0.363);(3)再认测验中,颜色不一致旧词的再认辨别力高于一致条件(F(1,41)=3.139,p=0.084).     

错误记忆的自我参照效应：易化的作用

采用DRM范式,设置三种参照对象条件（自我、他人和中性参照）,考察错误记忆是否存在自我参照效应。结果发现：（1）与正确记忆一样,错误记忆中亦存在自我参照效应;（2）无论是正确记忆还是错误记忆,自我参照条件下的回忆成分均显著多于他人参照和中性参照,但熟悉性成分在三种不同参照对象条件下没有显著差异;（3）当词表中学习项目由分组呈现变为随机呈现时,错误记忆的自我参照效应仍稳定存在。结果揭示,自我参照效在促进正确记忆的同时,亦可易化错误记忆效应。     

音乐情境中自我参照加工的时间特征：来自ERPs的证据

采用事件相关电位技术, 考察在有情境条件下不同层面的自我参照加工的特性及其神经机制。实验发现,在两种音乐情境条件下个体自我参展刺激所激发的P300波幅比集体自我参照刺激和非自我刺激更大,而集体自我参照刺激所激发的P300波幅比非自我刺激更大;两种音乐情境条件下个体自我参照刺激所激发的P300波幅差异显著,而集体自我参照刺激所激发的P300波幅差异不显著。研究结果表明了在不同的情境中,个体自我参照加工的差异较大,表现出不稳定的特征;个体自我参照加工与集体自我参照加工的神经机制是不同的。这些结果还可能表明了相对于集体自我来讲,个体自我是自我的核心层面。     

附加点作用下两点距离的触觉辨别

在被动触觉的距离知觉实验中,被试的右手保持不动,将各种三点型式的刺激轻轻接触食指腹侧或以一定速度通过其表面,要求被试判定外侧两点的直线距离并在一根量尺上复现出来．结果发现：（１）当刺激快速通过皮肤表面时,外侧两点距离表现出低估,其知觉距离显著地小于刺激静止或慢速运动条件下的知觉距离;（２）当中间附加点偏离外侧两点间想象连线较大时,外侧两点的知觉距离显著地小于中间附加点偏离较小时的知觉距离,偏离较大的中间附加点似乎将外侧两点拉近了,缩短了其知觉距离,出现知觉亲和现象．这种现象与刺激是否运动无关．     

Mobility of normal observers under conditions of reduced visual input.

The importance in mobility performance of the rate of presentation of visual information, binocular versus monocular vision, the use of multiple rather than single reference points, and local motion parallax was investigated in two experiments. In each experiment ten subjects walked a triangular mobility course in a totally darkened room; the only visible targets were light emitting diodes (LEDs), mounted on poles, at the apices of the triangle. The LEDs were mounted so that one or two could be used in a trial; if two were used the distance between them was varied horizontally (in experiment 1) and vertically (in experiment 2). The subjects walked around the course under a range of conditions, including two 'optimal trials' in full light. The LEDs were flashed for 1 ms at frequencies of 0.5, 1 and 5 Hz in experiment 1 and at 1 and 5 Hz in experiment 2. Mobility was measured with the use of an ultrasonic locator system which measured the subject's position on the course 10 times per second. The mean velocity of the subject in traversing the course was significantly reduced when the flash rate was slower, when the subject had one eye occluded, or when there was only one LED on the pole; when the spacing between the LEDs was varied, either vertically or horizontally performance was unaffected. These results imply that the frequency of updating of visual information is important in determining mobility performance, as are binocular cues, but that local motion parallax is not important. The number of LEDs on each pole had a significant effect on mobility performance an 'object' (two lights) gave more information than a point reference.     

Testing the reference-dependent model: an experiment on asymmetrically dominated reference points

Standard choice theory assumes choice to be independent of the point of reference. Based on a number of studies which challenge this assumption, Tversky and Kahneman have proposed a reference-dependent model which captures the influence of reference points on individual choice. If choice is reference-dependent, switching the reference point so that it is first dominated by x and then by y increases the likelihood of choosing y. Switching the location of an asymmetrically dominated reference point without altering the dominance relationship should also influence reference-dependent choice in a predicted manner. In this paper the reference-dependent model is tested in two experiments which focus on asymmetrically dominated reference points. The results of these experiments give further confirmation to the reference-dependent model. © 1998 John Wiley & Sons, Ltd.     

Finger width corrections in Fitts' law: implications for speed-accuracy research

This note points out that using the finger as a test probe in a Fitts task may lead to misleading results, because of the increased target tolerance resulting from the width of the finger pad. An experiment demonstrates the need to use a corrected target width when calculating the index of difficulty; without this correction, information processing rates are overestimated. An example is given of a developmental study in which the finger pad size changes with age. The resulting changes in the calculated rates of information processing are shown to be markedly different for the different age groups.     

Studies on sensory feedback: III the effects of display gain on tracking performance

Instrumentation is described which permits study of the effects of different forms of visual feedback display on the patterns of fine movement obtained from the extended human index finger when the subject is attempting to keep his finger at a fixed point in space. The task is a compensatory tracking task in which the only source of input to the system is the subject's own finger movement. The effects of increasing the gain (or amplification) of a proportional error signal on the pattern of finger movement was studied. Gains of 1, 2, 4, 10, 20 and 40 were studied with a group of 24 subjects. Increasing the gain of a proportional error signal resulted in a marked improvement in the ability of subjects to maintain their extended finger at a fixed point in space. As the gain of the error signal was increased, the subject's high-amplitude, low frequency errors were reduced, and there was a progressive appearance of high-frequency activity of low-amplitude, more accurately centred about the reference position in space. A total off-target area measure (integrated absolute error) showed marked decrease in scores as the amplification of the error signal was increased from 1 through 10. Beyond this gain there was no appreciable additional improvement in motor control, however no degradation of control was noted to characterize the group performance.

Exploratory studies were undertaken to permit comparison of the effects of increasing the gain of a proportional visual display with the effects of increasing the gain of non-proportional visual and auditory displays. An increase in the dominant-energy frequency was noted as the error signal gain was increased, independent of whether a proportional visual, or non-proportional visual or auditory display was used. This observation suggests that common mechanisms mediate the processing of the gain parameters of feedback displays, in some measure independent of the display form or the sensory modality used for presentation.     

Perceived localizations and eye movements with action‐generated and computer‐generated vanishing points of moving stimuli

When observers localize the vanishing point of a moving target, localizations are reliably displaced beyond the final position, in the direction the stimulus was travelling just prior to its offset. We examined modulations of this phenomenon through eye movements and action control over the vanishing point. In Experiment 1 with pursuit eye movements, localization errors were in movement direction, but less pronounced when the vanishing point was self‐determined by a key press of the observer. In contrast, in Experiment 2 with fixation instruction, localization errors were opposite movement direction and independent from action control. This pattern of results points at the role of eye movements, which were gathered in Experiment 3. That experiment showed that the eyes lagged behind the target at the point in time, when it vanished from the screen, but that the eyes continued to drift on the targets' virtual trajectory. It is suggested that the perceived target position resulted from the spatial lag of the eyes and of the persisting retinal image during the drift.     

The effects of response stimuli interval on error priming in sequential object naming

Two experiments are reported, which examine the effect of altering response stimulus interval on the positive and negative error priming effects found during sequential object naming. Positive error priming refers to errors that relate to earlier responses at above chance rates. Negative error priming refers to the absence of errors that refer to the immediately preceding trial in particular (Lag 1), and this has been interpreted as a brief inhibitory effect. In Experiment 1, a series of pictures of animals were presented, with either 4 or 8sec intervening between response and next stimulus (RSI). Positive and negative error priming was evident in both conditions, though the positive error priming appeared to be attributable to only a subsection of the participants. Errors began to emerge at shorter lags in the 8sec RSI condition than the 4sec RSI condition, and this is inconsistent with any account which suggests inhibition is released after the next trial. In Experiment 2, the RSIs between related animal pictures were just over 8 and 16sec, and an intervening unrelated item was included between related pictures. Lag 1 errors were now the most frequent response in the long RSI condition, and there was an increase in the incidence of Lag 1 errors across RSI conditions. A preliminary assessment of the effects of adding an unrelated item suggested that it may cause a partial release from inhibition. Taken together, the data are consistent with the theory that inhibition decays over time, and the results are discussed with reference to other inhibitory effects in cognition.     

Interaction of Tremor and Magnification in a Motor Performance Task With Visual Feedback

In this study, the interaction between increased gain in the visual feedback loop and motor control of the periphery was investigated. Participants (N = 15) were asked to maintain a constant finger position while they used magnified visual feedback. The measure of the accuracy of each trial was the standard deviation (trial error) of the finger position. Trials performed under magnification had lower trial errors than trials without magnification. The change in trial error between trials with and without magnification proved greater than the difference between trials at any 2 magnifications. In contrast, the differences between individual subjects were often greater than the differences between performances at individual magnifications. At higher magnifications, performance seemed to be limited by the tremor; the ratio of trial error to tremor intensity was constant. When applied to microsurgery, the present results accord with those found in earlier research, including investigations that have found that the level of magnification used in microsurgery is not the most significant factor in achieving good results and that tremor is the limiting factor in microsurgical tasks.     

Sensitivity to shifts of a point stimulus: An instance of tactile hyperacuity

The sensitivity of the tactile sense to shifts in the position of a point stimulus was determined at four body loci: the index finger, forehead, belly, and back. Water-jet stimulation was used, a method which allows frictionless travel of a point stimulus over the skin. Three subjects were tested by means of the method of forced choice, with the task being to say whether the stimulus moved to the right or to the left. The shift threshold was defined as that shift excursion which gave rise to 75% correct responding. The basic finding was that shift thresholds were on the order of 10 to 30 times smaller than the corresponding two-point limens obtained by Weinstein (1968) for the same body loci. These unexpectedly small shift thresholds indicate an exquisite sensitivity of the cutaneous sense to rapid changes in position of a point stimulus. A physiological model is presented which accounts for the difference between localization and spatial resolution. nt]mis|This research was supported by Department of Health~ Education, and Welfare Grant 14-P-SS282/9 from the Social and Rehabilitation Services, NIH Research Grant R01-EY-00686 from the National Eye Institute, and the Smith-Kettlewell Eye Research Foundation.