不确定性和预期有效性对运动方向感知决策的影响

The influence of uncertainty and validity of expectation on the perceptual decision of motion direction

环境中的运动刺激往往多变,更好的方向感知需要同时依赖当前信息和先验信息。然而,当前刺激的不确定性与先验线索的预期有效性在运动方向感知决策中如何整合尚不清楚。研究采用随机点运动范式,要求被试判断散点群的整体运动方向,方向一致的散点为相干点,其比例越低,不确定性越高。实验1比较了不同相干点比例下的感知准确度。根据实验1的结果,选出20%和60%的相干点比例分别对应实验2中散点群的高、低不确定性水平。实验2比较了高、低不确定性和高、低预期有效性(线索正确预测目标的概率)下的感知准确度。结果发现,随着不确定性的降低和预期有效性的增加,感知准确度显著提高;预期效应(高、低有效性下感知准确度的差异)随不确定性的提高而增加。结果表明,先验信息与感觉信息能在运动方向感知决策中整合。研究为双重控制机制(DMC)理论下主动性与反应性控制协同工作的观点提供了实证支持,并为交通事故的解释与预防提供了理论依据。

Accurate perception of motion direction depends on current and prior information. However, it is not clear how the uncertainty of the current stimulus and the validity of expectation from prior information can be integrated into the decision-making for the directional perception. In our experiment, the validity of expectation from a cue, which appears before the stimulus, belongs to the proactive control system, while the uncertainty of stimulus, which changes by the signal-to-noise ratio, belongs to the reactive control system. It is unclear whether the proactive and reactive control systems engage in standard processing or work independently.In order to verify the integrated mechanism of the uncertainty of current sensory information and the validity of expectation from prior cue information on the perceptual decision of motion direction, two experiments were conducted. Experiment 1 employed random dot motion patterns(RDPs) to investigate the appropriate high and low uncertainty conditions. Participants should distinguish the moving direction of coherent dots(in the same direction) while noise dots move in a random direction. The PR(perceptual accuracy) values were compared for various ratios of coherent dots(100%, 80%, 70%, 60%, 20%, 0%). The results indicated that the PR of 60% ratio was significantly lower than that of 100%, while the PR of 20% ratio was significantly different from that of 0%and 60%. Consequently, 20% and 60% ratios can be considered as high and low uncertainty conditions in Experiment 2, respectively.Experiment 2 employed a task combined of associated learning and RDPs paradigm, in which a cue with high(90% correct) or low(10% correct) validity of expectation appeared before moving dots. Results showed that the PR of high uncertainty was significantly lower than that of low uncertainty and reflected a significant increase in PR with a valid cue, demonstrating an expectation effect. Moreover, there was considerable interaction between validity and uncertainty, while the expectation effect was found in both uncertainty conditions.However, the magnitude of expectation effect was lower in low uncertainty than in high uncertainty conditions,suggesting that uncertainty and validity can be influenced in standard cognitive processing.In summary, based on the present results, the prior and sensory information can be integrated into motion perception decision-making. The results can support the cooperation mechanism of proactive and reactive control systems and provide a theoretical basis to prevent traffic accidents. Investigating the effects of uncertainty and validity on the perceptual decision of motion direction of specific individuals(such as veteran or aged drivers)can be considered a future research topic.