Dorais A, Sagi D
Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Vision Res. 1997 Jul;37(13):1725-33. doi: 10.1016/s0042-6989(96)00329-x.
Contrast detection thresholds are known to increase with background contrast, a phenomenon called contrast masking. We found that, under some conditions, observers improved their masked detection performance by repetitive practice of a masking experiment. This learning effect resulted in a cancellation of suprathreshold contrast masking within the contrast range measured. A two-alternative forced-choice discrimination paradigm was used, with stimuli consisting of Gabor signals as maskers and target, presented at the same location and time. Untrained observers showed increased detection thresholds with increasing mask contrast for suprathreshold mask contrasts, but perceptual learning caused an elimination of this classical effect, with masked thresholds reaching the no-mask level and below. Learning did not decrease, but rather somewhat increased, discrimination thresholds when target and mask shared the same Gabor signal parameters. Performance improvement was found to be specific for orientation and mask configurations, though it did transfer between mirror symmetric mask configurations and between eyes. These results argue against a static transducer function-based account for contrast masking and are consistent with a theory assuming multiple feature-based interactive network capable of long-term gain modifications.
已知对比度检测阈值会随着背景对比度的增加而提高，这种现象称为对比度掩蔽。我们发现，在某些条件下，观察者通过重复进行掩蔽实验来提高其被掩蔽的检测性能。这种学习效应导致在测量的对比度范围内超阈值对比度掩蔽被消除。使用了二选一强制选择辨别范式，刺激由作为掩蔽物和目标的Gabor信号组成，在相同位置和时间呈现。未经训练的观察者在超阈值掩蔽对比度下，随着掩蔽对比度的增加，检测阈值升高，但感知学习消除了这种经典效应，被掩蔽的阈值达到无掩蔽水平及以下。当目标和掩蔽物共享相同的Gabor信号参数时，学习并没有降低，反而在一定程度上提高了辨别阈值。发现性能提升对于方向和掩蔽配置是特定的，尽管它确实在镜像对称掩蔽配置之间以及眼睛之间转移。这些结果反对基于静态换能器功能的对比度掩蔽解释，并且与假设能够进行长期增益修改的基于多个特征的交互网络的理论一致。
