Huang Pi-Chun, Maehara Goro, May Keith A, Hess Robert F
McGill Vision Research, Department of Ophthalmology, Montreal, Quebec, Canada.
J Vis. 2012 Feb 16;12(2):14. doi: 10.1167/12.2.14.
To assess the effects of spatial frequency and phase alignment of mask components in pattern masking, target threshold vs. mask contrast (TvC) functions for a sine-wave grating (S) target were measured for five types of mask: a sine-wave grating (S), a square-wave grating (Q), a missing fundamental square-wave grating (M), harmonic complexes consisting of phase-scrambled harmonics of a square wave (Qp), and harmonic complexes consisting of phase-scrambled harmonics of a missing fundamental square wave (Mp). Target and masks had the same fundamental frequency (0.46 cpd) and the target was added in phase with the fundamental frequency component of the mask. Under monocular viewing conditions, the strength of masking depends on phase relationships among mask spatial frequencies far removed from that of the target, at least 3 times the target frequency, only when there are common target and mask spatial frequencies. Under dichoptic viewing conditions, S and Q masks produced similar masking to each other and the phase-scrambled masks (Qp and Mp) produced less masking. The results suggest that pattern masking is spatial frequency broadband in nature and sensitive to the phase alignments of spatial components.
为评估图案掩蔽中掩蔽成分的空间频率和相位对齐的影响，针对五种类型的掩蔽，测量了正弦波光栅（S）目标的目标阈值与掩蔽对比度（TvC）函数：正弦波光栅（S）、方波光栅（Q）、缺基方波光栅（M）、由方波相位打乱的谐波组成的谐波复合体（Qp）以及由缺基方波相位打乱的谐波组成的谐波复合体（Mp）。目标和掩蔽具有相同的基频（0.46周/度），且目标与掩蔽的基频成分同相添加。在单眼观察条件下，只有当目标和掩蔽存在共同的空间频率时，掩蔽强度才取决于与目标空间频率相差甚远（至少为目标频率的3倍）的掩蔽空间频率之间的相位关系。在双眼分视条件下，S和Q掩蔽产生的掩蔽彼此相似，而相位打乱的掩蔽（Qp和Mp）产生的掩蔽较少。结果表明，图案掩蔽本质上是空间频率宽带的，并且对空间成分的相位对齐敏感。
