Apthorp Deborah, Cass John, Alais David
School of Psychology, University of Sydney, Sydney, Australia.
J Vis. 2010 Aug 1;10(10):11. doi: 10.1167/10.10.11.
We investigated whether the oriented trails of blur left by fast-moving dots (i.e., "motion streaks") effectively mask grating targets. Using a classic overlay masking paradigm, we varied mask contrast and target orientation to reveal underlying tuning. Fast-moving Gaussian blob arrays elevated thresholds for detection of static gratings, both monoptically and dichoptically. Monoptic masking at high mask (i.e., streak) contrasts is tuned for orientation and exhibits a similar bandwidth to masking functions obtained with grating stimuli (∼30 degrees). Dichoptic masking fails to show reliable orientation-tuned masking, but dichoptic masks at very low contrast produce a narrowly tuned facilitation (∼17 degrees). For iso-oriented streak masks and grating targets, we also explored masking as a function of mask contrast. Interestingly, dichoptic masking shows a classic "dipper"-like TVC function, whereas monoptic masking shows no dip and a steeper "handle". There is a very strong unoriented component to the masking, which we attribute to transiently biased temporal frequency masking. Fourier analysis of "motion streak" images shows interesting differences between dichoptic and monoptic functions and the information in the stimulus. Our data add weight to the growing body of evidence that the oriented blur of motion streaks contributes to the processing of fast motion signals.
我们研究了快速移动的点留下的模糊定向轨迹（即“运动条纹”）是否能有效掩盖光栅目标。使用经典的叠加掩蔽范式，我们改变掩蔽对比度和目标方向以揭示潜在的调谐情况。快速移动的高斯斑点阵列提高了单眼和双眼检测静态光栅的阈值。在高掩蔽（即条纹）对比度下的单眼掩蔽对方向有调谐作用，并且展现出与用光栅刺激获得的掩蔽函数相似的带宽（约30度）。双眼掩蔽未显示出可靠的方向调谐掩蔽，但极低对比度下的双眼掩蔽会产生窄调谐的促进作用（约17度）。对于同向条纹掩蔽和光栅目标，我们还探讨了掩蔽作为掩蔽对比度函数的情况。有趣的是，双眼掩蔽呈现出经典的“勺状”TVC函数，而单眼掩蔽则没有凹陷且“柄部”更陡峭。掩蔽存在非常强的无方向成分，我们将其归因于瞬时偏向的时间频率掩蔽。对“运动条纹”图像的傅里叶分析显示了双眼和单眼函数以及刺激中的信息之间的有趣差异。我们的数据进一步支持了越来越多的证据，即运动条纹的定向模糊有助于快速运动信号的处理。
