SUSTAINED AND TRANSIENT MECHANISMS IN HUMAN-VISION - TEMPORAL AND SPATIAL PROPERTIES
SUSTAINED AND TRANSIENT MECHANISMS IN HUMAN-VISION - TEMPORAL AND SPATIAL PROPERTIES
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DOI：
10.1016/0042-6989(78)90079-2
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发表时间：
1978-01-01
期刊：
影响因子：
1.8
通讯作者：
LEGGE, GE
中科院分区：
文献类型：
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作者：
LEGGE, GE
在两个实验中，从心理物理学角度研究了持续和瞬态机制的特性。首先，测量 6 个正弦光栅的对比度阈值，范围为 0.375-12.0 c/deg [周期/°]，持续时间为 18-3000 ms 的 10 个。在存在和不存在高对比度 20 ms 光栅的情况下测量阈值，该光栅掩盖了信号的起始和偏移。在 1.5 c/deg 及以上，未屏蔽阈值随着持续时间的幂函数分两个阶段下降，达到接近 1000 ms 的渐近水平。低于 1.5 c/deg，未屏蔽阈值变得与超过 100 ms 的持续时间无关。在所有频率下，屏蔽阈值随着持续时间的幂函数下降至 1000 ms 或更长，但 0.375 和 0.75 c/deg 的曲线从未达到未屏蔽渐近水平。在第二个实验中，通过测量作为掩蔽光栅空间频率函数的阈值仰角，获得了范围为 0.375-12.0 c/deg 的正弦波光栅的空间频率带宽。在 3.0、6.0 和 12.0 c/deg 处，带宽函数在信号频率处达到峰值，并显示出中等带宽频率选择性。低于 1.5 c/deg，带宽函数表现出更宽的空间频率调谐，具有更高的幅度，并且峰值掩蔽向高于信号频率的 1.0-1.5 c/deg 附近的频率发生偏移。两个实验的结果都按照持续/瞬态二分法进行了讨论。
In 2 experiments, properties of sustained and transient mechanisms were studied psychophysically. In the first, contrast thresholds were measured for 6 sineware gratings ranging from 0.375-12.0 c/deg [cycles/.degree.] at 10 durations ranging from 18-3000 ms. Thresholds were measured in the presence and absence of high contrast 20 ms gratings which masked the onsets and offsets of the signals. At 1.5 c/deg and above, the unmasked thresholds decreased as power functions of duration in 2 stages, reaching an asymptotic level near 1000 ms. Below 1.5 c/deg, the unmasked threshold became independent of duration beyond 100 ms. At all frequencies, the masked thresholds decreased as power functions of duration to 1000 ms or more, but the curves for 0.375 and 0.75 c/deg never reached the unmasked asymptotic level. In the 2nd experiment, spatial frequency bandwidths were obtained for sinewave gratings ranging from 0.375-12.0 c/deg, by measuring threshold elevation as a function of the spatial frequency of masking gratings. At 3.0, 6.0 and 12.0 c/deg, the bandwidth functions peaked at the signal frequencies and showed medium bandwidth frequency selectivity. Below 1.5 c/deg, the bandwidth functions exhibited broader spatial frequency tuning, were of higher magnitude, and there was a shift in peak masking to frequencies near 1.0-1.5 c/deg which were above the signal frequencies. The results of both experiments were discussed in terms of the sustained/transient dichotomy.