Scott-Brown K C, Orbach H S
Department of Vision Sciences, Glasgow Caledonian University, UK.
Proc Biol Sci. 1998 Nov 22;265(1411):2159-66. doi: 10.1098/rspb.1998.0553.
Change blindness--our inability to detect large changes in natural scenes when saccades, blinks and other transients interrupt visual input--seems to contradict psychophysical evidence for our exquisite sensitivity to contrast changes. Can the type of effects described as 'change blindness' be observed with simple, multi-element stimuli, amenable to psychophysical analysis? Such stimuli, composed of five mixed contrast elements, elicited a striking increase in contrast increment thresholds compared to those for an isolated element. Cue presentation prior to the stimulus substantially reduced thresholds, as for change blindness with natural scenes. On one hand, explanations for change blindness based on abstract and sketchy representations in short-term visual memory seem inappropriate for this low-level image property of contrast where there is ample evidence for exquisite performance on memory tasks. On the other hand, the highly increased thresholds for mixed contrast elements, and the decreased thresholds when a cue is present, argue against any simple early attentional or sensory explanation for change blindness. Thus, psychophysical results for very simple patterns cannot straightforwardly predict results even for the slightly more complicated patterns studied here.
变化盲视——当扫视、眨眼和其他瞬态中断视觉输入时，我们无法察觉自然场景中的大幅变化——似乎与我们对对比度变化高度敏感的心理物理学证据相矛盾。对于简单的、适合心理物理学分析的多元素刺激，能否观察到被描述为“变化盲视”的这类效应呢？由五个混合对比度元素组成的此类刺激，与单个元素相比，引发了对比度增量阈值的显著增加。刺激呈现之前的提示显著降低了阈值，这与自然场景中的变化盲视情况相同。一方面，基于短期视觉记忆中的抽象且粗略表征对变化盲视的解释，似乎不适用于对比度这种低层次图像属性，因为有充分证据表明在记忆任务中表现出色。另一方面，混合对比度元素的阈值大幅增加，以及提示出现时阈值降低，这与任何关于变化盲视的简单早期注意力或感官解释相悖。因此，即使对于这里研究的稍微复杂一些的模式，非常简单模式的心理物理学结果也不能直接预测其结果。
