Ester Edward F, Klee Daniel, Awh Edward
Department of Psychology, University of California-San Diego.
Department of Psychology, University of Oregon.
J Exp Psychol Hum Percept Perform. 2014 Jun;40(3):1022-33. doi: 10.1037/a0035377. Epub 2013 Dec 23.
Visual perception is dramatically impaired when a peripheral target is embedded within clutter, a phenomenon known as visual crowding. Despite decades of study, the mechanisms underlying crowding remain a matter of debate. Feature pooling models assert that crowding results from a compulsory pooling (e.g., averaging) of target and distractor features. This view has been extraordinarily influential in recent years, so much so that crowding is typically regarded as synonymous with pooling. However, many demonstrations of feature pooling can also be accommodated by a probabilistic substitution model where observers occasionally report a distractor as the target. Here, we directly compared pooling and substitution using an analytical approach sensitive to both alternatives. In four experiments, we asked observers to report the precise orientation of a target stimulus flanked by two irrelevant distractors. In all cases, the observed data were well described by a quantitative model that assumes probabilistic substitution, and poorly described by a quantitative model that assumes that targets and distractors are averaged. These results challenge the widely held assumption that crowding can be wholly explained by compulsory pooling.
当外周目标嵌入杂乱环境中时，视觉感知会显著受损，这种现象被称为视觉拥挤。尽管经过了数十年的研究，但拥挤现象背后的机制仍然存在争议。特征合并模型认为，拥挤是目标和干扰物特征强制合并（例如平均）的结果。近年来，这种观点极具影响力，以至于拥挤通常被视为合并的同义词。然而，许多特征合并的例证也可以用概率替代模型来解释，即观察者偶尔会将干扰物报告为目标。在这里，我们使用对两种可能性都敏感的分析方法，直接比较了合并和替代。在四个实验中，我们要求观察者报告两侧有两个无关干扰物的目标刺激的精确方向。在所有情况下，观察到的数据都能很好地用假设概率替代的定量模型来描述，而用假设目标和干扰物被平均的定量模型来描述则很差。这些结果挑战了一个广泛持有的假设，即拥挤可以完全由强制合并来解释。
