Sato Kazuki, Kanazawa So, Yamaguchi Masami K
Department of Psychology, Chuo University, 742-1, Higashinakano, Hachioji, Tokyo, 192-0393, Japan.
Japan Society for the Promotion of Sciences, Chiyoda, Tokyo, 102-8471, Japan.
Atten Percept Psychophys. 2016 Jul;78(5):1453-9. doi: 10.3758/s13414-016-1114-7.
Shadows are powerful cues in the perception of shapes. We can perceive shading and cast shadow implicitly. We investigated infants' ability to detect a single discrepant figure that was depicted by shading or cast shadow and examined the influence of the contrast polarity of shadows on this process. In Experiment 1, we manipulated the blur direction of a shadow to create stimuli that appeared either to be partially shaded or to cast a shadow and then used a preference to test whether this difference would allow 5- to 8-month-old infants to discriminate the figures that adults were able to perceive as different shapes. Only 7- to-8-month-old infants could differentiate one shading figure from cast shadow figures, and vice versa. In Experiment 2, we reversed the contrast polarity of the figure (dark object with a light shadow) and tested whether discrimination was affected. As has been found with adults, infants exposed to this condition were unable to discriminate the contrast-reversed shading and cast shadow figures. Our results suggested that an age of around 7 months is important for development of the ability to perceive shape differences from shading and cast shadows.
阴影是形状感知中的强大线索。我们能够隐式地感知明暗和投射阴影。我们研究了婴儿检测由明暗或投射阴影描绘的单个差异图形的能力，并考察了阴影对比度极性对这一过程的影响。在实验1中，我们操纵阴影的模糊方向以创建看起来像是部分被遮蔽或投射阴影的刺激，然后使用偏好测试这种差异是否能让5至8个月大的婴儿区分成年人能够感知为不同形状的图形。只有7至8个月大的婴儿能够区分一个明暗图形与投射阴影图形，反之亦然。在实验2中，我们颠倒了图形的对比度极性（深色物体带有浅色阴影），并测试辨别力是否受到影响。正如在成年人中发现的那样，处于这种条件下的婴儿无法区分对比度反转的明暗和投射阴影图形。我们的结果表明，大约7个月大对于从明暗和投射阴影中感知形状差异的能力发展很重要。
