威胁性刺激蛇一定会被更快觉察吗?蛇与蜥蜴的对比

Attentional Biases Are Not Always Specific to Fear-relevant Stimuli: Snakes vs Lizards

大量运用视觉搜索范式的研究发现,在进化过程中对人类生存具有威胁的蛇会被人们更快地觉察。但已有研究采用动物(蛇)植物(花)配对搜索的方式,而很少直接采用近似的动物配对搜索。本研究选取成人大学生被试,通过视觉搜索范式和眼动追踪,对比了蛇和同为爬行类动物、却不具有进化上威胁性的蜥蜴的视觉搜索过程,以探究蛇的威胁性和动物特征相似性在威胁性刺激注意偏向中的作用。实验1采用蛇和蜥蜴互为目标物和干扰物,发现相对于蛇,被试对蜥蜴的行为反应时更短;首次注视到达时间也更短。实验2-4分别采用黑白和线画刺激、恒定干扰物(花和青蛙)、使用自然背景材料对比蛇和蜥蜴的觉察,发现了一致的结果,即被试对蜥蜴的视觉搜索时间和行为反应时间都要快于蛇。在视觉搜索任务中当两种视觉刺激材料的属性接近时,蛇在进化上的威胁性不一定导致更快的搜索时间,而刺激物的视觉特征对目标物的觉察会产生重要的影响。

Studies have found that fear-relevant snakes can be detected rapidly during visual search. In this study, by comparing snakes and lizards, which also belong to reptiles but have no threat to human in evolution, four ex- periments were conducted to explore whether snakes would be detected rapidly. Eye tracking technique was used in visual search tasks to record participants＇ visual search process. In experiment 1, a series of 3 - 3 matrices of eight colored photographs of snakes or lizards were presented on the screen, without stimulus in the middle. Participants were asked to find out the target （snake） among seven distractors （lizards） and vice versa. Experiment 2 used gray-scale and line-drawing pictures to further investigate snake＇s low-level perceptual features played in attention detection. To balance the impact of different distraetors in experiment 1 and 2, another 24 participants were reques- ted to detect snake or lizard among the uniform distractors （flowers or frogs） in experiment 3. To improve the eco- logical validity, snakes＇ and lizards＇ photos with natural scenes were used in experiment 4. The results of reaction time and eye-movements in experiment 1 indicate that when searching for lizards, attention can be attracted more quickly to targets. Experiment 2 to 4 replicated the key finding of experiment 1. Moreover, awareness of the targets can be promoted with the color and the texture of the lizards and the snakes. The similarities of targets and distrae- tots will hinder the search to the targets. In conclusion, attentional biases are not always specific to snakes, the na- ture of animal and the perceptual features of the target can influence the fear-related stimuli detection.