Abstract:

Previous research shows that preschool children detect snakes quickly than non-threating stimuli (e.g. flowers). In this study, we used eye tracking technology to provide direct evidences about the superior detection about threat-relevant stimuli. Two experiments were designed to testify whether the snakes would be fixated faster and quickly by preschool children and adults. In addition, we also used line drawing snakes and flowers as stimuli to control the shape of snakes and to testify the perceptual template hypothesis. In experiment 1, sixteen 4- to 6-year-old preschool children and 22 undergraduates were recruited as participants. A revised 3 × 3 matrices of color photographs of threat-relevant (snakes) and threat-irrelevant (flowers) stimuli were presented to both preschool children and adults. All participants were asked to find the threat target (snake) among seven non-threat distractors (flowers) and vice versa. Sixteen matrices with 8 pictures (1 target and 7 distractors) were presented to the participants. We changed the standard visual search task that did not present stimuli in the middle of the 3 × 3 matrices to control the central location effect and make the procedure appropriate for eye tracking calibration. It’s a 2 (age: children, adults)× 2 (target: snake, flower) mixed design, and age was the between subject variable. In experiment 2, we improved the stimuli with line drawings to pop out the continuous curvilinear contour of snakes. The design, presentation method was the same as experiment 1. In two experiments, Tobii T120 Eye tracker was used to record the viewing behaviors of adults and children. The results of experiment 1 indicated that both the preschool children and adults fixated snakes faster and with less fixation counts than flowers, and their first fixation duration was shorter on snakes than flowers. Adults performed faster fixation, much less fixation counts than children. As distractors (flower was target), snakes were also fixated quickly than flowers (snake was target). In experiment 2, the same results were found that both children and adults located line drawing snakes quicker than line drawing flowers. And the first fixation duration to snakes were much shorter than flowers. Adults still fixated faster than children. For the snakes as distractors, we found the same results as experiment 1. Compared to the fixations of the line drawing snakes without color and pattern in experiment 2, real and colorful snakes in experiment 1 were fixated faster. The real and colorful snakes were detected faster and with less fixation counts before they were located as distractors. In conclusion, even preschool children who have little snake experience also show faster attention orienting and shorter attention holding. Based on the eye movements evidences, the continuous curvilinear shape plays an important role in the snake relevant threat detection. The eye fixations of line drawing snakes provide direct evidence to the perceptual template theory. To be a special reptile, the color, patterns can boost the quick detection.

Key words: snakes, threat-relevant stimuli, preschool children, detection, eye movements