A comparison of rural and urban Indian children's visual detection of threatening and nonthreatening animals

Recent studies indicate that young children preferentially attend to snakes, spiders, and lions compared with nondangerous species, but these results have yet to be replicated in populations that actually experience dangerous animals in nature. This multi‐site study investigated the visual‐detection biases of southern Indian children towards two potentially dangerous taxa, snakes and lions, that constituted major threats during human evolution. Three‐ to 8‐year‐old children from two distinct populations were presented with visual‐search tasks containing one target image embedded in matrices of eight distractor images. Children living in Bangalore city, an urban setting in which exposure to dangerous animals would only occur occasionally during family outings to zoos and forest areas, were compared with children living in and around National Parks where exposure to dangerous species is frequent. In the first two experiments, children from both locations detected snake and lion images more rapidly than nonthreatening lizard and antelope images, respectively. Neither urban nor rural children displayed a bias for detecting horses versus cows, the latter constituting a familiar animal with strong religious significance. For all three experiments, the reaction times of urban and rural children were very similar, indicating that periodic exposure to dangerous animals early in life, coupled with adult cautioning, did not facilitate better snake and lion detection. This consistency of urban and rural children with different exposure to dangerous animals suggests that detection of some dangerous species may reflect both experience in nature and visual biases shaped by natural selection.     

威胁性刺激蛇一定会被更快觉察吗?蛇与蜥蜴的对比

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。     

Context and Animal Behavior III: The Relationship Between Early Development and Evolutionary Persistence of Ground Squirrel Antisnake Behavior

California ground squirrel pups are frequent prey of northern Pacific rattlesnakes and Pacific gopher snakes. Although pups innately recognize that snakes are dangerous, they exhibit adult-like antisnake behaviors that are perilous. For the most part, adults apply antisnake behaviors to directly or indirectly protect pups. Two experiments using video investigated the evolutionary and developmental stability of antisnake behavior with the aim of identifying genetic and epigenetic factors that could account for its precocious, but dangerous expression. In Experiment 1, adult squirrels from Folsom Lake where rattlesnake and gopher snakes are abundant were compared with squirrels from Lake Tahoe and Mount Shasta where these snakes are absent and whose ancestors may have experienced relaxed selection from snakes spanning an estimated 300,000 years. Squirrels interacted with a caged rattlesnake or gopher snake for alternate 5-min trials in a laboratory setting. The results of this experiment revealed that the antisnake behaviors of Lake Tahoe and Mount Shasta squirrels were not substantially different from the Folsom Lake squirrels, a finding that suggests low heritability. In Experiment 2, lab-born pups from Folsom Lake were alternately exposed for 5-min trials to a caged gopher snake and guinea pig. The findings from this experiment indicated that visual recognition of snakes had a sharp onset at 40 to 41 days of age, the first day each pup showed evidence of pattern vision. In other rodents, this developmental period shortly after eye opening coincides with major dendritic growth and leveling off interneural connectivity in visual cortex. In ground squirrels, the early expression of antisnake behaviors that function more effectively in adults than in pups could reflect the requirements shaped by natural selection for the reliable emplacement of neural circuitry subserving snake recognition during the initial, less variable period of neuronal outgrowth.     

Detecting the snake in the grass: attention to fear-relevant stimuli by adults and young children

Snakes are among the most common targets of fears and phobias. In visual detection tasks, adults detect their presence more rapidly than the presence of other kinds of visual stimuli. We report evidence that very young children share this attentional bias. In three experiments, preschool children and adults were asked to find a single target picture among an array of eight distractors. Both the children and the adults detected snakes more rapidly than three types of nonthreatening stimuli (flowers, frogs, and caterpillars). These results provide the first evidence of enhanced visual detection of evolutionarily relevant threat stimuli in young children.     

Superior detection of threat-relevant stimuli in infancy

The ability to quickly detect potential threat is an important survival mechanism for humans and other animals. Past research has established that adults have an attentional bias for the detection of threat-relevant stimuli, including snakes and spiders as well as angry human faces. Recent studies have documented that preschool children also detect the presence of threatening stimuli more quickly than various non-threatening stimuli. Here we report the first evidence that this attentional bias is present even in infancy. In two experiments, 8- to 14-month-old infants responded more rapidly to snakes than to flowers and more rapidly to angry than to happy faces. These data provide the first evidence of enhanced visual detection of threat-relevant stimuli in infants and hence offer especially strong support for the existence of a general bias for the detection of threat in humans.     

Snakes and cats in the flower bed: fast detection is not specific to pictures of fear-relevant animals

The observation that snakes and spiders are found faster among flowers and mushrooms than vice versa and that this search advantage is independent of set size supports the notion that fear-relevant stimuli are processed preferentially in a dedicated fear module. Experiment 1 replicated the faster identification of snakes and spiders but also found a set size effect in a blocked, but not in a mixed-trial, sequence. Experiment 2 failed to find faster identification of snake and spider deviants relative to other animals among flowers and mushrooms and provided evidence for a search advantage for pictures of animals, irrespective of their fear relevance. These findings suggest that results from the present visual search task cannot support the notion of preferential processing of fear relevance.     

The influence of animal fear on attentional capture by fear-relevant animal stimuli in children

The present study demonstrated that pictures of fear-relevant animals, snakes and spiders, presented among backgrounds of other animal stimuli captured attention and interfered in the detection of a neutral target to the same extent in a large sample of unselected children (N=81). Moreover, detection of a neutral target animal was slowed more in the presence of a feared fear-relevant distracter, e.g., a snake for snake fearful children, than in the presence of a not feared fear-relevant distracter, e.g., a spider for snake fearful children. These results indicate attentional capture by phylogenetically fear-relevant animal stimuli in children and the selective enhancement of this effect by fear of these animals. These findings are consistent with current models of preferential processing of phylogenetically prepared threat stimuli and with cognitive models of anxiety that propose an enhancing effect of fear in the processing of fear-related stimuli.     

Individual differences in the shape bias in preschool children with specific language impairment and typical language development: theoretical and clinical implications

We investigated whether preschool children with specific language impairment (SLI) exhibit the shape bias in word learning: the bias to generalize based on shape rather than size, color, or texture in an object naming context (‘This is a wek; find another wek’) but not in a non‐naming similarity classification context (‘See this? Which one goes with this one?’). Fifty‐four preschool children (16 with SLI, 16 children with typical language [TL] in an equated control group, and 22 additional children with TL included in individual differences analyses but not group comparisons) completed a battery of linguistic and cognitive assessments and two experiments. In Experiment 1, children made generalization choices in object naming and similarity classification contexts on separate days, from options similar to a target object in shape, color, or texture. On average, TL children exhibited the shape bias in an object naming context, but children with SLI did not. In Experiment 2, we tested whether the failure to exhibit the shape bias might be linked to ability to detect systematicities in the visual domain. Experiment 2 supported this hypothesis, in that children with SLI failed to learn simple paired visual associations that were readily learned by children with TL. Analyses of individual differences in the two studies revealed that visual paired‐associate learning predicted degree of shape bias in children with SLI and TL better than any other measure of nonverbal intelligence or standard assessments of language ability. We discuss theoretical and clinical implications.     

Are the aesthetic preferences towards snake species already formed in pre-school aged children?

This study explores aesthetic preferences towards boa and python species among pre-school children and adults, and compares the ratings between the two groups. A set of snake photographs was presented (56 species) to children and adult respondents. The respondents were asked to select the five most preferred and five least preferred species. The children’s agreement on which species were ‘beautiful’ and which were ‘ugly’ was statistically significant and a positive relationship between the mean ranks provided by children and adults was also found (r = .54, P < .001). Children preferred species with thick necks and inconspicuous heads, usually small species, harmless to children. Large pythons probably posed more danger to children than they did to adults during human evolution in African savannas and therefore we hypothesize that young children’s aesthetic preferences were shaped by natural selection through interactions with dangerous snakes.     

Snake mating systems, behavior, and evolution: the revisionary implications of recent findings

Sexual selection and mating systems profoundly influence the behavior and psychology of animals. Using their own studies of green anacondas (Eunectes murinus) and reviewing other recent studies, the authors conclude that incomplete data derived from a few well-studied snake species have led to general acceptance of polygyny as the dominant mating system in snakes. New data on behavior, paternity, and life history in a diverse taxonomic array of snakes support the view that polyandry is not only common in snakes but may have been the ancestral mating system. This interpretation helps to explain many seemingly paradoxical behavioral differences between lizards and snakes, such as the lack of territorial systems in most snakes and their frequent female-biased sexual size dimorphism.     

Rapid discrimination of visual patterns in children and adults

Rapid visual discrimination in children (9 to 11 yr.) and adults was investigated using two tasks in which the subject had to search for a target pattern embedded in 35 background patterns. The time available for inspecting the search arrays was altered by varying the stimulus duration. In one task, there was a large difference in the feature or 'texton' content of patterns between the target and the background; in the other, this difference was small. In the first task, the children could detect the target pattern in a briefly flashed search array with high accuracy, because the target 'popped out' perceptually from the array, but in the second task the same detection rate was not reached until the stimulus duration was much longer, since a serial searching strategy was required. Results achieved by children and adults were similar. It seems that serial visual search is as efficient in children as in adults.     

Cross-cultural differences in cognitive development: attention to relations and objects

Growing evidence indicates a suite of generalized differences in the attentional and cognitive processing of adults from Eastern and Western cultures. Cognition in Eastern adults is often more relational and in Western adults is more object focused. Three experiments examined whether these differences characterize the cognition of preschool children in the two cultures. In Experiment 1, 4-year-olds from the two cultures (N=64) participated in a relational match-to-standard task in two conditions, with simple or richly detailed objects, in which a focus on individual objects may hurt performance. Rich objects, consistent with past research, strongly limited the performance of U.S. children but not Japanese children. In Experiment 2, U.S. and Japanese 4-year-olds (N=72) participated in a visual search task that required them to find a specific object in a cluttered, but organized as a scene, visual field in which object-centric attention might be expected to aid performance and relational attentional pattern may hinder the performance because of relational structure that was poised by the scene. U.S. children outperformed Japanese children. In Experiment 3, 4-year-olds from both cultures (N=36) participated in a visual search task that was similar to Experiment 2 but with randomly placed objects, where there should not be a difference between the performance of two cultures because the relational structure that may be posed by the scene is eliminated. This double-dissociation is discussed in terms of implications for different developmental trajectories, with different developmental subtasks in the two cultures.     

What's so special about slithering serpents? Children and adults rapidly detect snakes based on their simple features

Snakes are among the most common targets of fears and phobias around the world. In visual search tasks, both adults and young children have repeatedly been found to visually detect snakes more rapidly than other kinds of stimuli. An important question that remains unstudied is what accounts for humans’ rapid response to snakes? Here we suggest that specific features of snakes themselves lead to their rapid detection. The results of five experiments suggest that a snake's shape is the crucial factor in their rapid detection.     

When danger lurks in the background: attentional capture by animal fear-relevant distractors is specific and selectively enhanced by animal fear

Across 2 experiments, a new experimental procedure was used to investigate attentional capture by animal fear-relevant stimuli. In Experiment 1 (N=34), unselected participants were slower to detect a neutral target animal in the presence of a spider than a cockroach distractor and in the presence of a snake than a large lizard distractor. This result confirms that phylogenetically fear-relevant animals capture attention specifically and to a larger extent than do non-fear-relevant animals. In Experiment 2 (N=86), detection of a neutral target animal was slowed more in the presence of a feared fear-relevant distractor (e.g., a snake for snake-fearful participants) than in presence of a not-feared fear-relevant distractor (e.g., a spider for snake-fearful participants). These results indicate preferential attentional capture that is specific to phylogenetically fear-relevant stimuli and is selectively enhanced in individuals who fear these animals.     

不受知觉负载调节的注意捕获效应：生态信息的作用

快速探测到环境中具有生态意义的信息是适应性行为的一种重要表现。本研究采用注意捕获范式检验具有生态意义的信息是否能够被注意系统自动化加工。具体而言, 我们考察对负性面孔中的生态意义信息的加工是否受任务和知觉负载的影响。在实验一中, 我们发现负性面孔相对于中性面孔在高低知觉负载下的注意捕获能力没有显著差异, 表明负性面孔在高低负载下都具有加工优先性。为了分离刺激突显性与生态意义二个因素对实验结果的影响, 在实验二中, 我们将负性面孔刺激替换为具有突显性但不含有生态信息的颜色块刺激, 发现颜色块在高知觉负载下的注意捕获效应显著低于低负载, 即知觉负载能够显著影响其注意捕获能力, 表明负性面孔在实验一中的效应应归因于其本身携带的生态信息。由此, 本研究展示了具有生态意义的视觉刺激能够得到视觉系统的自动化加工。     

Reliance on visual and verbal information across ontological kinds: What do children know about animals and machines?

In two experiments, we systematically examined the reliance on visual (external shape and features) and verbal (origins and internal structure) information in isolation, and together in the identification of animals and machines by 3-, 4-, and 5-year-olds, and adults. Experiment 1 examined the use of visual and verbal information independently in a visual classification task, a verbal classification task, and an induction task. Experiment 2 examined the relative weighting of visual and verbal information in an induction task and a categorization task. The three most important findings from Experiment 1 were that (a) children and adults can use either visual or verbal information to distinguish animals from machines; (b) all age groups classified items with mixed visual information as machines, a tendency that increased with age; and (c) with age, children became increasingly able to induce non-obvious properties, especially the non-obvious properties of machines. The findings from Experiment 2 indicate that the youngest and oldest participants relied on both visual and verbal information in the identification of animals and machines in categorization and induction tasks. Five-year-olds, however, relied only on visual information. As in Experiment 1, we observed a tendency to judge items with contrasting information as machines, suggesting that individuals utilize a more strict definition (both visually and verbally) for the category of animals. We discuss the implication of these results with respect to developmental differences in the use of perceptual and conceptual information across the ontological distinction between artifacts and natural kinds.     

Visual search for emotional faces in children

The ability to rapidly detect facial expressions of anger and threat over other salient expressions has adaptive value across the lifespan. Although studies have demonstrated this threat superiority effect in adults, surprisingly little research has examined the development of this process over the childhood period. In this study, we examined the efficiency of children's facial processing in visual search tasks. In Experiment 1, children (N=49) aged 8 to 11 years were faster and more accurate in detecting angry target faces embedded in neutral backgrounds than vice versa, and they were slower in detecting the absence of a discrepant face among angry than among neutral faces. This search pattern was unaffected by an increase in matrix size. Faster detection of angry than neutral deviants may reflect that angry faces stand out more among neutral faces than vice versa, or that detection of neutral faces is slowed by the presence of surrounding angry distracters. When keeping the background constant in Experiment 2, children (N=35) aged 8 to 11 years were faster and more accurate in detecting angry than sad or happy target faces among neutral background faces. Moreover, children with higher levels of anxiety were quicker to find both angry and sad faces whereas low anxious children showed an advantage for angry faces only. Results suggest a threat superiority effect in processing facial expressions in young children as in adults and that increased sensitivity for negative faces may be characteristic of children with anxiety problems.     

Imagery in the congenitally blind: how visual are visual images?

Three experiments compared congenitally blind and sighted adults and children on tasks presumed to involve visual imagery in memory. In all three, the blind subjects' performances were remarkably similar to the sighted. The first two experiments examined Paivio's (1971) modality-specific imagery hypothesis. Experiment 1 used a paired-associate task with words whose referents were high in either visual or auditory imagery. The blind, like the sighted, recalled more high-visual-imagery pairs than any others. Experiment 2 used a free-recall task for words grouped according to modality-specific attributes, such as color and sound. The blind performed as well as the sighted on words grouped by color. In fact, the only consistent deficit in both experiments occurred for the sighted in recall of words whose referents are primarily auditory. These results challenge Paivio's theory and suggest either (a) that the visual imagery used by the sighted is no more facilitating than the abstract semantic representations used by the blind or (b) that the sighted are not using visual imagery. Experiment 3 used Neisser and Kerr's (1973) imaging task. Subjects formed images of scenes in which target objects were described as either visible in the picture plane or concealed by another object and thus not visible. On an incidental recall test for the target objects, the blind, like the sighted, recalled more pictorial than concealed targets. This finding suggests that the haptic images of the blind maintain occlusion just as the visual images of the sighted do.     

The lurking snake in the grass: Interference of snake stimuli in visually taxing conditions

Based on evolutionary considerations, it was hypothesized that humans have been shaped to easily spot snakes in visually cluttered scenes that might otherwise hide camouflaged snakes. This hypothesis was tested in a visual search experiment in which I assessed automatic attention capture to evolutionarily-relevant distractor stimuli (snakes), in comparison with another animal which is also feared but where this fear has a disputed evolutionary origin (spiders), and neutral stimuli (mushrooms). Sixty participants were engaged in a task that involved the detection of a target (a bird) among pictures of fruits. Unexpectedly, on some trials, a snake, a spider, or a mushroom replaced one of the fruits. The question of interest was whether the distracting stimuli slowed the reaction times for finding the target (the bird) to different degrees. Perceptual load of the task was manipulated by increments in the set size (6 or 12 items) on different trials. The findings showed that snake stimuli were processed preferentially, particularly under conditions where attentional resources were depleted, which reinforced the role of this evolutionarily-relevant stimulus in accessing the visual system (Isbell, 2009).     

Selective associations in the observational conditioning of fear in rhesus monkeys

Three experiments explored the issue of selective associations in the observational conditioning of fear. Experiment 1 results indicated that observer rhesus monkeys acquired a fear of snakes through watching videotapes of model monkeys behaving fearfully with snakes. In Experiment 2, observers watched edited videotapes that showed models reacting either fearfully to toy snakes and nonfearfully to artificial flowers (SN+/FL-) or vice versa (FL+/SN-). SN+/FL- observers acquired a fear of snakes but not of flowers; FL+/SN- observers did not acquire a fear of either stimulus. In Experiment 3, monkeys solved complex appetitive discriminative (PAN) problems at comparable rates regardless of whether the discriminative stimuli were the videotaped snake or the flower stimuli used in Experiment 2. Thus, monkeys appear to selectively associate snakes with fear.