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The Hidden Snake in the Grass: Superior Detection of Snakes in Challenging Attentional Conditions.

Soares SC, Lindström B, Esteves F, Ohman A - PLoS ONE (2014)

Bottom Line: Furthermore, bites by venomous snakes still cause significant morbidity and mortality in tropical regions of the world.Our results demonstrate a striking independence of snake detection from ecological factors that impede the detection of other stimuli, which suggests that, consistent with the SDT, they reflect a specific biological adaptation.Nonetheless, the empirical tests we report are limited to only one aspect of this rich theory, which integrates findings across a wide array of scientific disciplines.

View Article: PubMed Central - PubMed

Affiliation: Department of Education, University of Aveiro, Aveiro, Portugal; IBILI - Institute for Biomedical Imaging and Life Sciences, Faculty of Medicine, University of Coimbra, Coimbra, Portugal; Center for Health Technology and Services Research (CINTESIS), Faculty of Medicine, University of Porto, Porto, Portugal.

ABSTRACT
Snakes have provided a serious threat to primates throughout evolution. Furthermore, bites by venomous snakes still cause significant morbidity and mortality in tropical regions of the world. According to the Snake Detection Theory (SDT Isbell, 2006; 2009), the vital need to detect camouflaged snakes provided strong evolutionary pressure to develop astute perceptual capacity in animals that were potential targets for snake attacks. We performed a series of behavioral tests that assessed snake detection under conditions that may have been critical for survival. We used spiders as the control stimulus because they are also a common object of phobias and rated negatively by the general population, thus commonly lumped together with snakes as "evolutionary fear-relevant". Across four experiments (N = 205) we demonstrate an advantage in snake detection, which was particularly obvious under visual conditions known to impede detection of a wide array of common stimuli, for example brief stimulus exposures, stimuli presentation in the visual periphery, and stimuli camouflaged in a cluttered environment. Our results demonstrate a striking independence of snake detection from ecological factors that impede the detection of other stimuli, which suggests that, consistent with the SDT, they reflect a specific biological adaptation. Nonetheless, the empirical tests we report are limited to only one aspect of this rich theory, which integrates findings across a wide array of scientific disciplines.

No MeSH data available.


Related in: MedlinePlus

Experiment 1: Mean accuracy proportions to locate a discrepant target stimulus that could be a Snake, a Spider, or a Mushroom, in displays exposed for 300 ms, 600 ms, and 1200 ms that included eight (a) or four items (b).
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pone-0114724-g003: Experiment 1: Mean accuracy proportions to locate a discrepant target stimulus that could be a Snake, a Spider, or a Mushroom, in displays exposed for 300 ms, 600 ms, and 1200 ms that included eight (a) or four items (b).

Mentions: The results from the accuracy data concurred with those from the RT data with one important addition. In contrast to the RT data, the three-way interaction between target, exposure duration, and set size was also significant, F (4, 204) = 6.69, p<.0001, suggesting that the difference between snakes and spiders was larger with many rather than few distractors (see Fig. 3). More specifically, the detection of snakes was more accurate than detection of spiders and mushrooms, particularly at the shortest stimulus duration (300 ms) and when embedded among 8 rather than 4 distractor pictures (fruits). Snakes were more accurately detected than spiders (and mushrooms) only with 8 item stimulus set (Fig. 3, upper panel), and the 300 and 600 ms duration stimuli (p<.001 for both comparisons). Snakes were always more accurately detected than mushrooms (p<.05), whereas spiders were more accurately detected than mushrooms only for the 300 ms-small display condition (Fig. 3, lower left panel).


The Hidden Snake in the Grass: Superior Detection of Snakes in Challenging Attentional Conditions.

Soares SC, Lindström B, Esteves F, Ohman A - PLoS ONE (2014)

Experiment 1: Mean accuracy proportions to locate a discrepant target stimulus that could be a Snake, a Spider, or a Mushroom, in displays exposed for 300 ms, 600 ms, and 1200 ms that included eight (a) or four items (b).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4262429&req=5

pone-0114724-g003: Experiment 1: Mean accuracy proportions to locate a discrepant target stimulus that could be a Snake, a Spider, or a Mushroom, in displays exposed for 300 ms, 600 ms, and 1200 ms that included eight (a) or four items (b).
Mentions: The results from the accuracy data concurred with those from the RT data with one important addition. In contrast to the RT data, the three-way interaction between target, exposure duration, and set size was also significant, F (4, 204) = 6.69, p<.0001, suggesting that the difference between snakes and spiders was larger with many rather than few distractors (see Fig. 3). More specifically, the detection of snakes was more accurate than detection of spiders and mushrooms, particularly at the shortest stimulus duration (300 ms) and when embedded among 8 rather than 4 distractor pictures (fruits). Snakes were more accurately detected than spiders (and mushrooms) only with 8 item stimulus set (Fig. 3, upper panel), and the 300 and 600 ms duration stimuli (p<.001 for both comparisons). Snakes were always more accurately detected than mushrooms (p<.05), whereas spiders were more accurately detected than mushrooms only for the 300 ms-small display condition (Fig. 3, lower left panel).

Bottom Line: Furthermore, bites by venomous snakes still cause significant morbidity and mortality in tropical regions of the world.Our results demonstrate a striking independence of snake detection from ecological factors that impede the detection of other stimuli, which suggests that, consistent with the SDT, they reflect a specific biological adaptation.Nonetheless, the empirical tests we report are limited to only one aspect of this rich theory, which integrates findings across a wide array of scientific disciplines.

View Article: PubMed Central - PubMed

Affiliation: Department of Education, University of Aveiro, Aveiro, Portugal; IBILI - Institute for Biomedical Imaging and Life Sciences, Faculty of Medicine, University of Coimbra, Coimbra, Portugal; Center for Health Technology and Services Research (CINTESIS), Faculty of Medicine, University of Porto, Porto, Portugal.

ABSTRACT
Snakes have provided a serious threat to primates throughout evolution. Furthermore, bites by venomous snakes still cause significant morbidity and mortality in tropical regions of the world. According to the Snake Detection Theory (SDT Isbell, 2006; 2009), the vital need to detect camouflaged snakes provided strong evolutionary pressure to develop astute perceptual capacity in animals that were potential targets for snake attacks. We performed a series of behavioral tests that assessed snake detection under conditions that may have been critical for survival. We used spiders as the control stimulus because they are also a common object of phobias and rated negatively by the general population, thus commonly lumped together with snakes as "evolutionary fear-relevant". Across four experiments (N = 205) we demonstrate an advantage in snake detection, which was particularly obvious under visual conditions known to impede detection of a wide array of common stimuli, for example brief stimulus exposures, stimuli presentation in the visual periphery, and stimuli camouflaged in a cluttered environment. Our results demonstrate a striking independence of snake detection from ecological factors that impede the detection of other stimuli, which suggests that, consistent with the SDT, they reflect a specific biological adaptation. Nonetheless, the empirical tests we report are limited to only one aspect of this rich theory, which integrates findings across a wide array of scientific disciplines.

No MeSH data available.


Related in: MedlinePlus