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.     

The function of dendritic spines: a review of theoretical issues

The discovery of dendritic spines in the late nineteenth century has prompted nearly 90 years of speculation about their physiological importance. Early observations that bulbous spine heads had very close approximations with the axon terminals of other neurons, confirmed later by ultrastructural study, led to ideas that spines enhance dendritic surface areas for making synaptic contacts. More recent application of cable and core-conductor theory to the anatomical study of spines has raised a number of new ideas about spine function. One important issue was derived from the theoretical treatment of spines as tiny dendrites with much higher input resistances than those of the larger parent dendrites. The high spine-stem resistance results in relative electrical isolation of the spine head; this causes large local depolarizations in the spine head. Several theoretical studies have also shown that if the spine-head input resistances are substantially higher than those of the parent dendrites, spines have the potential for modulating a host of biochemical and biophysical processes that might regulate synaptic efficacy. Empirical studies have documented that spine heads increase rapidly in size after afferent projections have been stimulated electrically and after animals have engaged in a single bout of ecologically important behavioral activity. Such spine head enlargement dilates the portion of the spine stem adjacent to the spine head and this process shortens the spine stem without appreciably altering overall spine length. Theoretical study shows that spine-stem shortening lowers the spine-head input resistance relative to the branch input resistance. This reduction in input resistance can enhance the transfer of electrical charge from the spine head to the parent dendrite, especially when the synaptic conductance is large relative to the spine-head input conductance. Spine-stem shortening also lowers the peak transient membrane potential in the spine head and this factor could delimit Ca2+ influx into the spine head via voltage-dependent Ca2+ channels. The modulation of Ca2+ influx by spine-stem shortening has the potential for regulating Ca2+-sensitive enzymatic activity in the spine head that could affect phosphorylation of cytoskeletal proteins maintaining spine shape and phosphorylation of proteins in the postsynaptic density. Finally, theoretical findings are described that examine the effects of voltage-dependent inward-current channels in the spine head and their ability to amplify the charge transfer due to transmitter-dependent synaptic conductances.     

Rapid detection of visually provocative animals by preschool children and adults

The ability to detect dangerous animals rapidly in complex landscapes has been historically important during human evolution. Previous research has shown that snake images are more readily detected than images of benign animals. To provide a stringent test of superior snake detection in preschool children and adults, Experiment 1 consisted of two parts using a touch-screen visual search task. Reaction times to detect different target snakes embedded in matrices of lizards were compared with reaction times to detect target lizards embedded in matrices of snakes. Experiment 2 compared the visual salience of lions with that of similarly colored antelopes. This experiment tested the prediction that historically dangerous felid predators would also engender rapid detection. Results from the two experiments revealed that both preschool children and adults located snakes and lions more quickly than their nonthreatening counterparts. Experiment 3 examined the ability of children and adults to distinguish between similar appearing cows and horses. Preschool children and adult men exhibited no reliable differences in detecting the two animal types. Adult women located horses reliably faster than cows, suggesting that visual biases for some animals can be acquired after childhood.     

Recognition of heterospecific alarm vocalizations by bonnet macaques (Macaca radiata)

Recognition of heterospecific alarm vocalizations is an essential component of antipredator behavior in several prey species. The authors examined the role of learning in the discrimination of heterospecific vocalizations by wild bonnet macaques (Macaca radiata) in southern India The bonnet macaques' flight and scanning responses to playbacks of their own alarm vocalizations were compared with their responses to playbacks of vocalizations of Nilgiri langurs (Trachypithecus johnii), Hanuman langurs (Semnopithecus entellus), and sambar deer (Cervus unicolor). The study was conducted in 3 regions that differed in the frequency with which bonnet macaques encountered these species and included an urban setting. Call recognition was highest in adults and in regions where individuals were frequently exposed to the calling species; calls were not recognized by urban monkeys. Thus, age and experience are important factors in heterospecific call recognition by bonnet macaques.     

Questionnaire of executive function for dancers: an ecological approach

There is a current debate about the ecological validity of executive function (EF) tests. Consistent with the verisimilitude approach, this research proposes the ballet executive scale (BES), a self-rating questionnaire that assimilates idiosyncratic executive behaviors of classical dance community. The BES was administrated to 149 adolescents, students of the Cuban Ballet School. Results present a Cronbach's alpha coefficient of .80 and a split-half Spearman-Brown coefficient r (SB) = .81. An exploratory factor analysis describes a bifactorial pattern of EF dimensions, with a self-regulation component, which explains more than 40% of variance, and a Developmental component, which accounts for more than 20% of variance. The questionnaire's total scores fit linear regression models with two external criteria of academic records, confirming concurrent validity. These findings support the hypothesis that the internalization of specific contextual cultural meanings has a mediating influence in the development of EF.     

Thatcher and the Cheshire cat: context and the processing of facial features

As has been noted before, a face made gruesome by the inversion of its mouth will not be so perceived when the entire construction is inverted. Results are presented which suggest that this is because the mouth and eye features are evaluated individually (although each feature may influence the evaluation of the other) and the mouth, whether normal or inverted, tends to have its uppermost part assigned as 'top', providing for either a pleasant smiling-mouth expression or a gruesome 'biting-intention' expression. However, the gruesomeness of an inverted mouth is attenuated when eyes are shown below it (producing an inverted smiling face) which suggests that the location of other facial features can also influence the assignments of 'top'.