Evolutionary-based threat modulates perception of looming visual stimuli in human infants

Abstract

Research with both human and non-human primates suggests that the visual system exhibits specialized processing of evolutionary-based threats. Adult humans (Ohman & Mineka, 2001) and monkeys (Shibasaki & Kawai, 2009) detect images of snakes and spiders faster than neutral images during visual search. Moreover, human infants orient more quickly to a threatening compared to a non-threatening image, when presented with two images simultaneously (e.g., a snake and a flower). Taken together, these results suggest a perceptual bias for threat that exists prior to the development of overt fear and that may be innate in human development (LoBue & DeLoache, 2009). Yet differential orientating in infants and visual search paradigms typically used with adult humans and nonhuman primates are heavily dependent on contrast images; there are also influences of stimulus familiarity and strategic processes (Frischen, Eastwood, & Smilek, 2008), raising questions about the mechanisms underlying the perceptual basis of sensitivity to evolutionarily-based threats. The current study extends existing research by examining infants’ defensive blinking in a visual looming paradigm. We tested 60 6- to 12- month-old infants. Infants were presented with images of snakes, spiders, rabbits, and butterflies. Each image loomed towards them, one at a time, at six velocities, creating different time-to-contacts (TTCs). As in previous studies (Kayed & van der Meer, 2000), analyses revealed that infants’ blinks scaled according to TTC. We also found that defensive blinking was modulated by the threat value of stimuli. Infants blinked sooner to snakes and spiders compared to rabbits and butterflies at all TTCs (ps < .05). Critically, this effect cannot be accounted for by familiarity, as infants looked longer overall to the non-threatening than threatening animals (p < .05). That infants’ defensive blinks were modulated by the threat value of the animal provides evidence for specialized spatiotemporal perceptual processing of evolutionary-based threat. Meeting abstract presented at VSS 2015