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Kazuki Sato, So Kanazawa, Masami Yamaguchi; Infants can recognize the lightness change in cast shadows. Journal of Vision 2016;16(12):63. doi: https://doi.org/10.1167/16.12.63.
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© ARVO (1962-2015); The Authors (2016-present)
When an object goes through cast shadows, humans perceive that the object's lightness becomes darker because the object's light sources are blocked. This observation suggests that adults perceive the change of an object's lightness in shadows based on the assumption that the surface of an object is darker when in shadows. In the current study, we investigated whether 5- to 8-month-old infants also use this assumption to perceive the lightness of the object's surface in shadows. In Experiment 1, we created a CG movie of a duck going through cast shadows. In this movie, the lightness of the duck's surface was darker while the duck was within the two shadows. We then created an "unnatural movie" in which the lightness of the duck's surface inside and outside of the shadows was reversed. If infants, like adults, use the "shadow assumption" to perceive the object's lightness in shadows, the infants would detect the unnatural lightness change. We compared infants' looking preference for the natural and unnatural movies and tested their preference for the unnatural movie using Csibra (2001)'s method. Our results showed that 7- to 8-month-olds preferred the unnatural movie, but 5- to 6-month-olds did not show this preference. The results revealed that only 7- to 8-month-old infants could detect the unnatural change of the lightness of the duck's surface. In Experiment 2, we created a movie without shadows to examine whether infants' preference in Experiment 1 was based on just a lightness change without context. We used the same procedure as in Experiment 1 and the results showed that no infants showed any preference in Experiment 2. These results suggest that 7- to 8-month-old infants do perceive an object's lightness with the assumption that the surface of an object is darker when in shadows.
Meeting abstract presented at VSS 2016
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