Infants’ responsiveness to lightness changes on a dynamic three-dimensional surface

In a looking-time study, 24 infants 6 months of age were presented with continuously folding and unfolding patterns of stripes. The luminances in the dynamic lightness constancy pattern were changed in such way that adults attribute them to changes of the various regions’ orientation relative to the light source (lightness constancy display). The “reversed” lightness constancy stimulus consisted of a continuously folding and unfolding pattern, in which the luminance changes were not consistent with a striped surface illuminated from one side. The only difference between the animations was the relationship between the change in surface orientation and the change of luminances. The infants looked significantly longer at the reversed lightness constancy animation than at the lightness constancy display. This finding suggests that the infants detected the violation of the lightness constancy rules in the reversed lightness constancy stimulus. The infants were also presented with control animations to rule out the possibility that looking preferences were based on low-level properties of the display.

► Infants 6 months of age were tested for their ability to extract lightness constancy.
► The stimuli were animations displaying continuously folding and unfolding patterns of stripes.
► Combination of surface 3D orientation change with gray level change was manipulated.
► The infants detected the combination which violated the lightness constancy rules.
► Control animations ruled out that the results were determined by low-level attributes.