Developmental Science 10:4 (2007), pp 492–501 DOI: 10.1111/j.1467-7687.2007.00602.x © 2007 The Authors. Journal compilation © 2007 Blackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA. Blackwell Publishing Ltd PAPER The role of kinetic information in newborns’ perception of illusory contours Eloisa Valenza and Hermann Bulf Dipartimento di Psicologia dello Sviluppo e della Socializzazione, Università di Padova, Italy Abstract Previous research, in which static figures were used, showed that the ability to perceive illusory contours emerges around 7 months of age. However, recently, evidence has suggested that 2–3-month-old infants are able to perceive illusory contours when motion information is available (Johnson & Mason, 2002; Otsuka & Yamaguchi, 2003). The present study was aimed at investigating whether even newborns might perceive kinetic illusory contours when a motion easily detected by the immature newborn’s visual system (i.e. stroboscopic motion) is used. In Experiment 1, using a preference looking technique, newborns’ perception of kinetic illusory contours was explored using a Kanizsa figure in a static and in a kinetic display. The results showed that newborns manifest a preference for the illusory contours only in the kinetic, but not in the static, condition. In Experiment 2, using an habituation technique, newborns were habituated to a moving shape that was matched with the background in terms of random-texture-surface; thus the recovery of the shape was possible relying only on kinetic information. The results showed that infants manifested a novelty preference when presented with luminance-defined familiar and novel shapes. Altogether these findings provide evidence that motion enhances (Experiment 1) and sometimes is sufficient (Experiment 2) to induce newborns’ perception of illusory contours. Introduction When newborns first look at their surroundings, do they perceive a radically different world from older children and adults, or is their perceptual world organized in ways fundamentally similar to our own? Are newborns able to link together spatially separated contour frag- ments to build up the percept of a unitary shape? Which source of visible information is available to the immature newborn’s visual system to support this linking process? An attempt to answer all of these questions is to study how newborns perceive a shape against a background in the presence of illusory contours. Illusory contours, that are contours perceived in the absence of any physical gradient of change in the display (Kanizsa, 1979), can be used to study perceptual organ- ization precisely because the perception of a coherent form depends crucially on the relationship among the inducing elements. Therefore it is possible to create con- trol stimuli where the inducing elements are rearranged so as not to elicit perceptual grouping and consequently no perception of an illusory figure (Condry, Smith & Spelke, 2001). The best known example of illusory contours is provided by Kanizsa figures, in which in- complete circular elements induce the perception of a triangle or of a square. In these figures the illusory triangle (or square) is created by the careful positioning of inducing elements, which are themselves luminance- defined figures perceived as being partly occluded by the illusory edge. A contradictory framework regarding the onset of the ability to perceive illusory contours is provided by several developmental studies, aimed to investigate when illusory perception appears. Results from behavi- oural (Bertenthal, Campos & Haith, 1980; Condry et al., 2001; Csibra, 2001) and neurophysiological studies (Csibra, Davis, Spratling & Johnson, 2000) have demon- strated that illusory contours perception emerges around 7 months. However, several studies have provided evidence that 4-month-old infants and even younger babies perceive illusory contours (Treiber & Wilcox, 1980; Ghim, 1990; Address for correspondence: Eloisa Valenza, Dipartimento di Psicologia dello Sviluppo e della Socializzazione, via Venezia 8, 35131 Padova, Italy; e-mail: eloisa.valenza@unipd.it