The role of surface discontinuity and shape in 4-month-old infants' object segregation

Abstract

This research examined whether 4-month-old infants use a discontinuity in an object's front surface to visually segregate a display into two separate objects, and whether object shape enables its use. In Experiment 1, infants saw a three-dimensional display composed of two parts with distinctly different shapes. Two groups of infants saw a display in which these two shapes were divided by a visible discontinuity in the front surface (i.e., a boundary between the two objects). One of these groups saw the display move apart at the discontinuity when a gloved hand pulled one object; the second group saw the two objects move together as a single unit. A third group saw a modified version of this display that had no discontinuity present. The results suggested that infants regarded the discontinuity as an indication that the display could be composed of more than one object. In Experiment 2, infants saw the same display, but with a shape that did not highlight the discontinuity. The infants in this study showed no evidence of using the discontinuity. Together, the findings suggest that 4-month-old infants use the surface discontinuity between two objects as an indication that multiple objects could be present in a display, but only when scanning the outer edges of the display leads them to attend to it.

Keywords:

• Object segregation
• Object features
• Infant
• Perceptual development
• Cognitive development

Acknowledgements

This research was supported by a grant from the National Institute of Child Health and Human Development (FIRST grant HD-32129) to AN, and from the Eric Ormond Baker Charitable Fund to JK. We thank Stephanie DiGuiseppi, Erika Pond, Avani Modi, Scott Huettel, Cynthia Ramirez, Peter Goodin, and Susan Garland-Bengur for their help with the data collection and analyses, and Klaus Libertus for his help with the figures. We also thank the parents and infants who gave their time and effort to make this research possible.