U - Shaped Functions : Artifact or Hallmark of Development ?

Article: The articles in this collection consider one very interesting puzzle of development: U-shaped developmental functions. At some point during development, an organism might exhibit what seems like a regression from its expected developmental trajectory and, according to continuity models of development, this is aberrant. In this special issue, apparent regressions in behavior across a wide range of developmental phenomena are discussed. Gershkoff-Stowe and Thelen (this issue) present evidence that infants will reach correctly on B trials before they reach perseveratively, and that young children's naming errors actually increase with age before achieving a period of stability. Namy, Campbell. and Tomasello (this issue) show that even though 26-month-olds have difficulty with arbitrary gestures, younger and older children do not. Finally, Cashon and Cohen (this issue) show that the ability to integrate facial features follows a U-shaped developmental pattern for inverted faces. but oddly enough. an N-shaped pattern for upright faces. These counter-intuitive findings, and many others like them, seem to call for revisions to the common theoretical conception of development as a monotonically increasing. ever-improving process. In line with the contributors, our main thesis is that regressions in the developmental trajectory of particular behavioral traits are, if anything. the quintessential hallmark of the developmental process rather than mere artifacts of development.