Innate Ideas Revisited: For a Principle of Persistence in Infants' Physical Reasoning

Abstract

The notion of innate ideas has long been the subject of intense debate in the fields of philosophy and cognitive science. Over the past few decades, methodological advances have made it possible for developmental researchers to begin to examine what innate ideas-what innate concepts and principles-might contribute to infants ' knowledge acquisition in various core domains. This article focuses on the domain of physical reasoning and on Spelke's (1988, 1994) proposal that principles of continuity and cohesion guide infants' interpretation of physical events. The article reviews recent evidence that these two principles are in fact corollaries of a single and more powerful principle of persistence, which states that objects persist, as they are, in time and space.

Fig. 1

Decision trees representing two vectors relevant to occlusion events. A: Vector representing some of the variables infants identify as they learn when an object behind an occluder is hidden or visible. B: Vector representing some of the variables infants identify as they learn when an object that reappears from behind an occluder is the same object that disappeared or a different object. The ages in each vector represent the approximate ages at which the variables are identified.

Fig. 2

Schematic diagram of infants’ physical reasoning showing how infants represent and interpret the basic and variable information about a physical event. This hypothetical event involves two objects (Object 1 and Object 2). The layout component represents their spatial arrangement over time as the event unfolds.

Fig. 3

Examples of continuity violations involving occlusion events. A: At 2.5 months, infants are surprised if an object fails to become visible when passing between two screens placed a short distance apart (Aguiar & Baillargeon, 1999). B: Beginning at about 3 months, infants are surprised if an object fails to become visible when passing behind a screen whose lower edge is not continuous with the surface on which it rests, thus creating an opening between the screen and the surface (Aguiar & Baillargeon, 2002). C: Beginning at about 3.5 months, infants are surprised if a tall object fails to become visible when passing behind a short screen (Luo & Baillargeon, 2005). D: Beginning at about 7.5 months, infants are surprised when shown the following violation. Infants first see an object and a transparent occluder standing side-by-side. A large screen is raised to hide the display, and an experimenter’s gloved hand places the object behind the transparent occluder. The screen is then lowered to reveal the transparent occluder with no object visible behind it (Luo & Baillargeon, 2007).

Fig. 4

Examples of décalages in infants’ reasoning about the variable height in different event categories. Infants are surprised to see a tall object become almost fully hidden behind a short container (occlusion event) at 4.5 months, but they are not surprised to see a tall object become almost fully hidden inside a short container (containment event) until about 7.5 months (Hespos & Baillargeon, 2001). Infants are surprised to see a tall object become fully hidden under a short cover (covering event) at 12 months, but they are not surprised to see a tall object become fully hidden inside a short tube (tube event) until 14 months (Wang et al., 2005).

Fig. 5

Familiarization and test events shown in Wu et al. (2006). In the familiarization event, an experimenter’s gloved hand lifted a red column and a black ball in alternation above the center of a wide screen, between two small, closed windows. Each window could be opened by lifting a handle that protruded above the screen. In the expected test event, the hand opened the right window to reveal the column and then opened the left window to reveal the ball; this sequence was repeated until the trial ended. In the unexpected test event, the hand opened the right window to reveal the column and then again opened the right window to reveal the ball; this sequence was repeated until the trial ended.

Fig. 6

Test events shown in Ng et al. (2007). At the start of each event, a green cylinder with yellow dots stood on an apparatus floor to the right of a large opaque screen. An experimenter’s hand lifted the cylinder, moved it to the left, and then lowered it behind the center of the screen; at that point, the experimenter’s hand was no longer visible. After a pause, the hand brought out a similar green cylinder with either yellow stripes (pattern event) or red dots (color event) and then returned it behind the screen. Next, the hand brought out the yellow-dotted cylinder again. Finally, the screen was lowered to reveal a second, transparent screen; no cylinder stood behind this screen.