Aligning body and world: Stable reference frames improve young children’s search for hidden objects

Abstract

This study investigated how young children's increasingly flexible use of spatial reference frames enables accurate search for hidden objects by using a task that 3-year-olds have been shown to perform with great accuracy and 2-year-olds have been shown to perform inaccurately. Children watched as an object was rolled down a ramp, behind a panel of doors, and stopped at a barrier visible above the doors. In two experiments, we gave 2 and 2.5-year-olds a strong reference frame by increasing the relative salience and stability of the barrier. In Experiment 1, 2.5-year-olds performed at above-chance levels with the more salient barrier. In Experiment 2, we highlighted the stability of the barrier (or ramp) by maximizing the spatial extent of each reference frame across the first four training trials. Children given a stable barrier (and moving ramp) during these initial trials performed at above-chance levels, and significantly better than children given a stable ramp (and moving barrier). This work highlights that factors central to spatial cognition and motor planning-aligning egocentric and object-centered reference frames-play a role in the ramp task during this transitional phase in development.Recent studies have revealed something quite striking: older children sometimes fail to show competencies that infants have been thought to have. For example, researchers presented 2-and 3-year-old children with a ball that rolled down a ramp (Berthier, DeBlois, Poirier, Novak, & Clifton, 2000). The ball went behind an occluder with four doors and stopped at a barrier, visible above the occluder. The barrier could be placed beside any of the doors. Berthier and colleagues (2000) found that 2-and 2.5-year-old children were not able to select the correct door when asked to find the ball in this "ramp task." In fact, out of 16 2.5-year-olds, only 3 performed at above-chance levels. Three-year-olds were able to reliably choose the correct door at above-chance levels. This is surprising because infants in a related violation-of-expectancy task appear to understand that solid objects behind an occluder stop at solid barriers (see Spelke, Breinlinger, Macomber, Jacobson, 1992). We are left to wonder how can infants demonstrate an understanding of hidden objects and solid barriers while toddlers cannot.

Representational momentum in displacement tasks: Relative object weight matters in toddlers’ search behavior

“…To explore the potential origins of relative object weight in young children’s reasoning about object motion, Perry et al’s (2008) study seems most pertinent. Here, they employed an apparatus with a slope and barrier, and found that toddlers frequently searched for objects released down the slope in a location beyond the barrier; a finding also noted by various other studies employing the same apparatus or simplified versions of it (Berthier, DeBlois, Poirier, Novak, & Clifton, 2000; Butler, Berthier, & Clifton, 2002; Gresham, 2012; Hood, Carey, & Prasada, 2000; Keen et al, 2008; Kloos, Haddad, & Keen, 2006; Mash, Keen, & Berthier, 2003; Mash, Novak, Berthier, & Keen, 2006; Perry, Samuelson, & Spencer, 2009).…”

“…In line with other studies in the field examining relevant hidden displacement tasks using the same apparatus (cf. Berthier et al, 2000; Butler et al, 2002; Gresham, 2012; Keen et al, 2008; Kloos et al, 2006; Mash et al, 2003, 2006; Perry et al, 2008, 2009), toddlers’ search successes generally increased with age. Disregarding any differences between conditions, the youngest children in the present study merely performed at chance level as a whole, but by the age of 3 years they were already correct in around two-thirds of their searches.…”

To have and to hold: looking vs. touching in the study of categorization

“…However, failure can tell us something more interesting about development (Keen, 2003 ; Perry et al, 2008 , 2009 ). For example, Perry et al ( 2009 ) demonstrated changes in children's ability to align their body and movements with relevant spatial reference frames support search accuracy.…”

“…However, failure can tell us something more interesting about development (Keen, 2003 ; Perry et al, 2008 , 2009 ). For example, Perry et al ( 2009 ) demonstrated changes in children's ability to align their body and movements with relevant spatial reference frames support search accuracy. When 2-year-olds underwent training with the barrier in a fixed position while the ramp moved, such that the correct door was aligned with midline, they correctly located the object during the standard testing procedure.…”