Representation of object orientation in children: Evidence from mirror-image confusions

Abstract

Although many cognitive functions require information about the orientations of objects, little is known about representation or processing of object orientation. Mirror-image confusion provides a potential clue. This phenomenon is typically characterized as a tendency to confuse images related by left–right reflection (reflection across an extrinsic vertical axis). However, in most previous studies the stimuli were inadequate for identifying a specific mirror-image (or other) relationship as the cause of the observed confusions. Using stimuli constructed to resolve this problem, Gregory and McCloskey (2010) found that adults’ errors were primarily reflections across an object axis, and not left–right reflections. The present study demonstrates that young children's orientation errors include both object–axis reflections and left–right reflections. We argue that children and adults represent object orientation in the same coordinate-system format (McCloskey, 2009), with orientation errors resulting from difficulty encoding or retaining one (adults) or two (children) specific components of the posited representations.

Keywords:

• Development
• Mirror images
• Object representation
• Orientation
• Spatial cognition

Acknowledgements

This work was supported by NINDS R01-NS050876 01A1 and an NSF IGERT grant. We thank Whitney Street and Sam Nastase for their help in collecting, coding, and analysing data.

Notes

¹Although the COR hypothesis can be applied to three- as well as two-dimensional objects and reference frames, we limit our discussion to two-dimensional representations because these are the representations relevant to our experiments.

²Previous discussions of COR simply assumed that one end of each axis was designated positive (+), and the other negative (–). However, this assumption leaves unanswered a question that turns out to be important in exploring the causes of some orientation errors: On what bases are polarity representations assigned to the ends of axes? The modified assumptions about polarity representations presented here are aimed at addressing this question.

³The COR hypothesis assumes that orientation representations include a parameter specifying which object axes are represented in relation to which extrinsic axes (McCloskey et al., 2006). However, this parameter of the posited representations is not central to the issues addressed in the present paper.

⁴This interpretation may appear to conflict with findings showing that even very young children can succeed at tasks requiring them to encode and retain left–right distinctions (e.g., Acredolo, 1978; Hermer & Spelke, 1994). For example, in reorientation tasks (e.g., Hermer & Spelke, 1994; Lee & Spelke, 2008), young children succeed in limiting their search for a hidden object to room corners with the appropriate left–right relationship between short and long walls (e.g., short wall on the left, long wall on the right). However, success in these tasks is defined as above-chance performance, and the results typically show that young children, despite performing at levels well above chance, are by no means perfect. For example, Lee and Spelke (2008) found that 4-year-olds searched in a geometrically inappropriate corner (i.e., a corner with the wrong left–right relationship between short and long walls) on 22% of trials in a standard reorientation task (vs. 0% geometrically inappropriate searches for adults tested under comparable conditions in Hermer & Spelke, 1994). In our experiments, children were similarly imperfect yet far above chance in distinguishing target orientations from extrinsic vertical axis reflections; collapsing across experiments EVA errors, although more frequent than most other error types, occurred in only about 10% of the trials.