Monday, 6 April 2009

Adults still challenged by Piagetian task

Jean Piaget, the celebrated Swiss psychologist who founded "genetic epistemology" - the study of how knowledge develops - believed that children's understanding of the world advances in discrete stages. Central to his theory was the idea that the stage a child is at can be revealed by the mistakes they make on key tasks. Now Gaelle Leroux and colleagues have scanned the brains of adults performing one of these tasks, and they've argued their results reveal evidence of child-like thinking in the adult brain.

The task they used is the so-called "conservation of number" task. Present a child younger than seven with two rows of items (buttons, for example) and ask them to say whether the two rows contain an equal number of items or not. You'll probably find that they base their answer on the length of the rows, regardless of the actual number of items in each row. The error reveals the child's use of an inappropriate "length=number" strategy.

When Leroux's team asked nine men to perform this task, they took longer to answer when the longer row wasn't necessarily the row with most items, compared with an easier condition, in which row length and number of items always matched. Moreover, the more difficult condition, involving length-number mismatches, was associated with increased activity in a swathe of brain areas compared with the easier condition. These regions included frontal regions such as the middle frontal gyrus and anterior cingulate cortex, which are known to be involved in inhibitory control.

The researchers said their findings show that the adults were having to inhibit a child-like tendency to follow the erroneous "length=number" strategy. They also noted that these frontal brain areas involved in inhibitory control are known to develop later in childhood than other areas which are associated with more basic functions. "These developmental findings support the idea of a crucial role of executive frontal areas in solving a task like Piaget's," they said, "as they mature precisely during a period when children become able to inhibit the perceptual bias - age 7."

ResearchBlogging.orgGaëlle Leroux, Jeanne Spiess, Laure Zago, Sandrine Rossi, Amélie Lubin, Marie-Renée Turbelin, Bernard Mazoyer, Nathalie Tzourio-Mazoyer, Olivier Houdé, Marc Joliot (2009). Adult brains don't fully overcome biases that lead to incorrect performance during cognitive development: an fMRI study in young adults completing a Piaget-like task. Developmental Science, 12 (2), 326-338 DOI: 10.1111/j.1467-7687.2008.00785.x

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.


Nestor L. Lopez-Duran PhD said...


An alternative interpretation is not that "adults were having to inhibit a child-like tendency to follow the erroneous "length=number" strategy", but that the adults were inhibiting "a heuristic" that is very common, useful, and likely adaptive as it accelerates speed of processing. Thus the results showing delayed reaction may reflect inhibitory control of an adaptive primary response, rather than a child-like error. In fact, the adults' correct but delayed responses may reflect the development of such inhibitory processes, which may explain why children have difficulty answering correctly. Did the authors discuss this possibility at all?

Digest said...

Hi Nestor
Thanks for your comments. Yes they certainly did discuss the role of inhibitory control and how this is probably lacking in young children. At one point in their introduction they did also refer to the length=number strategy as a heuristic: This strategy is an often-relevant quantification heuristic used by children, and still used by adults (Daurignac, Houdé & Jouvent, 2006; Houdé & Guichart, 2001; Leroux, Joliot, Dubal, Mazoyer, Tzourio-Mazoyer & Houdé, 2006). The tendency to rely on the length rather than on the numerical properties of a physical display when the two dimensions interfere as in the Piaget-like task is coherent with the view that numerical quantities are represented along a spatial mental 'number line' (Dehaene, Piazza, Pinel & Cohen, 2003; Dehaene & Cohen, 1995), which underlies the representation of spatial continuous dimensions (Cohen et al., 2005; Fias, Lammertyn, Reynvoet, Dupont & Orban, 2003; Pinel, Piazza, Le Bihan & Dehaene, 2004; Walsh, 2003).

Nestor L. Lopez-Duran PhD said...

Thanks for the reply. It seems then that the idea that adults are still being "challenged" by the task applies, in that the task is still difficult for them (but now doable). But the results suggest a different conceptualization of the original 'error' displayed by kids. While I'm sure this is likely old news to developmental cognitive scientist, it seems like the original error may not reflect a true deficiency in concept formation (length vs. quantity), but instead a deficiency in the capacity to inhibit an useful heuristic ("we can often infer quantity from length").

Winston said...

Seems to me (a non-expert) that the most likely explanation is that Piaget was wrong, to some degree at least. If the finding is surprising in the context of Piaget's prediction, then why is it being interpreted only in terms of Piaget's prediction.

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