Monday, 11 January 2010

Summary: Grassman and Tomasello (2010)

Grassman and Tomasello recently published a study in reaction to Jaswal & Hansen (2006). Jaswal & Hansen found that children ignore pragmatic cues (pointing and looking at objects) in favour of honouring mutual exclusivity. In the first experiment, 24 children (3-4 y.o) were presented with a novel and a familiar item (see my post on diagrams). They were split into two conditions where the experimenter pointed at the familiar object and either asked 'Can you hand me the X?', where X was a novel noun, or made a neutral request ('Can you give it to me?').

All children in the latter 'pragmatic baseline' condition selected the familiar object the experimenter was pointing or looking at, while almost all children selected the novel object when presented with a novel noun. In a second experiment, a similar setup was used, but where the experimenter shifted their gaze towards one object instead of pointing and used an arbitrary label which could refer to any of the objects (e.g. 'Can you give me the one I got yesterday?') instead of the neutral . Here, children presented with a novel label chose the familiar item significantly less often than those in the pragmatic baseline.

The children were aware of the pragmatic cues: Children in both conditions monitored the experimenter's cue equally often. Furthermore, Jaswal & Hansen report that some children, when asked for a novel noun and presented with a pragmatic cue (looking at the familiar object), checked under the table on the side suggested by the pragmatic cue then selected the novel object anyway.

However, Grassman & Tomasello (2010) question Jaswal and Hansen's conclusions, pointing out that gestural cues are ontogenetically and phylogenetically primary to conventional, linguistic cues.

Furthermore, they argue that Jaswal & Hansen's pragmatic cues were non-ostensive. That is, the experimenter's gaze did not follow the pointing or, in the looking condition, there was no gaze alternation. Thus, there was no cue that the pointing/looking was a communicative act intended for the child. Furthermore, they used 'small' pointing, which is associated with redundant information rather than instead of 'big' pointing which is associated with primary information.

Grassmann & Tomasello extend Jaswal & Hansen's experiments with direct linguistic cues ('Give me the X', where X was a novel noun) instead of indirect ('Give it to me'). Two and four year olds showed no preference for linguistic over non-ostensive cues. However, without pragmatic cues, children chose the the novel object, while with ostensive cues (pointing with whole arm, gaze alternation) children chose the familiar object (see my post on diagrams). These directly oppose Jaswal and Hansen's results.

In a second experiment, children were presented with a familiar and novel object and requested a the familiar object verbally while pragmatically cuing the novel item. Children chose the novel object, following the pragmatic cue.

In a third experiment, the experimenter presented two familiar objects while verbally requesting one and pragmatically cuing another. Here, there were no preferences for following the pragmatic or lexical cue. 2 year olds exhibited mixed responses across trials, while 4 year olds were consistent, but with half following the pragmatic cue and half following the lexical cue.

Grassmann & Tomasello place this data in the context of the child's conflict resolution and lexical entries. Children try to integrate cues from different domains into one coherent communicative intention. It is suggested that it may be harder to modify lexical entries for familiar words without a clear reason than to link novel words to familiar objects.

Jaswal VK, & Hansen MB (2006). Learning words: children disregard some pragmatic information that conflicts with mutual exclusivity. Developmental science, 9 (2), 158-65 PMID: 16472316

Grassmann, S., & Tomasello, M. (2010). Young children follow pointing over words in interpreting acts of reference Developmental Science, 13 (1), 252-263 DOI: 10.1111/j.1467-7687.2009.00871.x

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