Motor Representation in Object Cognition
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Cardellicchio, Sinigaglia & Costantini, 2011 figure 1
Thinks about how adults represent objects.
For adults, it is not just a matter of knowledge and object indexes.
Objects are also represented motorically.
But how an object is represented motorically depends on its affordances.
And representing an object motorically generally depends on its being one you
could interact with.
Cardellicchio, Sinigaglia & Costantini, 2011 figure 2
[skip --- only included in case need for discussion]
Costantini et al, 2010 figure 1B
Importantly, putting a barrier between you and an object means that
you can’t interact with it, and so the object is unlikely to be
represented motorically.
And note that it doesn’t matter whether the barrier is an occluder; even a translucent
barrier will prevent objects being represented motorically.
Costantini et al, 2010 figure 1B
[skip --- only included in case need for discussion]
McCurry et al 2009, figure 1 (part)
Perfect way to deconfound barrier and occlusion: a screen
you can’t see through but can reach through.
Irony: McCurry et al call their paper ‘beyond the search barrier’.
But the whole point of an experiment like this should have been to
deconfound occluders and barriers (one blocks vision, the other
prevents action).
McCurry et al 2009, figure 1
Now consider an experiment with 5-month-olds using an occluder that is no
barrier to ation.
Instead the occluder is a fringed screen through which you can reach.
Here's the authors' description of their procedure.
'Once the ball came to rest at the right edge of the platform, the platform was pushed forward
until the edge of the platform was directly in front of, and within easy reach of, the infant. In
the second phase, the infant was allowed to search for 20 s. ' (McCurry, Wilcox, & Woods, 2009)
McCurry et al found that 5 month old infants reach towards the cloth screen more often
when a cube goes in and a ball comes out than when a cube goes in and a cube comes
out. (I.e. cube-ball vs cube-cube.)
Why? On the CLSTX conjecture, this makes no sense.
As we saw, a signature limit of object indexes is their disregard for featural
information. Further, object indexes don’t enable you to initate purposive actions.
So the CLSTX conjecture provides two reasons for making the incorrect prediction
that infants will not search longer in the cube-ball condition than in the ball-ball
condition.
But if you think about it in terms of motor representations, it makes perfect sense.
Here is an occluder that is no barrier for action, so no obstacle to representing
the objects motorically.
And of course motor processes care deeply about the shapes of things, so we should
expect a difference between the ball and the cube.
McCurry et al designed the perfect experiment to show that the CLSTX conjecture is not
the whole story, and that 5-month-olds can represent unperceived objects motorically.
But I don’t want to make too much of this because I’m interpreting their findings post
hoc.
Unfortunately this is not at all how they interpret their work.
Instead, they write that ‘when task demands are minimal (successful performance
requires only a direct reach through the fringe) young infants search reliably for
hidden objects.’
But I don’t think anyone who has carefully considered Shinskey and Munakata’s work
could be convinced by this idea.
It’s a shame they weren’t thinking in terms of the Crude Picture of the Mind,
but, you know, tant pis.
[skip]
What should we predict?
Cloth screen does not prevent action,\footnote{
‘In the first familiarization trial, infants were shown the fringed-screen and were encouraged to
reach through the fringe. If necessary, the experimenter gently guided the infant’s hand through
the fringed-screen. Once the infant placed his or her hand through the fringed-screen twice, the
trial ended.’
}
so reaching should be possible.
Further, if motor representations are responsible for the effect, the fact that
the experiment requires sensitivity to featural information should not be an issue.
(Further, a version of this task using violation of expectations may fail
because featural information is critical.)
And although these are very far from the terms in which they interpret their findings,
this is exactly what McCurry et al 2009 found.
McCurry et al 2009, figure 2