How can we test whether someone is able to ascribe beliefs to others?
Here is one quite famous way to test this, perhaps some of you are even aware of it
already.
Let's suppose I am the experimenter and you are the subjects.
First I tell you a story ...
In a standard \textit{false belief task}, `[t]he subject is aware that he/she and
another person [Maxi] witness a certain state of affairs x. Then, in the absence of
the other person the subject witnesses an unexpected change in the state of affairs
from x to y' \citep[p.\ 106]{Wimmer:1983dz}. The task is designed to measure the
subject's sensitivity to the probability that Maxi will falsely believe x to obtain.
Recall the experiment that got us started.
These experimenters added an anticipation prompt and measured to which box subjects looked first (Clements \& Perner, 1994).
(Actually they didn't use this story; theirs was about a mouse called Sam and some cheese, but the differences needn't concern us.)
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What got me hooked philosophical psychology,
and on philosophical issues in the development of mindreading in particular
was a brilliant finding by Wendy Clements who was Josef Perner's phd student.
These findings were carefully confirmed (Clements, Rustin, \& McCallum, 2000; Garnham \& Ruffman, 2001; Ruffman, Garnham, Import, \& Connolly, 2001).
Around 2000 there were a variety of findings pointing in the direction of a confict between different measures.
These included studies on word learning (Carpenter, Call, \& Tomasello, 2002; Happé \& Loth, 2002) and false denials (Polak \& Harris, 1999).
But relatively few people were interested until ...
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Control experiment:
‘In experiment 3, the adult was ignorant about which of the two locations held her toy.’
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There are some problems with replicating some of the studies which provide
evidence for infant mindreading, as many of you are probably already aware.
(Here’s a fragment of a spreadsheet created by Louisa Kulka and Hannes Rakoczy.)
One response to these difficulties with replication would be to say we just cannot
theories about infants until it has been cleared up.
For my part, I think the replication issue is super significant and the fallout is likely
to be illuminating.
But I also note that plenty of infant mindreading studies have been successfully replicated. So while
we should be cautious about details (and in particular about any one type of measure or scenario),
my sense is that there is clearly an interaction between measures of mindreading and age.