THE DEVELOPMENT OF EXECUTIVE FUNCTION IN EARLY ...

observed in this experiment provides converging evidence that negative priming is only observed when there is
a conflicting mismatch between target and test cards during the preswitch phase, and, hence, when children
must select against a competing alternative.
Interpretation in terms of activation is less straightforward, and several possible interpretations exist. One
possibility is that activation of selected preswitch rules only occurs when there is conflict between target and
test cards during the preswitch phase. In Experiment 8, errors were observed in the Partial-Partial Change
versions. Although it was not possible during the preswitch phase to sort by the alternative rules (because values
of the alternative dimension were missing either for the target cards or the test cards), there was conflict
between target and test cards in the sense that target and test cards did not match. Another possibility is that
values of the irrelevant dimension were actually positively primed (i.e., more strongly activated) rather than
negatively primed. Positive priming of unattended values has been observed in some circumstances in the adult
literature on negative priming (e.g., Fox, 1995). These possibilities, along with others, will need to be explored
further.
GENERAL DISCUSSION
Experiment 8 replicated and extended the findings from Experiment 7 in the absence of feedback during the
preswitch trials. Whereas about half of the 3- to 4-year-olds perseverated in the Partial Change (no preswitch
feedback) version, nearly two-thirds passed the Total Change (no preswitch feedback) version. Experiment 8
also revealed that negative priming plays an important role in the DCCS. In the Negative Priming version, the
values of the dimension that was relevant during the preswitch phase were replaced by different values.
According to CCC theory and one reading of Kirkham et al.'s (in press) attentional inertia account, children
should have no difficulty with this version of the DCCS. However, 3- to 4-year-olds performed as poorly in the
Negative Priming version as they did in the standard version. Finally, in the Partial-Partial Change versions, the
values of the irrelevant dimension were removed during the preswitch phase on either the target cards or the test
cards. Performance on the Partial-Partial Change versions was nearly identical to performance on the Partial
Change version, raising the possibility that activation of the preswitch rules occurs even when it is not actually
possible to sort by an alternative rule.
Experiment 9 confirmed that 3- to 4-year-olds perform poorly on the Negative Priming version, and also
clarified the conditions under which negative priming occurs. Evidence indicates that negative priming occurs
only under conditions of conflict when it is possible to sort by values of another dimension. Negative priming
was not observed in the Negative Priming (redundant preswitch) version or the Redundant version, in both of
which target cards and test cards were identical during the preswitch phase. Both versions were significantly
easier than the Negative Priming version.
Experiments 8 and 9 suggest, therefore, that there must be a conflicting mismatch between target and test cards
during the preswitch phase in order for negative priming to occur in the DCCS. Under these circumstances,
suppression of the values of the interfering dimension persists into the postswitch trials, making it more difficult
to switch to sorting by the previously irrelevant dimension. These findings support the hypothesis that negative
priming occurs in the DCCS only when children must actively select the preswitch pair of rules against a
competing alternative.
Negative priming alone, however, does not suffice to explain 3- to 4-year-olds' performance on the DCCS. If
negative priming alone were operative, the children would have no difficulty with the Partial Change version, in
which the values of the dimension that was irrelevant during the preswitch phase were replaced by new values.
However, in both Experiments 7 and 8, about half of the children failed the Partial Change version, and
performance did not differ from the standard version in Experiment 7.
Thus, neither the negative priming hypothesis nor CCC theory can fully explain the pattern of findings.
Whereas the findings from the Partial Change version are consistent with CCC theory, the findings from the