THE DEVELOPMENT OF EXECUTIVE FUNCTION IN EARLY ...

This version required children to remember which test cards to sort by shape and which test cards to sort by
color. Moreover, as in the standard version, children were asked to switch from sorting by one dimension to
sorting by the other. However, as in the 2+2-Rules (unidimensional) version, there was no conflict among the
rules, so, according to CCC theory, no higher order rule was required. As predicted by CCC theory, most
children performed well on this version.
Experiment 3 addressed the question of memory demand in a different way. In this experiment, children were
given a new 4-Rules version, called the 4-Rules (superordinate) version, that required using four superordinate
rules (described functionally: things that can walk, things one can wear, things one can ride, and things one can
eat) to sort a heterogeneous series of items (e.g., a jacket, a truck, a fried egg). It was expected that the memory
demand in the 4-Rules (superordinate) version would be even greater than that in the 4-Rules versions used in
Experiments 1 and 2 because in the 4-Rules (superordinate) version children not only needed to keep four
superordinate distinctions in mind, but they also need to determine which rule applied to each test card (i.e.,
there were storage plus processing demands). Nonetheless, because there was no conflict among the rules, this
new version was expected to be relatively easy for 3- to 4-year-olds. As predicted, children performed better on
the 4-Rules (superordinate) version than they did on the standard version of the DCCS. Clearly, children's
difficulty with the standard version cannot be attributed in any straightforward way to a constraint on memory
capacity. Instead, children seem to have difficulty when required to select among conflicting rules.
EXPERIMENT 1
Experiment 1 was designed to assess the possibility that 3- to 4-year-olds fail the postswitch phase because they
simply cannot keep the postswitch rules in mind. Two new versions of the DCCS were created: a 4-Rules
(unidimensional) version and a 2+2-Rules (unidimensional) version (see Figure 6). The new versions were
similar to the standard version in that the same number of rules was presented to children (four rules in total)
but different from the standard version insofar as there was no conflict among the rules.
In the 4-Rules (unidimensional) version, children were told four rules and required to use them to sort a series
of test cards by one dimension (e.g., color: "If it's blue it goes here, if it's orange it goes here, if it's white it goes
here, and if it's brown it goes here."). The 2+2-Rules (unidimensional) version was identical to the 4-Rules
(unidimensional) version in all respects except that, although children were told four rules, they were only
required to use two at a time, as in the standard version. This feature of the procedure was designed to
correspond to the fact that in the standard version children first used one pair of rules and then used another, in a
serial fashion.
If children's difficulty with the standard version of the DCCS is one of limited memory capacity, then children
should perform poorly on all three versions used in this experiment. However, if children's difficulty consists in
using higher order rules, then they should fail only on the standard version, in which the two pairs of rules are in
conflict.
Method
Participants and design. The sample comprised forty-one 3- to 4-yearolds (M = 42.2 months, range: 33 to 48
months; 20 girls and 21 boys). Four additional children were tested but excluded from the final sample, either
because of experimenter error (n = 1), refusal to complete the experiment (n = 2), or information from their
daycare supervisor that the child was developmentally delayed (n = 1). Children were of mixed socioeconomic
and ethnic backgrounds, although this information was not systematically collected.
As in all of the experiments to be described, children were recruited from local daycare centers or from a
database containing the names of parents who had expressed an interest in participating in research. Parents
were provided with a written description of the experiment, and they granted informed consent allowing their
children to participate.