THE DEVELOPMENT OF EXECUTIVE FUNCTION IN EARLY ...

(single test card), was included to assess any possible effects of using only a single test card, instead of the
usual two.
Method
Participants. Forty-eight 3- to 4-year-olds (M = 41.7 months; range: 35 to 52 months; 26 girls and 22 boys)
were recruited in the same fashion as in Experiment 1. An additional 6 children were excluded from the
final sample because of experimental error (n = 4), parental interference (n = 1), or refusal to complete the
experiment (n = 1).
Children were randomly assigned to receive one of three versions of the DCCS: the Pruned Tree (single test
card) version, the standard version, or the standard version (single test card). There were two sets of
cards, corresponding to two different pairs of dimensions. For set 1 (color and shape), the number of items
depicted on each test card was held constant. Target cards were (one) yellow car and (one) green flower, and
the test cards were (one) green car or (one) yellow flower. For set 2 (number and size), the shape of the items
was held constant (all items were rabbits). Target cards were one big thing (i.e., one big rabbit) and two little
things, and test cards were two big things and one little thing. Half of the children in each version received set
1 and half received set 2. Within each set, the particular dimension presented first was counterbalanced.
Procedure. The standard version was administered exactly as in the previous experiments, except that there
were 5 preswitch trials and 5 postswitch trials. Also, on the second demonstration trial, children themselves
were told to sort the test card (which was a different type of card than the card the experimenter sorted on the
first demonstration trial), and children were corrected if necessary on this demonstration trial. During test
trials, test cards were labeled by both dimensions.
The standard version (single test card) was identical to the standard version, except only one of the two
possible test cards was used on all pre-and postswitch trials. As a result, in the demonstration trials, both the
experimenter and the children sorted the same type of test card.
The Pruned Tree (single test card) version was administered like the standard version, except that children were
told a pair of rules that spanned two dimensions. For example, the task was introduced, the rules were
explained, and children who received the color and shape set (set 1) were shown the green car and told, "If it's
the green game put it here, but if it's the car game put it here." Then children were given two demonstration
trials, each illustrating one of the rules. On the first demonstration trial, the experimenter played the game that
was eventually required in the postswitch phase. On the second demonstration trial, children played the game
that was to be played in the preswitch phase. As in the two standard versions, there were 5 preswitch trials and
5 postswitch trials. On each trial, children were told the rules, shown a test card that was labeled by both
dimensions, told, "Play the (e.g., green) game," and asked, "Where does this go?" After the 5 preswitch trials,
children were told explicitly to switch to the new game. The total procedure took approximately 10 minutes to
administer.
Results
Group analyses. Performance was initially scored as the number of correct postswitch trials (out of 5). To
assess the effect of the particular dimension pair used (color and shape [set 1] vs. number and size [set 2]), a
two-way (Version x Dimension Pair) ANOVA was conducted. This analysis revealed no significant effects of
Dimension Pair and no Version x Dimension Pair interaction. This analysis was followed by a series of one-way
(Preswitch Dimension) ANOVAs that assessed whether the particular dimension (within each dimension pair)
that was used in the preswitch phase was related to postswitch performance. These analyses were run separately
for the children in the standard versions (who were told explicitly about both values of each dimension) and
children in the Pruned Tree version (who were only told explicitly about one level of each dimension). No
significant effects of preswitch dimension were revealed for either of the dimension pairs, except that children
in the standard versions scored better when number rather than size was the preswitch dimension, F(1, 14)
= 13.3,p