Each subject sat at a table, and was given a blank sheet of paper and a pen. The experim enter also sat at the table and produced the book of stimuli. The experim enter said "Now, we're going to do some
draw ing. I'm going to show you a picture, and in each case I w ant you to d raw exactly w h at you see." The first stim ulus w as shown, for five seconds, rem oved from sight and the subject then asked again "Draw exactly w hat you saw". W hen the subject finished that draw ing, their sheet w as rem oved and a new blank sheet given. The procedure was then repeated for the rest of the stimuli.
The d ra w in g s w ere th en scored by th e ex p erim en ter. Hierarchical stim uli draw ings and non-hierarchical stim uli draw ings w ere scored according to the relevant systems.
The experimental hypotheses are:
CONTROL SUBJECTS HYPOTHESES
for effect of global and local level
H I: h y p o th e sisi states that the m ean accuracy of reproduction of global and local elements will not significantly differ.
H I: h y p o th e siso states th at the m ean accuracy of reproduction of global and local elements will significantly differ.
fo r effect of age
H2: h y p o th esisi states that there will be a significant effect of age of subject on both the m ean accuracies of both global and local levels, both increasing w ith age, and w ith the difference betw een local and global levels, the local level m ean accuracy being greater w ith younger subjects.
H2: h y p o th esise states that there will be no significant effect of age of subject on both the m ean accuracies of both global and local levels, and the difference betw een local and global levels, the local level m ean accuracy being equal to the global level for all ages of subject.
HYPOTHESES FOR WILLIAMS SYNDROME SUBJECTS
A ssum ing that the results of Bellugi et al. (1988) are replicated, the following predictions can be made:
H3: h y p o th e sis! states that the m ean accuracy of reproduction of global and local elem ents will significantly differ, w ith local level accuracy being greater than global level accuracy. In addition, the m agnitude of this difference should be greater than that seen in any norm al controls.
H3: h y p o th e siso states th at the m ean accuracy of reproduction of global and local elements will not significantly differ.
A ssum ing that there is a significant effect of age on both level accuracies in the norm al control groups, then one m ay expect that the mean accuracies of both local and global levels in the WS group will be affected by their m ental age. The best m easure of this for this spatial task will be the Ravens Progressive Matrices task (Raven, 1986).
H4: hypothesis! states that there will be a significant correlation of both accuracy levels w ith the test age for the Ravens Progressive Matrices task.
H4: h y p o th esiso states that there will be no significant correlation of both accuracy levels w ith the test age for the Ravens Progressive Matrices task
R E S U L T S
H ierarchical d raw in g s w ere rated for global level (whole) accuracy and local level (parts) accuracy according to the scoring system described in the introduction. Scores for each level of accuracy for each draw in g ranged on a 6 point scale from 0 to 5, 5 being a perfect reproduction on that level.
Non-hierarchical draw ings were rated for accuracy according to the scoring system below:
Scoring system for non-hierarchical stimuli
This is a 4 p o in t scale, ranging from 0 to 3, 3 being a perfect reproduction.
Score 0
nothing or scribble
Score 1
Recognisable bu t inaccurate match. If target open, give credit for open. If target closed, give credit for closed.
Score 2
Good approxim ate match. May be orientation problems. May be slight curving of w hat should be rectalinear shapes.
Score 3
Excellent match.
Scores for each level of accuracy for each draw ing ranged on a 4 point scale from 0 to 3 ,3 being a perfect reproduction on that level.
NORMAL CONTROL SUBJECTS
N on-hierarchical stim uli
The m ean scores for subjects in each age group are as follows:
TABLE B.XVII
SCORES FOR N O RM A L C O N TRO L SUBTECTS W ITH N O N - HIERARCHICAL STIMULI 3 year olds MEAN M IN IM UM MAXIMUM 0.9/3 0 2 5 year olds MEAN M IN IM UM MAXIMUM 2.6/3 1 3
There is a significant effect of age of subject on reproduction of non-hierarchical stimuli, w ith older subjects being more accurate.
Hierarchical stimuli
The m ean scores for subjects in each age group are as follows: