A Review of Bokslag (1960)
A Review of the Bokslag (1960) study on the validity of the Wartegg in a selection setting Jarna Soilevuo Grønnerød
Bokslag, J.G.H. (1960) De predictieve waarde van de teken-test van Wartegg (W.Z.T.) en van een verrichtingstest (Block Design uit Wechsler-Bellevue-Scale) bij de selectie van leerjongens voor drie bedrijven. [The predictive value of the Wartegg drawing test and of a performance test (Wechsler Block Design) in the selection of apprentices for three industrial plants.] Nederlandsch Tijdschrift voor Psychologie 15, 321--33. In three different industrial companies, the job performance of 96 male apprentices between 14 and 18 years of age, most of which had completed public vocational school and got a lower technical school diploma, was evaluated by directors of human resources. The subjects were classified into five groups according to their suitability for their work: very suitable (15), suitable (21), average (31), less suitable (20) and unsuitable (9). In order to measure psychological characteristics like intelligence, psychic energy, emotionality and certain behaviours, the author developed a WZT scoring system of 22 variables, including pencil pressure, straight, round and angular forms, dynamic or static contents and the sentiment of the drawing. The presence or strength of each feature was evaluated on a scale from 0 to 3. The Wartegg manuals by Ehrig Wartegg and G. Marian Kinget were used as sources. The classification of the subjects into the five categories mentioned above based on the Wartegg results had an average correlation of r = 0,49 with the human resouces directors' evaluations. In addition, a separate Wartegg carefulness score was developed from variables measuring the abilities of carefulness, structured working style and spatial perception in order to compare the test results to the managers' evalutations of the apprentices' carefulness in their work. This correlation was even higher, r = 0,65, while the WZT carefulness score correlated r = 0,58 with the overall managers' evaluation. In addition to the Wartegg and the managers' evaluations, psychologists' evaluations and Block Design was also used, thus making the overall study design comprehensive.
The results which were coded in the meta-analysis by Soilevuo Grønnerød and Grønnerød (2011) were the following: Variables -> correlation
Psychologists' evaluation – WZT classification -> 0,48 Psychologists' evaluation – WZT total score -> 0,40 Psychologists' evaluation – WZT carefulness score -> 0,48 WZT classification – Block Design -> 0,32 WZT classification – employers' classification -> 0,49 WZT total score – Block Design -> 0,33 WZT total score – employers' classification -> 0,43 WZT carefulness score – Block Design -> 0,39 WZT carefulness score – employers' carefulness evaluation -> 0,65 WZT carefulness score – employers' classification -> 0,58 The author concludes that in the long run the Wartegg may prove to be a useful tool in selection, but the projective element in the method seems to bother the author. The author maintains that he took a certain distance to the projective element of the method in the descriptive assessment when the subjects were divided into the five categories. In the Wartegg total score, out of which the Wartegg carefulness score was extracted, the projective element was included. However, there does not seem to be noticeable differences in the results between the WZT classifications and the WZT total score/carefulness scores. Nevertheless, the tension between the symbolic/projective systems of test interpretion and the analytic traditions focusing on perception and the visual characteristics of the method is still unresolved.
