Recently, Canter (a) has explored the efficiency of the Background Interference Procedure (BIP), a modified technique of the Bender-Gestalt Test, in differentiating organic from non-organic Ss. This technique requires Ss to draw the Bender designs twice: Once on a blank paper and once on a paper with a confusing array of intersecting lines (BIP). He hypothesized that in comparison to non-organics, organic Ss would show a worse performance under the BIP condition than under the standard condition. Using 30 organic psychiatric patients and 57 non-organic psychiatric patients, the results of Canter's study supported his hypothesis.
The primary characteristics of organic mental retardates are distractibility and inability to perceive a meaningful configuration under confusing background.
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With this theoretical framework, the present investigation replicates Canter's study with mental retardates. It was hypothesized that the drawings of the organic retardates under the standard and BIP conditions would differ more significantly than would the drawings of the non-organic retardates under the same two conditions. In order to be sure that the differences, if any, found between the organic and non-organic are due to organicity and not due to emotionality, emotionally disturbed non-organic retardates were introduced and a subsidiary hypothesis was stated : The drawings of the organic group under the two conditions would differ significantly more than would the drawings of the emotionally disturbed nonorganic group under the same two conditions. METHOD The Ss were inmates of Rosewood, Spring Grove, and Springfield State Hoe-