Allen D. Calvin

Experimental Validation of Conditioned Inhibition

24 naive albino rats were run down a straight alley 30 trials a day. Half were fed 10 gm. per day and half 12. Half were run under spaced conditions and half under massed. All Ss stopped running although they were rewarded on every trial. Drive level was significantly related to days to extinction, and massing of trials was significantly related to running time. Implications of these findings were discussed.

The Enclosing Contour Effect

If a line-forms a closed, or almost closed, figure, we see no longer merely a line on a homogeneous background, bur a surface figure bounded by a line. This fact is so familiar that unfortunately it has, to my knowledge, never been made the subject of a special investigation. And yet it is a very startling facr, once we strip it of its familiarity. Therefore, we want a functional proof for our claim that a figure surrounded by contours is an entity different from the field outside the contours, which in all other respects produces the same stimulation. W e possess methods by which a difference betweex a contour figure and its surroundings could be established, but these methods have nor been applied to our problem. W e might measure the threshold of a small figure produced either inside or outside the contour of our original figure . . . . If then the litde figure required a greater episcotister opening in order to become visible inside than outside the contour, nfe should have proved a greater cohesiveness of the enclosed area as compared with its surroundings, which would make it more difficult to produce a new figure on it (Koffka, 1935, p. 150) .

THE ENCLOSING CONTOUR EFFECT: SOME ADDITIONAL REMARKS

W e would like to thank Professor Vernon (1961) for calling to our attention Craik and Zangwells study done in England in 1939. It is very interesting that in spite of the difference in instrumentation, which would be expected in two decades, the general experimental strategy and findings of the two studies are remarkably similar. It seems parricularly worthy of note that Gaik and Zangwell (1939) and the present writers, Youniss and Calvin ( 1961 ), hit on the notion of using parallel lines in their final experiments. Incidentally, we were curious as to how Professor Vernon happened to uncover this particular study when we had overlooked it. We, therefore, returned to the abstracts and looked up the description of Craik and Zangwells paper. The abstract of that particular article was Professor Vernons. . .