406 DR. J. C. MOTTRAM ON 



as it will fall naturally under one of the conditions ah*eady 

 considered. For instance, a. very light grey object may resemble 

 the light square of the checkered background, both in shape, size, 

 and position, as in text-fig. 15, 2 ; but it can also be considered 

 under the heading " Objects falling on one component of the 

 background." If it falls as in text-fig. 15, 5, then on two com- 

 ponents of background ; if as in no. 4, then as an object visible 

 after the pattern has blended at distance. 



It appears, therefore, that a direct i-esemblaiice does not 

 necessitate a sepai-ate consideration. 



Conclusions. — The factors which make for the conspicuousness 

 of plain objects against patterned backgrounds appear to be 

 similar to those when plain backgrounds are used. If the 

 pattern of the background interrupts the object's margin, then 

 outline blurring occurs. The near presence, or contact with 

 the object, of an area of tone similar to the object makes it less 

 visible. 



(D) Patterned Objects against Patterned Backgroimds. 



If a patterned object be viewed against a patterned background 

 from gradually increasing distances, several different appearances 

 may be seen. 



(1) The pattern of the object may blend before the pattern of 

 the background, in which case it will appear as a plain object 

 against a patterned background. 



(2) The pattern of the background may blend before the 

 pattern of the object. The object will then appear as a 

 patterned one against a plain background. 



(3) The patterns of object and background may both blend 

 and yet the object may still be visible against the background, 

 in which case the object will appear plain against a plain 

 background. 



These three conditions have already been dealt with. 



(4) A fourth appeai^ance may occur. The object may not be 

 visible, although neither its pattern nor the pattern of the 

 background have blended. 



Before dealing with this appearance the first three must be 

 briefly considered. It has already been shown in my previous 

 paper (loc. cit.) that though a patterned object is not less visible 

 than a plain one, nevertheless, if the pattern interrupts the 

 margin, then its outline after pattern-blending appears blurred 

 and indistinct, as compared with a plain object of the same tone 

 as the patterned one after blending. 



It has also been mentioned (p. 402) that outline blurring 

 similarly occurs when the object is plain and the background 

 patterned. It might therefore be concluded that against 

 patterned backgrounds the outline of a plain object would appear 

 just as blurred as that of a patterned one beyond the blending 

 distance of the background's pattern ; but when both the object's 



