WORKING GROUP 1 
BIRNBAUM 
We will present the findings for this photo-mode study. The prime question 
is what difference, if any, is there in interpreter performance, that is attributable 
to photo-mode, i.e., to whether the interpreter views negative transparencies, 
positive transparencies, positive prints (non-stereo), or positive stereo prints. 
There are three analyses that were conducted: 1. An analysis of accuracy 
and completeness as a function of mode; 2. An analysis of confidence in right 
and wrong responses as a function of mode; and 3. An analysis of accuracy 
as a function of time separately for each mode. The sample consists of 64 photo 
interpreters with an average of five years experience. Four sets of photographs 
representing four different performance measures were used in this study. 
Table 1 describes these measures. The content of two of these is such that the 
desired identifications are individual objects. The scales of these photo sets 
are 1 : 5,700 and 1 : 8,000 respectively. The content of the remaining two sets 
consists of object complexes. The scale of both of these sets is 1 : 10,500. 
Table 1. Description of performance measures 
Each set of photographs consists of the same photograph reproduced in 
four modes: positive transparency, negative transparency, positive stereo prints, 
and positive non-stereo prints. Each of these was also reproduced at a lower 
quality level thus providing two photo qualities and making possible an analysis 
of mode-by-content-by-quality. 
In order to conduct our studies we must be able to measure interpreter 
performance. This requires the use of photographs the content of which is 
known to the researcher but, of course, not to the photo interpreter test subject. 
In addition, the photographs used and the requirements imposed on the inter 
preter should be as realistic as possible. Also, the interpreter is provided with 
relevant materials and information normally available to him, such as maps 
and specific information about the deployment of friendly and enemy forces, 
as well as equipment that is part of his photo interpretation kit. Essentially, 
then, the performance measure constitutes a work sample with a known input 
and with the opportunity for measuring interpreter output. 
The determination of what constitutes the content of a given photograph 
depends in all cases on the consensus of independent interpretations by expert 
interpreters. In addition, available records were studied to verify the basic ana 
lyses. In those rare instances when agreement could not be reached on the iden 
tification of a particular object, the object was scored neither right nor wrong. 
The performance indices used in these studies are a direct function of the 
nature of the responses the interpreter makes. The interpreter can correctly 
identify an object. The number of correct identifications (number of rights) 
Measure 
Content 
Scale 
1 
Individual Objects (e.gvehicles) 
1 : 5,700 
2 
Individual Objects (e.g., small structures) 
1 : 8,000 
3 
Object Complexes (e.g., R.R. yards) 
1 : 10,500 
4 
Object Complexes (e.g., fuel storage) 
1 : 10,500