disinclined to publish studies that lack clear findings. Thus, they are not submitted for publication or are rejected, and the published literature is, in effect, incomplete. This effect biases the literature in the direction of appearing to show stronger relationships than would otherwise be evident. If research funding agencies are suppressing research, the effects would be similar, though for a different reason. Studies that call the validity of polygraph testing into question, whether by failing to find accurate detection or by finding that accuracy is not robust across the range of situations in which polygraph tests are used, would fail to appear in literature searches.

We have not investigated the various allegations, so we are not in a position to evaluate the extent to which the alleged activities may have biased the literature. In Chapter 5 we do compare the polygraph accuracy estimates that come from studies with different sources of funding as a way of shedding some light on the possible effect of bias on the research literature, and find little difference. However, the distinctions between funding sources of these studies were often blurred.

Issues of conflict of interest reflect a serious structural problem with polygraph research. For the most part, the scientists involved in this area and the agencies involved in sponsoring and funding this research have a vested interest in supporting particular sets of conclusions about the reliability and validity of the polygraph (Levey, 1988). For example, U.S. agencies charged with initiating and sponsoring polygraph research (e.g., the U.S. Department of Defense Polygraph Institute) are also charged with the mission of training polygraph examiners and developing new polygraph applications. The dual mission of acting as a sponsor for polygraph research and as a sponsor for polygraph practice creates an obvious conflict of interest. Any reasonable investigator would anticipate that certain research questions (e.g., those that question the theory or logic of the polygraph) or certain patterns of results (e.g., those that suggest limited validity or strong susceptibility to countermeasures) will be less welcome by such research sponsors than empirical demonstrations that the polygraph “works.”

Because the great bulk of polygraph research has been funded by agencies that rely on the polygraph for law enforcement or counterintelligence purposes, there is a significant potential for bias and conflict of interest in polygraph research. Serious allegations suggest that this potential has at some times been realized. This possibility raises warnings that the entire body of research literature may have a bias toward claims of validity for the polygraph. Using a crude classification method (see Chapter 5), we did not see systematic differences in outcomes of polygraph validation studies between those conducted at or funded by polygraph-related agencies and those with a greater presumed degree of inde-

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