What Is the Bogus Pipeline Effect?
The bogus pipeline (BPL) is a well-documented sociopsychological phenomenon in which individuals make more candid — and sometimes more incriminating — disclosures about themselves when they believe a device connected to them can detect their true knowledge, attitudes, or intentions, regardless of whether the device actually has this capability.
Origin
First documented by researchers Jones and Sigall (1971), the BPL effect was demonstrated when participants attached to what they believed was a sensitive physiological measuring instrument (an electromyograph) were significantly more willing to reveal socially undesirable attitudes than participants in control conditions.
Relevance to Polygraph Testing
The bogus pipeline concept is relevant to polygraph testing in two important and sometimes competing ways:
The Critic’s View
Some critics of polygraphy contend that the polygraph functions primarily as an elaborate bogus pipeline — that its true value lies not in genuine physiological detection of deception but in its power to elicit confessions and admissions through the examinee’s belief in the instrument. Under this view, the polygraph’s utility comes mainly from the psychological pressure it creates during the pre-test and post-test phases.
The Proponent’s View
Polygraph supporters counter that while the BPL effect may contribute to the overall utility of the examination process — and indeed, eliciting truthful disclosures is a valuable outcome — decades of controlled laboratory research demonstrate that the physiological data have genuine diagnostic value beyond any confession-eliciting effect. In laboratory studies where no post-test interview or interrogation takes place, trained examiners and automated algorithms still achieve accuracy rates well above chance based solely on the physiological recordings.
Practical Significance
Understanding the bogus pipeline concept helps explain why the complete polygraph examination process — including the pre-test interview, testing, and post-test phases — often produces valuable information even in cases where the physiological data alone might be inconclusive.
References
See: Jones & Sigall (1971).