which measured penile volume changes... to distinguish heterosexual and homosexual males for the Czechoslovakian army." When he escaped Europe for Canada, Freund was able to pursue his research using phallometry for the assessment of sexual offenders. At that time, attempts to develop methods of changing homosexual men into heterosexual men were being made by many sexologists, including John Bancroft, Albert Ellis, and William Masters of the Masters and Johnson Institute. Because phallometry showed that such methods were failures, Freund was among the first sexologists to declare that such attempts were unethical. Based primarily on Freund's studies, decriminalization of homosexuality took place in Czechoslovakia in 1961. (See also LGBT rights in the Czech Republic.) Reliability and validity In 1994, the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) of the American Psychiatric Association stated that penile plethysmography has been used in research settings to assess various paraphilias by measuring an individual's sexual arousal in response to visual and auditory stimuli. The reliability and validity of this procedure in clinical assessment have not been well established, and clinical experience suggests that subjects can simulate response by manipulating mental images." In contrast, a recent meta-analysis provides support for the validity of phallometric testing as a measure of sexual interests in children across 37 samples and 6,785 individuals. In 1998, Hanson and Bussière published a comprehensive meta-analysis of 61 scientific reports on the prediction of sexual offenses spanning more than 40,000 individual cases. They ascertained that of all the methods attempted and reported, penile phethysmographic responses to imagery depicting children was the single most accurate predictor of sexual re-offense across 7 studies reporting data from phallometric testing. Another meta-analysis in 2005 of 13 studies and 2,180 individual cases repeated the finding that phallometric responses to children was a strong predictor of sexual re-offense. A more recent meta-analysis that included 16 samples and 2,709 sexual offenders replicated and extended the previous findings that phallometric responding to children is a predictor of sexual re-offence. This meta-analysis extended previous meta-analytic research by showing phallometric responding to both male and female pedophilic and hebephilic stimuli predict sexual re-offence. Further, this meta-analysis showed that phallometric testing predicts sexual re-offence in distinct subgroups of sexual offenders against children. Critique of methodological problems There are criticisms of the methodology used to determine the reliability and specificity of penile plethysmography. One such criticism is that while penile plethysmography is said to be important for being more objective than a test subject’s subjective reports on sexual arousal, the argument for penile plethysmography being a more reliable gauge of sexual arousal than vaginal plethysmography is still that there is a higher correspondence on average between what the test subjects report and what the instruments observe in male subjects than in female subjects. There is a criticism of this discrepancy for lacking consistency in the standards of whether or not subjective reports are useful. There is also criticism regarding the possibility of sampling bias being greater in male subjects of penile plethysmography than in female subjects of vaginal plethysmography, males being generally more aware of their physical sexual responses than females in most cultures may cause the male volunteers to be almost exclusively individuals who have category specific erections due to those with nonspecific erections fearing erection in taboo contexts and therefore not signing up for the studies. This effect may explain apparent male specificity as a result of methodological bias. The difference between tests of volunteers and tests of convicted or suspected sex offenders in penile plethysmography results may be caused by the sex offender group often effectively lacking the choice not to