Bem received a BA in physics from Reed College in Portland, Oregon in 1960 and began graduate work in physics at the Massachusetts Institute of Technology. The civil rights movement had just begun, and he became so intrigued with the changing attitudes toward desegregation in the American South that he decided to switch fields and pursue a career as a social psychologist specializing in attitudes and public opinion. He obtained his PhD in social psychology from the University of Michigan in 1964.
Bem taught at Carnegie Mellon University, Stanford, Harvard, and Cornell University. He started at Cornell in 1978 and retired in 2007, becoming a professor emeritus.
He testified before a subcommittee of the United States Senate on the psychological effects of police interrogation and served as an expert witness in court cases involving sex discrimination.
In 1972, Bem proposed the self-perception theory of attitude change, which proposes a different mechanism of change than that of Leon Festinger's cognitive dissonance theory. Although the two theories appear contradictory, evidence suggests that dissonance theory and self-perception theory each explain different aspects of how people adjust their attitudes and behaviors to one another. Dissonance theory explains how people change their attitudes when they find themselves acting in opposition to the attitudes they already hold, while self-perception theory explains how people create their attitudes in the first place.
According to self-perception theory, people infer their attitudes from their own behavior much as an outside observer might. For example, just as a person might watch someone else giving a pro-Fidel Castro speech and infer that the person is in favor of Castro, a person who is asked to give such a speech would consequently come to view him or herself as more in favor of Castro.
In 1970, Bem and Keith McConnell demonstrated that people are often unaware of attitude changes caused by their behavior. Instead, people believe that the views they currently hold are the views that they have always held. Bem and McConnell demonstrated this by measuring the change in Carnegie Mellon students' attitudes toward having control of their university curriculum. After an initial measurement of student attitudes, which were favorable toward student control, Bem and McConnel assigned students to write an essay opposing student control. By writing an essay proclaiming views different from the ones they held, students' views changed to become less favorable toward student control. When Bem and McConnell asked the students how they had felt at the beginning of the study, students insisted that they had always felt less favorable toward student control. The students believed that the experiment had not changed their opinions, even though it had changed their opinions significantly.
Bem's Exotic Becomes Erotic theory (EBE) presents one possible explanation as to what differentiates the etiology of homosexuality from heterosexuality. Bem theorized that the influence of biological factors on sexual orientation may be mediated by experiences in childhood, that the child's temperament predisposes the child to prefer certain activities over others. Bem noted that because of their temperament, which is influenced by biological variables such as genetic factors, some children will be attracted to activities that are commonly enjoyed by other children of the same gender, while others will prefer activities that are typical of the other gender. Bem theorized that this makes a gender-conforming child feel different from opposite-gender children, while gender-nonconforming children will feel different from children of their own gender. He believes that this feeling of difference evokes physiological arousal when the child is near members of the gender which the child considers as being "different". Bem theorizes that this physiological arousal is later transformed into sexual arousal: that is, as adults, people become sexually attracted to the gender which they came to see as different, or "exotic", while they were children.
Bem based this theory in part on the finding that a majority of gay men and lesbians report being gender-nonconforming during their childhood years. A meta-analysis of 48 studies showed childhood gender nonconformity to be the strongest predictor of a homosexual orientation for both men and women. Bem also noted that in a study by the Kinsey Institute of approximately 1000 gay men and lesbians (and a control group of 500 heterosexual men and women), 63% of both gay men and lesbians reported that they did not like activities typical of their sex in childhood, compared with only 10-15% of heterosexual men and women. Bem also drew from six prospective studies, longitudinal studies that began with gender-nonconforming boys around age 7 and followed them into adolescence and adulthood; a majority (63%) of the gender nonconforming boys become gay or bisexual as adults.
In parapsychology, Bem is known for his defense of the ganzfeld experiment as evidence of psi, more commonly known as extrasensory perception or psychic phenomena.
Bem and Charles Honorton (1994) reviewed the experimental arrangements of the autoganzfeld experiments, and pronounced them to provide excellent security against deception by subjects and sensory cues. However, Ray Hyman disagreed with Bem and Honorton as he had discovered some interesting patterns in the data that implied visual cues may have taken place in the experiments. Hyman wrote that the autoganzfeld experiments were flawed because they did not preclude the possibility of sensory leakage. Bem and Honorton's review was criticized by the scientific community as it contained errors. Julie Milton and Richard Wiseman (1999) who discovered errors in Bem's research carried out a meta-analysis of ganzfeld experiments in other laboratories. They found no psi effect, the results showed no effect greater than chance from a database of 30 experiments and a non-significant Stouffer Z of 0.70.
In 2011, Bem published the article "Feeling the Future: Experimental Evidence for Anomalous Retroactive Influences on Cognition and Affect" in the Journal of Personality and Social Psychology that offered statistical evidence for psi. The article's findings challenged modern scientific conceptions about the unidirectional nature of time. Its presentation by a respected researcher, and its publication by an upper-tier journal, engendered much controversy. In addition to criticism of the paper itself, the paper's publication prompted a wider debate on the validity of peer review process for allowing such a paper to be published. Bem appeared on MSNBC and The Colbert Report to discuss the experiment.
Wagenmakers et al. criticized Bem's statistical methodology, saying that he incorrectly provides one-sided p-value when he should have used a two-sided p-value. This could account for the marginally-significant results of his experiment. Bem and two statisticians subsequently published a rebuttal to this critique in the Journal of Personality and Social Psychology.
Jeffrey Rouder and Richard Morey, who applied a meta-analytical Bayes factor to Bem's data, concluded, "We remain unconvinced of the viability of ESP. There is no plausible mechanism for it, and it seems contradicted by well-substantiated theories in both physics and biology. Against this background, a change in odds of 40 is negligible.
After evaluating Bem's nine experiments, psychologist James Alcock said that he found metaphorical "dirty test tubes," or serious methodological flaws, such as changing the procedures partway through the experiments and combining results of tests with different chances of significance. It is unknown how many tests were actually performed, nor is there an explanation of how it was determined that participants had "settled down" after seeing erotic images. Alcock concludes that almost everything that could go wrong with Bem's experiments did go wrong. Bem's response to Alcock's critique appeared online at the Skeptical Inquirer website, and Alcock replied to these comments in a third article at the same website.
One of the nine experiments in Bem's study ("Retroactive Facilitation of Recall") was repeated by scientists Stuart Ritchie, Chris French, and Richard Wiseman. Their attempt to replicate was published in PLoS ONE and found no evidence of precognition. Several failed attempts by the authors to publish their replication attempt highlighted difficulties in publishing replications, attracting media attention over concerns of publication bias. The Journal of Personality and Social Psychology, Science Brevia and Psychological Science each rejected the paper on the grounds that it was a replication. A fourth journal, the British Journal of Psychology, refused the paper after reservations from one referee, later confirmed to be Bem himself, who "might possibly have a conflict of interest with respect to [the] ... submission." Wiseman set up a register to keep track of other replicating efforts to avoid problems with publication bias, and planned to conduct a meta-analysis on registered replication efforts.
An analysis by Gregory Francis in Psychonomic Bulletin & Review suggested that the number of rejections of the null hypothesis reported by Bem (eight out of nine experiments) is abnormally high, given the properties of the experiments and reported effect sizes. He calculated that the probability of Bem obtaining such results (0.058) is significantly less than the standard criterion used in tests of publication bias (0.1). According to Francis, this suggests that Bem's experiments cannot be taken as a proper scientific study, as critical data is likely unavailable. Francis also noted that Bem's experiments meet current standards of experimental psychology. Drawing on his own analysis and studies suggesting a discrepancy between the observed and expected null hypothesis rejection rates across the field of experimental psychology, he suggests that the standards and practices of the field are not functioning properly.
The publication of Bem's article and the resulting controversy prompted a wide-ranging commentary by Etienne LeBel and Kurt Peters. Using Bem's article as a case study, they discussed deficiencies in the accepted methodology most commonly used in experimental psychology. LeBel and Peters suggest that experimental psychology is systemically biased toward interpretations of data that favor the researcher's theory.
In 2012, the same journal that published Bem's original experiments, The Journal of Personality and Social Psychology (Vol. 103, No. 6), published "Correcting the Past: Failures to Replicate Psi" by Jeff Galek of Carnegie Mellon University, Robyn A. LeBoeuf of the University of Florida, Leif D. Nelson of the University of California at Berkeley, and Joseph P. Simmons of the University of Pennsylvania. The paper reported seven experiments testing for precognition that "found no evidence supporting its existence."
In a 2017 follow up article in slate magazine on the Feeling the Future Experiment Bem is quoted as saying. “I’m all for rigor, but I prefer other people do it. I see its importance—it’s fun for some people—but I don’t have the patience for it. If you looked at all my past experiments, they were always rhetorical devices. I gathered data to show how my point would be made. I used data as a point of persuasion, and I never really worried about, ‘Will this replicate or will this not?’ ”
Bem married Sandra Bem (née Lipsitz), also a psychology professor, in 1965. Though still legally married, they were "amicably separated" from 1994 until her death in 2014.