Thursday, 5 March 2015

The psychology of female serial killers

There is a mistaken cultural assumption, say Marissa Harrison and her colleagues, that women are, by their nature, incapable of being serial killers – defined here as murderers of three or more victims, spaced out with at least a week between killings.

This misconception, the psychologists warn, is a "deadly mistake". They point out that one in six serial killers are female. Their crimes tend to go undetected for longer than their male counterparts, likely in part because "our culture is in denial of women's proclivity for aggression."

Harrison and her team have profiled 64 US female serial killers active between the years 1821 to 2008. The researchers used the website to identify these killers and they verified the cases they found using reputable news sources.

The female serial killers had murdered between them at least 331 victims (making an average of 6 victims each). Their victims are of both sexes, but disproportionately male. The women had an average of age of 32 at the time of their first killing, and poisoning was the most common method. However, between them, the women used a range of murderous techniques, as the researchers explained:
"Contrary to preconceived notions about women being incapable of these extreme crimes, the women in our study poisoned, smothered, burned, choked, shot, bludgeoned, and shot newborns, children, elderly, and ill people as well as healthy adults; most often those who knew and likely trusted them."
Many of the homicidal women had stereotypically female professions, including being nurses and baby-sitters. They tended to be above average in physical attractiveness, which may have helped to engender trust in their victims.

As to motives, the most common was "hedonistic", a category in forensic psychology that refers to killing for financial gain, lust or thrill, with nearly half the sample fitting this category. The next most common motive was "power-seeking", which includes killing people in one's care.

The researchers urge caution regarding the factors that contributed to these women becoming serial killers. Apart from anything else, the historical records are incomplete and the absence of information does not mean that a given factor was not contributory. Nonetheless, Harrison and her team highlight several noticeable patterns in the data: a greater proportion of the women, as compared with the general population, had: a history of having been physically or sexually abused; drug or alcohol problems; and a diagnosis or signs of mental illness.

Quotes from some of the killers hint at their psychopathological thinking:
"They [the children] bothered me, so I decided to kill them."
"I like to attend funerals. I'm happy when someone is dying."
"That is my ambition, to have killed more people – more helpless people – than any man or woman who has ever lived."
A striking contrast with male serial killers is the relative absence of sexual violence and deviance. Two exceptions were a female serial killer who was a rapist, and another who reportedly barked like a dog during sex. But overall, the researchers highlighted how the women in their study primarily killed for resources, while their male counterparts kill for sex. This follows evolutionary theory, Harrison and her co-authors explained, in the sense that men are said to be motivated more by seeking multiple sexual opportunities, while women are motivated to find a committed partner with sufficient resources. "However," they added, "although an evolutionary framework can offer understanding, we stress that these heinous acts are a vicious extension of unconscious drives and are not therefore 'normal' or 'excused' ... ".

The new analysis points to a worrying trend: a 150 per cent increase in the number of reported cases of female serial killers since 1975. This study has obvious limitations, most obviously the reliance on historical records and news reports, and its exclusive focus on US killers. However, it makes a valuable contribution to a neglected topic.

The researchers concluded: "Increasing our understanding of serial killers may minimise the number of victims potentially lost in the future while maximising the effectiveness of interventions to prevent vulnerable individuals from taking a killing path."


Harrison, M., Murphy, E., Ho, L., Bowers, T., & Flaherty, C. (2015). Female serial killers in the United States: means, motives, and makings The Journal of Forensic Psychiatry & Psychology, 1-24 DOI: 10.1080/14789949.2015.1007516

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Wednesday, 4 March 2015

What use are flashbulb memories?

MJ Memorial at London's 02 Arena 
It could be the time you heard about the 9/11 terror attacks, or the moment you discovered that Michael Jackson had died. "Flashbulb memory" is the term psychologists use for when we remember the details of what we were doing and where we were when we heard dramatic news. What's the function of these memories, and is there any difference when the news is public or private, negative or positive?

Burcu Demiray and Alexandra Freund surveyed 565 US participants online about their memory of when they heard Michael Jackson had died and when they heard Osama Bin Laden had been killed. These were used as examples of a negative and positive flashbulb memory of a public event, respectively. For comparison, the participants were also quizzed about a time they heard that they, or a relative, had become pregnant, and a time they heard that a relative had fallen ill or passed away (a positive and negative private flashbulb memory, respectively).

In general, the flashbulb memories of receiving positive private news were "more important, consequential, emotionally intense, vivid, and frequently rehearsed" than the memories of hearing news about MJ's or Bin Laden's deaths. Moreover, participants said private flashbulb memories, positive and negative, played a more important role in supporting their stable sense of self over time, and in helping them solve current problems.

However, when it came to bonding with other people, it seems the the private /public distinction is not so important. For example, participants described memories of bad private news and memories of Michael Jackson's death serving similar social functions, in terms of building rapport with other people and getting to know them better.

Other details to emerge: positive flashbulb memories, private and public, were perceived as psychologically closer, as if they'd happened more recently; and older participants (middle-aged and up) said flashbulb memories are less important for facilitating self-identity over time and less important for social bonding.

Overall, it was those flashbulb memories that participants said were most significant to them (usually their memories of receiving private news), that were associated with more functions, such as for self-identity and bonding with other people. In contrast, the self-reported detail of memories was not associated with their having more function.

"This suggests," the researchers said, "that the functions of flashbulb memories are less about the shared societal reality and more about highly individual events shaping one's private life." This is an important finding for memory researchers because most studies on flashbulb memory have tended to focus on news of public events, such as the 9/11 attacks.

"Future research on the functions of flashbulb memories needs to focus more on individual, private memories," the researchers said. A limitation of their study, which they acknowledged, is that they uncovered people's beliefs about the function of flashbulb memories – it's possible the actual functions of these memories is different.

ResearchBlogging.orgDemiray, B., & Freund, A. (2015). Michael Jackson, Bin Laden and I: Functions of positive and negative, public and private flashbulb memories Memory, 23 (4), 487-506 DOI: 10.1080/09658211.2014.907428

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Tuesday, 3 March 2015

Visual illusions foster open-mindedness

From sworn witness accounts of alien visitations, to deep-rooted trust in quack medical treatments, the human trait that psychologists call "naive realism" has a lot to answer for. This is people's instinctive feeling that they perceive the world how it is, encapsulated by the saying "seeing is believing." The truth, of course, is that our every perception is our brain's best guess, built not merely with the raw material of what's out in the world, but just as much with the bricks of expectation, hope and imagination.

William Hart and his colleagues at the University of Alabama propose that naive realism not only inspires false confidence in what we see, but also more generally in our beliefs and assumptions. Based on this logic, the researchers tested whether explaining to people about naive realism, and showing them the unconscious, fallible mental work that leads to their unstable perceptions, might have knock-on effects, making them more open-minded and more doubtful of their assumptions about a person's character.

Nearly 200 students took part and were split into four groups. One group read about naive realism (e.g. "visual illusions provide a glimpse of how our brain twists reality without our intent or awareness") and then they experienced several well-known, powerful visual illusions (e.g. the Spinning Wheels, shown above, the Checker Shadow, and the Spinning Dancer), with the effects explained to them. The other groups either: just had the explanation but no experience of the illusions; or completed a difficult verbal intelligence test; or read about chimpanzees.

Afterwards, whatever their group, all the participants read four vignettes about four different people. These were written to be deliberately ambiguous about the protagonist's personality, which could be interpreted, depending on the vignette, as either assertive or hostile; risky or adventurous; agreeable or a push over; introverted or snobbish. There was also a quiz on the concept of naive realism.

The key finding is that after reading about naive realism and experiencing visual illusions, the participants were less certain of their personality judgments and more open to the alternative interpretation, as compared with the participants in the other groups. The participants who only read about naive realism, but didn't experience the illusions, showed just as much knowledge about naive realism, but their certainty in their understanding of the vignettes wasn't dented, and they remained as closed to alternative interpretations as the participants in the other comparison conditions.

"In sum," the researchers said, "exposing naive realism in an experiential way seems necessary to fuel greater doubt and openness."

At the time of writing, the internet is abuzz with talk of a dress that looks different colours to different people, with numerous scientific explanations on offer. It's a bit like the main intervention condition in this study writ large – experience of an illusion, combined with explanation that shows the hidden work of unconscious processing. Might this internet meme foster greater openness in society?

Before we get carried away, more is research is needed to test the longevity of these effects, and how far they generalise. It's possible, for example, that people's core beliefs would not be affected in the same way. Nonetheless, the researchers are hopeful: "... the present effects may have implications for fostering a more tolerant, open-minded society," they concluded.


Hart, W., Tullett, A., Shreves, W., & Fetterman, Z. (2015). Fueling doubt and openness: Experiencing the unconscious, constructed nature of perception induces uncertainty and openness to change Cognition, 137, 1-8 DOI: 10.1016/j.cognition.2014.12.003

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Monday, 2 March 2015

"I did it for the team" – How outsiders cheat in pursuit of popularity

If you would do anything to stay popular with your team-mates, what might follow? Bending the rules? Cheating? Sabotage of rivals? An international team led by Stefan Thau of INSEAD investigated “pro-group” unethical behaviours, and they suggest the people most likely to connive to boost the team are those at its margins, fearful of exclusion.

The experiment gave participants an easy opportunity to cheat at an anagram task, as the setup meant they themselves reported how many they solved, with no way to be checked. (Conveniently, the experimenters had an easy way to verify whether success had been over-reported: the ten anagrams were entirely unsolvable.)

In the key condition, participants were told that if they scored better than their “Red Team” competitor sitting in another room, then the other members of their own (Blue) team would all get a cash reward. The Blue Team had met and chatted at the start of the experiment, and just before the anagram task, they voted provisionally on which member should be excluded from a final group task, with a final vote to follow once the anagram contest results were made public.

The provisional vote was rigged so half of the participants had the impression that they were likely to be excluded. These at-risk individuals reported solving more of the impossible anagrams than their safe peers. They broke the rules to do a good turn for their group, in the hope that it wouldn’t go unrewarded. And the cheating was even higher for those participants who, in a questionnaire, described having a high “need to belong”.

In another condition, anagram victory generated a personal reward, not one shared with team-mates. Neither risk of exclusion nor the need to belong had any effect on cheating in this condition. This suggests that being under threat doesn’t simply increase unethical behaviour but encourages targeted actions aimed at raising standing.

Thau’s team showed that the effect generalised to other behaviours using a survey of 228 working adults. People who felt excluded – sharing heartbreaking beliefs such as  “I feel like it is likely that my workgroup members will not invite me for lunch” – were more likely to withhold information from non-team members or discredit another workgroup, all to make their own group look better.

Supporting your in-group in this way can only hurt the organisation in the longer-term, and can have profoundly damaging effects, such as the example the article gives, of a detective who framed people to get higher rates of arrest for his colleagues. There is no more chilling excuse for the inexcusable than “but I did it all for you!”


Thau, S., Derfler-Rozin, R., Pitesa, M., Mitchell, M., & Pillutla, M. (2015). Unethical for the sake of the group: Risk of social exclusion and pro-group unethical behavior. Journal of Applied Psychology, 100 (1), 98-113 DOI: 10.1037/a0036708

--further reading--
Are children from collectivist cultures more likely to say it's okay to lie for the group?

Post written by Alex Fradera (@alexfradera) for the BPS Research Digest.

Saturday, 28 February 2015

Link feast

Our pick of the best psychology and neuroscience links from the past week or so:

The Science of Why No One Agrees on the Colour of This Dress
The internet is abuzz with talk of the dress that some people see as white and gold, others as blue and black. Adam Rogers at WIRED provides an explanation.

Hard Feelings: Science’s Struggle to Define Emotions
"While it's possible for researchers to study facial expressions, brain patterns, behavior, and more," writes Julie Beck at The Atlantic, "each of these is only part of a more elusive whole".

Words and Sorcery
Simon Oxenham and Jon Sutton at The Psychologist consider the causes and consequences of bad writing in psychology.

Five Things Alice in Wonderland Reveals About the Brain
"All of us can learn something about ourselves from Alice in Wonderland – if only we look in the right way," says David Robson at BBC Future.

Do Blind People Really Experience Complete Darkness?
No. "For me," says Damon Rose at BBC News, who is completely blind, "dark has come to signify quiet, and because my built-in fireworks never go away I describe what I've got as a kind of visual tinnitus."

Why Are Men Committing Suicide?
"We are living in an epidemic of male suicide," writes Marc Judge at Acculturated.

The Elastic Brain
"A child’s brain can master anything from language to music," argues Rebecca Boyle at Aeon. "Can neuroscience extend that genius across the lifespan?"

Confessions Of A Disordered Eater
"After a lifetime struggling with compulsive, secretive, and restrictive eating, I’m still figuring out how to have a healthy relationship with food," says Anita Badejo at Buzzfeed.

Brain-controlled Drone Shown Off by Tekever in Lisbon
"... one aviation expert told the BBC he thought the industry would be unlikely to adopt such technology due to a perception of being potentially unsafe."

Why Reading and Writing on Paper Can be Better For Your Brain
"I can’t imagine teaching my son to read in a house without any physical books, pens or paper. But I can’t imagine denying him the limitless words and worlds a screen can bring to him either," says Tom Chatfield at The Guardian.
Post compiled by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Friday, 27 February 2015

What do clients think of psychotherapy that doesn't work?

Psychotherapy works for most people, but there's a sizeable group for whom it's ineffective, or worse still, harmful. A new study claims to be the first to systematically investigate what the experience of therapy is like for clients who show no improvement after therapy, or who actually deteriorate.

Andrzej Werbart and his colleagues conducted in-depth interviews with 20 non-improved clients (out of a larger client group of 134) who were enrolled in individual or group psychoanalytic psychotherapy at the former Institute of Psychotherapy in Stockholm. Seventeen of these clients showed no symptom improvement after an average of 22 months therapy, and three showed deterioration. The clients' had an average age of 22 at the treatment start, and 17 of them were female. Their problems included mood disorders, relationship problems and self-reported personality disorders. The interviews took place at the end of the course of therapy, and then again one and half years later.

The researchers transcribed the interviews and identified a key central theme: "spinning one's wheels" as exemplified by this client quote:
"When I think back on the therapy, I get the feeling that I often sat and talked; sometimes something important came up, but often it felt like it was pretty much just spinning my wheels."
What other messages were distilled from the interviews? The clients had largely positive views of their therapists, but they saw them as distant and not fully committed. A recurring issue for the clients was feelings of uncertainty over the goals of therapy and the methods to achieve those goals. Many had expected a more challenging, confrontational, structured style of therapy.

The researchers said the 16 therapists (10 female; average age 53), many of them highly experienced,  who'd worked with these non-improved clients, may have been guilty of sticking too rigidly to traditional psychoanalytic technique:
"The patients' descriptions of therapists' silence and passivity together with a focus on childhood experiences and deep roots of presented problems resemble a caricature of psychoanalytic psychotherapy, but unfortunately the picture may be accurate," they said.   
The researchers urged therapists to address their clients' treatment preferences and expectations – such reflection could have led to the realisation that a more "directive, task and action-oriented" form of therapy may have been more appropriate for these clients (conversely, other research has found that dissatisfied CBT clients tend to say they would prefer an approach with more emphasis on reflection and understanding). Clients need to be involved in setting the goals of therapy and educated about what the process will entail, the researchers added. But also, "the therapist needs to learn to be the unique patient's therapist."

Previous research has already established that therapists are poor at identifying when therapy is not working. Werbart and his team said that "formalised feedback" based on client surveys during therapy "can be a less threatening way to start discussions on negative and hindering therapy experiences."

On a positive note, between the end of therapy and later follow-up, more than half the non-improved clients showed beneficial decreases in their symptoms. Such ongoing change was not observed for clients who showed more immediate improvements after therapy, suggesting these changes were not a mere consequence of maturing. "Rather, the conclusion is that non improvement at [therapy] termination does not imply lasting symptoms," the researchers said.


Werbart, A., von Below, C., Brun, J., & Gunnarsdottir, H. (2014). “Spinning one's wheels”: Nonimproved patients view their psychotherapy Psychotherapy Research, 1-19 DOI: 10.1080/10503307.2014.989291

--further reading--
When therapy causes harm
The mistakes that lead therapists to infer psychotherapy was effective, when it wasn't
What clients think CBT will be like and how it really is

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Thursday, 26 February 2015

Some student-professor pairings lead to "unusually effective teaching" (and it's possible to predict which ones)

Video trailers can be used to predict which
lecturers are the best teachers, and which
students they are especially suited to.
In the near future, students could be presented with a series of video trailers of different professors at their university. Based on their ratings of these videos, the students will be paired with the professors who provide the best fit. The outcome will be superior learning, and greater student satisfaction.

That's the promise of a new study that asked 145 psychology undergrads to rate 6-minute teaching videos of 10 different professors, and then to rate their experience of an actual 40-minute live lecture with those same professors taken several weeks later. The students were also quizzed on the content of those lectures to see how well they'd learned.

Jennifer Gross and her colleagues explain that student evaluations of professors are made up of three key factors: each professor's actual ability (this component tends to correlate across ratings given by different students); each student's rating bias (this component correlates across the ratings given by the same student to different professors – for example, some students are more lenient in their ratings than others); and relationship effects.

This last component that is one of the key points of interest in the new study. It pertains to the specific fit, or not, between a professor and a student. When there is a good fit, this leads to unusually high ratings by that student for the professor, above and beyond what you'd expect given the student's usual rating bias, and given the level of ratings the professor usually attracts.

To zoom in on these relationship effects simply requires factoring out each student's rating bias, and each professor's average rating across students.

The exciting finding is that the researchers were able to use the students' ratings of, and their mood during, the 6-minute trailers to forecast how they later rated the actual lectures, including predicting which professors got the highest average ratings after the lectures, and predicting relationship effects.

This result is important, the researchers explained, because the students' memory for material taught in a given lecture was independently related both to that lecturer's average ratings (some lecturers are better than others), but also to the specific relationship effects (i.e. whether the student in question had given that lecturer unusually high ratings – the sign of a good professor/student fit).

"These findings support the possibility of developing online systems that would provide personalised recommendations that specific students take courses from specific professors," the researchers said.

However, they acknowledged that their results need to be replicated, and they also outlined some limitations of the study. This included the fact they'd carefully compiled the 6-minute trailers to showcase each professor's teaching style (a time-consuming endeavour); that the live evaluations involved just one lecture rather than an entire course; and that the professors' teaching skills were confounded with the topics they taught.

  ResearchBlogging.orgGross, J., Lakey, B., Lucas, J., LaCross, R., R. Plotkowski, A., & Winegard, B. (2015). Forecasting the student-professor matches that result in unusually effective teaching British Journal of Educational Psychology, 85 (1), 19-32 DOI: 10.1111/bjep.12049

--further reading--
Engaging lecturers can breed overconfidence
Is it time to rethink the way university lectures are delivered?

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.