Why moving faces are easier to recognise

Psychologists have previously shown that moving faces are easier to recognise than a static image of a face. Karen Lander and Lewis Chuang at the University of Manchester sought to find out why.

In a first experiment, 48 psychology students viewed degraded facial images of lecturers from their department. The students were split into four groups - one viewed static images only, whereas the other groups saw the faces either moving rigidly (nodding or shaking their head), talking (without sound), or forming a facial expression. Lander and Chuang found that students who observed the faces talking or expressing were better at recognising the faces. Rigid facial movements, by contrast, didn't seem to provide any advantage.

This led them to hypothesise that we may each have a unique way of moving our face - which is revealed when we speak or form an expression. To test this further, they harvested 2.5 second clips of dozens of famous faces from film and TV. Thirty people then rated these clips for how distinctive they thought each face's movement was.

Another 48 students then tried to identify the faces in degraded versions of these clips, as well as trying to identify static images of some of the faces. Lander and Chuang found the students were better able to recognise moving images of the famous faces, compared with static images, but that this advantage was significantly greater when the movement had been deemed distinctive by the earlier raters.

"We speculate that as the face moves in a more 'characteristic' or distinctive manner, so the usefulness of the motion cue is increased", the authors said.
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Lander, K. & Chuang, L. (2005). Why are moving faces easier to recognise? Visual Cognition, 12, 429-442.

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Good news for working mums

Working mums have had their fair share of bad press. Take the 2002 report from the Institute for Social and Economic Research that concluded "There is a negative and significant effect of the mother's full-time employment when the child was aged 0-5, on the child's educational attainment as a young adult". This spawned headlines like "Working mums 'bad for children'" in the Guardian and other papers.

But now there's some good news. An American study involving 1,053 families has found that controlling for a host of other maternal characteristics, a mother's time at work does not have a detrimental effect on her infant's social behaviour or cognitive performance as measured between the ages of 15 to 36 months.

Aletha Huston and Stacey Aronson at the University of Texas twice rang up the mothers in their sample and asked them to recall what they had been doing each hour for the last 24 hours. They also visited the mothers' homes to watch how they interacted with their children and to measure the children's behaviour and cognitive development.

The researchers found that the 580 working mums did spend less time with their children than the non-working mums but the difference was far less than might be expected based on their working hours. That's because working mothers tended to compensate by sacrificing other activities, like housework or socialising, and by spending more time with their children at weekends than non-working mothers. Moreover, the quality of interaction working mothers had with their child tended to be superior - involving more social interaction - playing, talking and holding their infants. Their home environments were also rated as slightly higher quality than non-working mothers'.

"The economic and social benefits of maternal employment outweigh any losses that may result from the time spent away from the child", Huston and Aronson concluded.
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Huston, A.C. & Aronson, S.R. (2005). Mothers' time with infant and time in employment as predictors of mother-child relationships and children's early development. Child Development, 76, 467-482.

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Could high cholesterol be good for your brain?

High cholesterol is bad for your body - it's associated with increased risk of stroke and heart disease - but new research suggests that paradoxically, it could be good for your brain. Cholesterol is a fat-like substance found in the blood and most cells, especially in the brain.

Penelope Elias and colleagues at Boston University analysed data from 789 participants in the Framingham Heart Study. From 1948 to 1974-78, the participants received biennial medical check-ups, some of which included measures of their total serum cholesterol. Then once between 1974 to 1978, the participants completed a comprehensive battery of cognitive tests, including measures of their learning and memory ability, their attention and concentration, executive functioning and abstract reasoning.

Controlling for a plethora of variables, including age, education, occupation, blood pressure, and smoking, the researchers found that lower cholesterol was modestly, but significantly, associated with lower cognitive performance, especially on those subtests related to executive functioning (i.e. the ability to stay focused on the task at hand, or to switch successfully between different types of task).

"These effects have biological plausibility", the authors explained. "Low serum cholesterol and poorer cognitive functioning may be related because neuronal cells require cholesterol for normal metabolic processes".

However, the authors cautioned that cholesterol could simply be a biological marker for some other physiological or psychological factor that affects cognition.

Moreover, this current data was collected before anti-cholesterol drugs had become effective or widespread. "The result of lowering cholesterol with current medications may be very different from naturally low cholesterol", researcher Merrill Elias said. Readers on prescription medication to reduce their cholesterol should note therefore that the benefits to their cardiovascular health will almost certainly outweigh any potential detriment to their cognition.
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Elias, P.K., Elias, M.F., D'Agostino, R.B., Sullivan, L.M. & Wolf, P.A. (2005). Serum cholesterol and cognitive performance in the Framingham Heart Study. Psychosomatic Medicine, 67, 24-30.

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Dangerous liaisons

What makes some women vulnerable to abusive relationships? To find out, April Few and Karen Rosen at the Department of Human Development at Virginia Tech., conducted 120 hours worth of interviews with 28 women (average age 22 years; 21 Caucasians and 7 African-Americans) who had been in an abusive relationship lasting from three months to nine years. According to Few and Rosen, violence occurs within 30 per cent of dating relationships, 50 per cent of which remain intact, thus leading to chronic abuse.

Analysis of the interviews pointed to two dimensions of vulnerability - 'relational vulnerability' and 'situational vulnerability', offset by protective factors like high self-esteem. Relational vulnerability refers to things like whether a woman was exposed to family violence in her childhood, and whether she has developed a 'caretaker identity' that stems from growing up too fast - what the authors call being 'adultified in childhood' - causing her to feel a responsibility to rescue and protect her violent partner. Situational vulnerability refers to a woman's current life circumstances, like being lonely after moving away from family; or feeling the need to be in a serious relationship, or to to lose her virginity after reaching a certain age.

There were also cultural vulnerability factors unique to the African-American participants. They cited the scarcity of eligible Black men, and their concern for protecting the wider perception of Black dating relationships in the community. One woman said "the public often sees Black relationships as dysfunctional; I didn't want to be a statistic".

The study authors said their findings have clinical implications: "...the Vulnerability Conceptual Model may be useful in helping survivors engage in self-reflexive exercises to determine their own relational and situational vulnerabilities". They also recommended "narrative therapy" that "provides options for the telling and retelling of preferred stories of people's lives (their solutions) while deconstructing problems through the techniques of externalisation (separating the person from the problem)".

This research is important, Few and Rosen said, because "Identifying women's vulnerabilities can enlighten those who might want to help women become, as one participant put it, 'abuse proof'".
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Few, A.L. & Rosen, K.H. (2005). Victims of chronic dating violence: how women's vulnerabilities link to their decisions to stay. Family Relations, 54, 265-279.

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Trust in the brain

In one of the first ever studies to simultaneously scan the brains of two people, researchers at the Human Neuroimaging Lab in Texas have furthered our understanding of how the brain represents trust.

Forty-eight pairs of participants took part in an economics game. Groundbreaking 'hyperscanning' software meant that while one person lay in a scanner in Texas, their partner lay in a similar machine hundreds of miles away in California, and yet their brain images could be analysed together.

One partner was given $20 and was the investor. Each round they chose how much money to pass to their partner, the 'trustee'. Both players knew that according to the rules, the money tripled once it was passed to the trustee. The trustee then chose how much of that profit to share back with the investor before the next round began. There were ten rounds.

When an investor raised their next investment despite the trustee having been unfair the previous round, the researchers found that the trustee's brain then reacted in a characteristic way. Their caudate nucleus - a neural area well-connected to the brain's reward pathways - became more active, probably reflecting their increasing 'trust' in the investor's good will. Activity in this region of their brain then also predicted how generously they shared that round's profit.

Moreover, as the game wore on, this differential activity in the caudate began occurring earlier by several seconds, suggesting the trustee was starting to anticipate a generous investment (or not) from their partner as they learned their playing style.

The researchers said: "Taken together, these results suggest that the head of the caudate nucleus receives or computes information about (i) the fairness of a social partner's decision, and (ii) the intention to repay that decision with trust".
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King-Casas, B., Tomlin, D., Anen, C., Camerer, C.F. Quartz, S.R. & Montague, P.R. (2005). Getting to know you: reputation and trust in a two-person economic exchange. Science, 308, 78-83.

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Does "No" to sex mean fewer STDs?

You might think that pledging not to have sex before marriage would reduce a young person's chances of contracting a sexually transmitted disease (STD). Think again.

Hannah Bruckner and Peter Bearman analysed urine samples and questionnaire results provided by 11,471 participants aged 18 to 24 as part of the National Longitudinal Study of Adolescent Health. They found that although the 20 per cent of the sample who had made a virginity pledge were more likely to have sex later and with fewer people, that didn't protect them from STDs - their rates of diseases like Chlamydia, Gonorrhea and Trichomoniasis were no lower than among young people who hadn't made a pledge.

Possible reasons for this include the fact that 61 per cent of the virginity pledgers had had pre-marital sex, despite their promise not to (compared with 91 per cent of non-pledgers), and that many of them engaged in alternative forms of sex as a substitute for intercourse. In fact, virginity pledgers were six times as likely to have had oral sex as non-pledgers. Moreover, abstinence-based sex education often omits advice on using contraception. Consistent with this, virginity pledgers were less likely to report having used a condom the first time they had intercourse.

All this led the authors to conclude: "...a careful evaluation should accompany the generous federal and state funds that abstinence-only programmes have enjoyed". Meanwhile, National Abstinence Clearinghouse President Leslee Unruh described the study as "junk science" and "politically charged".
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Bruckner, H.B. & Bearman, P. (2005). After the promise: the STD consequences of adolescent virginity pledges. Journal of Adolescent Health, 36, 271-278.

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"How sour sweet music is..."

"How sour sweet music is..." Shakespeare wrote in his play Richard II "...when time is broke and no proportion kept!". The musician known to researchers as E.S. can probably sympathise with this quote more than most - she consistently experiences specific tastes, like salt or bitterness, when she hears certain pairs of musical tones. This cross-talk between the senses is called synaesthesia, although it is a rare form. Most synaesthetes experience different colours when they hear sounds or see certain numbers/ words.

Doubters have suggested people with synaesthesia are making it up, or that they have a vivid imagination. But scientists at the University of Zurich tested E.S. on a version of the Stroop task and found evidence that what E.S reports is real. E.S. was able to identify musical tone-intervals faster than five control musicians when researchers applied to her tongue the taste that she normally experiences with a given tone-interval. Yet she was slower than controls with incongruent tastes applied to her tongue. In contrast, the different tastes didn't affect the control musicians' performance.

"This demonstrates that synaesthesias may be used to solve cognitive problems", Gian Beeli and his colleagues said.

Moreover, when the researchers presented E.S. with single taste-related words (rather than applying actual tastes to her tongue), they had no effect on her tone-interval Stroop task performance - thus suggesting strongly that the synaesthesic effect was sensory, not conceptual, and occurred via cross-talk between her auditory and gustatory senses.

There is a downside for E.S. though. According to New Scientist magazine, her synaesthesia affects her musical choice - for example, Bach's music is a favourite because it's particularly creamy.
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Beeli, G., Esslen, M. & Jancke, L. (2005). When coloured sounds taste sweet. Nature, 434, 38.

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Seeing what things are

As soon as we know something is there, we already know what category of thing it is. That's according to Kalanit Grill-Spector and Nancy Kanwisher at Stanford University and MIT.

They showed people images for between 17 to 167ms, some of which contained an object - a jeep or a German shepherd dog, for example - some of which just showed an incoherent scramble of images. Sometimes participants had to say as fast as they could whether an object was present or not ('detection'), other times they had to indicate what category the object belonged to (e.g. a car or a dog), other times they had to identify the object specifically (e.g. to indicate as fast as possible whether or not the object was a German shepherd dog, for example).

People took no longer to categorise an object than they took to detect whether an object was present or not. Moreover, on trials when categorisation performance failed, detection performance was no better than chance, and vice versa, thus suggesting the processes were mutually dependent on each other. This has important implications for theories of visual object recognition. It suggests that segmentation of a visual scene into background and foreground, needed to detect objects, occurs at the same time as object categorisation. Either that, or conscious awareness only kicks in after the categorisation stage.

However, identifying an object took longer by about 65ms, suggesting object identification occurs only after its category has been determined.
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Grill-Spector, K. & Kanwisher, N. (2005). Visual recognition. As soon as you know it is there, you know what it is. Psychological Science, 16, 152-159.

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Do mums know about child development?

An American study has tested how much mothers know about child development, safety issues in raising children, infant sleeping habits and nutrition.

Two hundred and three women at a paediatric clinic and an obstetric clinic in a southern state in America were approached by a researcher. The women were mothers or mothers-to-be aged from 18 to 52 years, and were predominantly Caucasian (52 per cent) or African American (39 per cent).

Overall, the mothers answered 65 per cent of questions correctly, being most aware of the importance of establishing eating and sleeping routines (82 per cent correct) but least aware of how much sleep infants need (26 per cent correct) or what 6-month-olds are capable of doing (53 per cent correct).

"On average, women overestimated development by three months or more" Stephanie Reich of Vanderbilt University said. "This is a disturbing finding, as research in child maltreatment suggest abusive parents tend to overestimate their child's abilities".

Mothers who'd had more education tended to answer more questions correctly. Non-White mothers tended to score less well - "this may be because non-White families tend to have less continuous care and report having a less participatory relationship with their paediatrician", Reich said "therefore leading to less provision of anticipatory guidance".

"What is needed now are ways to educate mothers about typical child development" Reich said. "Preliminary research has shown parenting classes are effective in teaching parents about typical child development".

"Since maternal knowledge affects how mothers raise their children, increasing knowledge about typical child development would be beneficial" Reich concluded.
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Reich, S. (2005). What do mothers know? Maternal knowledge of child development. Infant Mental Health Journal, 26, 143-156.

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Walking away from dementia

By Natalie Taplin at Totton College

Elderly people who are more physically active are protected from cognitive decline. That's the message from an American study led by Jennifer Weuve at the Harvard School of Public Health.

In 1986, part of the Nurses Health Study began tracking physical activity in more than 18,766 women aged 70-81, all of them former nurses. The women completed a baseline cognitive test over the telephone in 1995 and then again every two years until 2001.

Women who engaged in more leisure activity showed less cognitive decline and higher levels of cognitive function. Even those women who only walked a leisurely 90 minutes a week had better cognitive scores than those who walked less than 40 minutes a week.

It would appear that the differences in cognitive ability in women with higher vs. lower levels of activity, were similar to the differences in cognitive ability among women two to three years apart in age. So, on average, women who were 80 and highly active, had minds that functioned as if they were 77!

Overall, elderly women in the most active set had a 20% lower risk of cognitive impairment than those who were least active. "Physical activity may directly affect the brain", the authors explained "potentially preserving neuronal structure and promoting the expansion of neural fibres, synapses and capillaries".
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Weuve, J., Kang, J.H., Manson, J.E., Breteler, M.M.B., Ware, J.H. & Grodstein, F. (2004). Physical Activity, Including Walking, and Cognitive Function in Older Women. Journal of the American Medical Association, 292, 1454-1460.

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Words can't explain maths

Psychologists have argued that mathematical ability depends on the same cognitive skills and processes that underlie language. But now a study by psychologists at the University of Sheffield shows you don't need language to do maths. They tested three men, all of whom had damage to the left perisylvian region of their brain, known to subserve language ability.

The men were unable to distinguish between sentences like 'The man killed the lion' and 'The lion killed the man', yet they were able to perform comparable maths tasks that depend on analogous syntactic rules, like distinguishing between '59 minus 13' and '13 minus 59'.

Similarly, the men - referred to in the research report as S.A., S.O. and P.R. - were able to use a pencil and paper to solve simple mathematical expressions like '36 divided by (3 x 2)' that depend on understanding embedded clauses, yet they couldn't understand the verbal equivalent - sentences like 'This is the dog that worried the cat that ate the rat that ate the malt that lay in the house that Jack built'.

Rosemary Varley and her collaborators argue this shows the functional and neuroanatomical independence of maths and language: "...mathematics can be sustained without the grammatical and lexical resources of the language faculty", they said. Their findings also undermine the argument that complex thought cannot occur without language.

However, because the participants in this study were not brain damaged from birth, this research does not rule out the possibility that the acquisition of mathematical ability might depend on language, either in an individual's development, or evolutionarily.
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Varley, R.A., Klessinger, N.J.C., Romanowski, C.A.J. & Siegal, M. (2005). Agrammatic but numerate. Proceedings of the National Academy of Sciences, 102, 3519-3524.

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A secret investigation

Secrets range from the trivial - not telling a friend you borrowed their shoes - to the serious - not telling your partner that you're HIV positive, for example. John Caughlin at the University of Illinois and his colleagues investigated whether people's reasons for withholding a secret predict how long the secret will last, and how good people are at predicting the consequences of revealing their secret.

Two hundred and eighteen students with a secret were recruited. They stated what their secret was, who they were keeping it from (most cited a friend or romantic partner), why they were keeping it secret, and what they thought would happen if they gave the secret away. Two months later they stated whether they'd revealed their secret (63 had) and what the consequences were. Secrets ranged from things like "When I was a child I was molested by a family member" to "I still have feelings for my first love".

To some extent it was possible to predict which secrets would be revealed. Students who at the outset were less concerned about being negatively evaluated after revealing their secret, or who were less worried about the impact the revealed secret might have on their relationship (with their confidant), were more likely to have revealed the secret two months later.

The students also showed a modest ability to accurately predict the consequences of revealing their secret. In fact, how they said their friend/partner/relative reacted, tended to be more positive than they had predicted that person's reaction would be two months earlier. So go on, sharing that secret might not be as awkward as you think...
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Caughlin, J.P., Afifi, W.A., Carpenter-theune, K.E. & Miller, L.E. (2005). Reasons for, and consequences of, revealing personal secrets in close relationships: a longitudinal study. Personal relationships, 12, 43-59.

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