Emotion research gets real - Was this person just told a joke or told they have great hair?

How accurately could you tell from a person's display of behaviour and emotions what just happened to them?  Dhanya Pillai and her colleagues call this "retrodictive mindreading" and they say it's a more realistic example of how we perceive emotions in everyday life, as compared with the approach taken by traditional psychological research, in which volunteers name the emotions displayed in static photos of people's faces.

In Pillai's study, the task of a group of 35 male and female participants wasn't to look at pictures and name the facial expression. Instead, the participants watched clips of people reacting to a real-life social scenario and they had to deduce what scenario had led to that emotional display.

Half the challenge Pillai and her colleagues faced was to create the stimuli for this research. They recruited 40 men and women who thought they were going to be doing the usual thing and categorising emotional facial expressions. In fact, it was their own responses that were to become the stimuli for the study proper.

While these volunteers were sitting down ready for the "study" to start, one of four scenarios unfolded. The female researcher either told them a joke ("why did the woman wear a helmet at the dinner table? She was on a crash diet"); told them a story about a series of misfortunes she'd encountered on the way to work; paid them a compliment (e.g. "you've got really great hair, what shampoo do you use?"); or made them wait 5 minutes while she had a drink and did some texting. In each case the volunteers' emotional responses were recorded on film and formed the stimuli for the real experiment.

The researchers ended up with 40 silent clips, lasting 3 to 9 seconds each, comprising ten clips for each of the four scenarios. The real participants for the study proper were first shown footage of the researcher in the four scenarios and how these were categorised as joke, story, compliment or waiting. Then these observer participants watched the 40 clips of the earlier volunteers, and their task in each case was to say which scenario the person in the video was responding to.

The observing participants' performance was far from perfect - they averaged 60 per cent accuracy - but it was far better than the 25 per cent level you'd expect if they were merely guessing. By far, they were most skilled at recognising when a person was responding to the waiting scenario (90 per cent accuracy). Their accuracy was even for the other scenarios at around 50 per cent. They achieved this success level despite the huge amount of variety in the way the different volunteers responded to the different scenarios. "From observing just a few seconds of a person's reaction, it appears we can gauge what kind of event might have happened to that individual with considerable success," the researchers said.

A surprise detail came from the recordings of the observing participants' eye movements. They focused more on the mouth region rather than the eyes. Based on past research (much of it using static facial displays), Pillai and her colleagues thought that better accuracy would go hand-in-hand with more attention paid to the eye region of the targets' faces. In fact, for three of the scenarios (all except the joke), the opposite was true. This may be because focusing on the eye region is more beneficial when naming specific mental states, as opposed to the "retrodictive mindreading"challenge involved in the current study.

In contrast to much of the existing psychology literature, Pillia and her team concluded that theirs was an important step towards devising tasks "that closely approximate how we understand other people's behaviour in real life situations."

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Pillai, D., Sheppard, E., and Mitchell, P. (2012). Can People Guess What Happened to Others from Their Reactions? PLoS ONE, 7 (11) DOI: 10.1371/journal.pone.0049859

Note: the picture above is for illustrative purposes only and was not used in the study.

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

Disgusted people have enhanced ability to spot dirt

The cool, calm extravert - that's the emotional profile that our culture puts on a pedestal. Prudes, introverts and scaredy-cats just aren't fashionable.

Yet there's mounting psychological research showing that unpopular emotional traits often come with advantages. The anxiously attached are quicker to detect danger, such as smoke in a room; those with trait anxiety have fewer accidents; introverts speak in a way that's perceived as more trustworthy. Now Gary Sherman and his colleagues have published research showing how prudish disgust-sensitivity is associated with a superior ability to detect impurities.

Over one hundred students had to judge repeatedly which of four squares on a computer screen was the odd-one-out in terms of its shading. The squares were either light grey against a white background, with one slightly darker or lighter than the others (akin to spotting dirt against a white background); or they were dark grey against a black background, with one slightly darker or lighter than the others.

Students more prone to disgust (they agreed with statements like "it would bother me to see a rat run across my path") tended to have heightened sensitivity for spotting grey shades against a white background, similar to spotting dirt on a clean surface. They displayed no such heightened sensitivity at the other end of light spectrum - grey on black.

A second study was similar, but this time students more prone to disgust had heightened sensitivity when identifying digits written in light grey against a white background (yet they were no better at spotting grey digits against a mid-grey background).

In a final study, looking at disgusting pictures (e.g. maggots on meat) boosted the ability of disgust-sensitive participants to spot grey digits against a white background. Participants low in disgust sensitivity didn't show this response to the pictures, perhaps because they were unmoved by them.

The effect documented here is a form of perceptual tuning, like the way in infancy we gradually lose our ability to hear sounds that feature in foreign languages. It's not clear if being disgust prone leads to more exposure to clean white surfaces, and so more practice and superior ability at seeing darker shades against a light background. Or if instead, some people have heightened sensitivity at this end of the colour spectrum, which has the effect of making them more prone to disgust. Or both, in a self-perpetuating cycle.

"Disgust not only makes people want to avoid impurities," the researchers said, "but also makes people better able to see them."

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Sherman, G., Haidt, J., and Clore, G. (2012). The Faintest Speck of Dirt: Disgust Enhances the Detection of Impurity. Psychological Science, 23 (12), 1506-1514 DOI: 10.1177/0956797612445318

--Further reading--
More research items on disgust.

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

How to kill an earworm

If earworms - songs that play in your head - drive you crazy, you'll welcome clues for how to eradicate them that come from a new study by psychologists at Western Washington University, USA.

First - and I realise this doesn't sound appealing - try to avoid songs that you like. The new research suggests they are most likely to become lodged in your head (contrary to the myth that it's obnoxious songs with most earworm potential). If you must listen to a favoured song, check to see if it starts playing in your head right afterwards. If it does, then it's well on its way to becoming an earworm. This is a particular risk is you find that only a part of the song plays in your head.

Ira Hyman Jr. and his colleagues believe this last detail may be a manifestation of the classic Zeigarnik Effect, whereby incomplete tasks remain in memory but evaporate once completed. In the case of earworms, the researchers propose that the playing of only a part of a song in your head leaves it incomplete and thereby increases the likelihood that it will return against your will as an earworm. This insight suggests that one way to squash a developing earworm is to make sure, once a song starts playing in your head, that you see it all the way through (perhaps you will need to listen to the track again to ensure this is possible).

Finally, after listening to music, try to avoid mental tasks that are either too easy or too difficult. Any kind of activity that increases your mind-wandering will also provide fertile ground for an earworm to develop. In the same vein, engaging in an absorbing task will tie up your mental resources and deny the earworm the chance to grow.

These insights are based on a survey and several lab experiments conducted by Hyman Jr. and his team. The survey of 299 students revealed that enjoyable, recently heard songs were more likely to become earworms; that a huge variety of songs become earworms; that musicians experience them more often and re-experience more aspects of songs.

In the experiments, dozens of students listened to and rated three songs by the Beatles and by more contemporary acts like Gaga (ostensibly as part of a completely different research study), then they completed a puzzle task. Afterwards they revealed whether any of the songs had started playing in their heads, and 24 hours later they reported whether the songs had returned as earworms.

Overly challenging sudoku or anagram tasks helped breed more earworms (the former more so than the latter). Beatles songs were just as likely to become earworms as modern hits. Songs played later in the experimental session (therefore more recently heard) were more likely to become earworms; and a song that started playing in the head soon after listening was more likely to become an earworm over the next 24 hours. Only playing part of songs to students, as opposed to the whole track, did not increase the risk of earworms.

"Songs frequently come to mind as intrusive thoughts, and intrusive song cycles are easy to start in both naturalistic and laboratory situations," the researchers said. "In our experimental studies, we have documented that intrusive song cycles are easy to start and manipulate. Therefore, songs may provide a valuable tool for examining why intrusive thoughts occur and how to control intrusive thought cycles."

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Hyman, I., Burland, N., Duskin, H., Cook, M., Roy, C., McGrath, J., and Roundhill, R. (2012). Going Gaga: Investigating, Creating, and Manipulating the Song Stuck in My Head. Applied Cognitive Psychology DOI: 10.1002/acp.2897

--Further reading--
Hearing music that isn't there
A natural history of the Earworm - the song that won't get out of your head
What triggers an Earworm - the song that's stuck in your head?


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

Paranormal believers and religious people are more prone to seeing faces that aren't really there

Our brains are so adept at detecting faces that we often see them in random patterns, such as clouds or the gnarled bark of a tree. Occasionally one of these illusory faces comes along that resembles a celebrity and the story ends up in the news - like when Michael Jackson's face appeared on the surface of a piece of toast. A new study asks whether some people are more prone than others to perceiving these illusory faces.

Tapani Riekki and his team collected dozens of photos that judges in pilot work agreed did or did not have the appearance of faces in them (this included pictures of furniture, places, and natural scenes, such as a rock-face). The researchers then used two adverts to recruit their participants - they were identical except that one requested people who "view the paranormal positively or believe that there is an invisible spiritual world," while the other requested people who are "sceptical about paranormal phenomena".

Forty-seven people were eventually selected to take part, based on their being particularly paranormal-believing, religious, sceptical or atheist (there was a lot of overlap in membership between the first two and final two categories). The participants were shown the photos and had to indicate whether a "face-like area" was present, where it was in the image, and they had to say how face-like the image was, and how emotional.

The key finding is that people who scored high in paranormal belief or religiosity were more likely to see face-like areas in the pictures compared with the sceptics and atheists. They weren't more sensitive to the illusory faces as such, because they also scored a lot of false alarms - saying there was a face when there wasn't. However, when they spotted a face-like pattern correctly, they were more accurate than sceptics and atheists at saying where exactly in the pictures the illusory faces were located. Finally, the paranormal believers rated the illusory faces as more face-like and emotional than the sceptics.

The researchers said their findings are consistent with past research showing that belief in the paranormal tends to go hand-in-hand with a tendency to jump to conclusions based on inadequate evidence. They added that the results support the idea that religious people and paranormal believers have the habit of seeing human-like attributes, including mental states, in "inappropriate realms."

"We may all be biased to perceive human characteristics where none exist," Riekki and his team concluded, "but religious and paranormal believers perceive them even more than do others."

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Riekki, T., Lindeman, M., Aleneff, M., Halme, A., and Nuortimo, A. (2012). Paranormal and Religious Believers Are More Prone to Illusory Face Perception than Skeptics and Non-believers. Applied Cognitive Psychology DOI: 10.1002/acp.2874

Post written by Christian Jarrett for the BPS Research Digest.

When not to pat someone on the shoulder

Physical touch can be surprisingly persuasive. From diners giving larger tips to waiters who touch them, to people being more helpful to strangers who pat them lightly on the arm, the literature has tended to paint a positive picture of the emotional influence of social touch. But now a study out of Belgium has documented what you might call the dark side of social touching. This isn't about unwanted groping, which is always inappropriate. It's about the fact that context is everything for light social touches, with the new research showing that even a friendly pat on the shoulder can have an adverse effect if it's performed in the wrong situation.

Jeroen Camps and his colleagues had 74 student participants perform a maze challenge in a race against a partner. The outcome was fixed so the participant won by a tiny margin, and then, as the pair left the room, the partner (actually a male or female stooge planted by the researchers) patted the participant on the shoulder lightly three times, smiled gently and wished them good luck for the next task. For participants in the control condition, all this was the same but without the shoulder patting. Next, the participants and their partner went to another room and completed "the dictator game", a simple economic game that involved the participant choosing how many movie-prize credits to share with their partner.

The revealing finding was that participants who'd been patted on the shoulder shared fewer credits with their partner, suggesting that touch can backfire when it's performed in a competitive context, perhaps because it's interpreted as a gesture of dominance. Interestingly, there was no link between participants' awareness of whether they'd been touched and their sharing behaviour; participants who remembered the touch rated it as neutral; and the partner wasn't rated as more unpleasant in the touch condition. All of which suggests the adverse effect of touch on later cooperation was probably non-conscious.

A second study was similar but this time participants and their partner (another stooge, always female) either competed against each other on a puzzle or they cooperated. Again, afterwards, the partner wished them luck, smiled, and either did or didn't pat them on the shoulder at the end, before they both moved to another room to play the dictator game. The results were clear - in a competitive context, touched participants subsequently shared fewer movie-prize credits with their partner, compared with those participants who weren't touched. By contrast, in the cooperative context, touched participants went on to be more generous with their partner, as compared with participants who weren't touched.

"Despite what some people might think, touching someone else may thus not always have desirable social consequences," the researchers said. "A simple tap on the shoulder, even with the best intent, will do nothing but harm when used in the wrong place at the wrong time."

A limitation of the research is the use of a shoulder pat. It could be argued that this is a form of touch with specific connotations, depending on the context. For instance, maybe it is construed as condescending in a competitive situation. By contrast, a lot of the earlier research on the benefits of touch have tended to use a simple, light touch on the arm, which is perhaps a more neutral gesture.

What do you think? Are there any instances when you've been touched lightly (in a non-sexual way) and it's irritated you? Or times that it's endeared you to the toucher? Was it the context that made the difference?

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Camps, J., Tuteleers, C., Stouten, J., and Nelissen, J. (2012). A situational touch: How touch affects people's decision behaviour. Social Influence, 1-14 DOI: 10.1080/15534510.2012.719479

--Further reading--
The power of a light touch on the arm
Why is a touch on the arm so persuasive?

Post written by Christian Jarrett for the BPS Research Digest.

Why do humans walk in circles?

It's a trusted plot device of many a thriller. The lost protagonists stagger for hours through creepy forest only to end up back where they started. In fact the idea that humans walk in circles is no urban myth. This was confirmed by Jan Souman and colleagues in a 2009 study, in which participants walked for hours at night in a German forest and the Tunisian Sahara. But the question remains - why?

Souman's team rejected past theories, including the idea that people have one leg that's stronger or longer than the other. If that were true you'd expect people to systematically veer off in the same direction, but their participants varied in their circling direction.

Now a team in France has made a bold attempt to get to the bottom of the mystery. Emma Bestaven and her colleagues hired out a huge indoor exhibition space in Bordeaux (90m x 150m) and blindfolded their participants, thus ensuring that there was no way any environmental sounds or bumps on the ground could interfere with the results.

Another innovation was that the researchers used EMG to monitor the participants' muscle activity in their legs whilst they walked; they had them stand on a force plate to check how their balance was distributed; and they assessed their subjective sense of the vertical, via their placement of a vertical bar.

Given six attempts to walk in a straight line, the fifteen blindfolded participants (7 women) in fact frequently veered off in one direction or the other, just as expected based on past research. Half the time they deviated off to the left, 39 per cent of the time to the right, and the remainder of the walks they managed to go straight. Six of the participants always veered in the same direction, the others mixed it up. There was no evidence of participants getting straighter with each attempt, but a faster walking speed was associated with a straighter trajectory.

Many past theories for why humans walk in circles were ruled out - walking deviation was unrelated to hand, eye or leg dominance. The recordings of muscle activity drew a blank. But there was one clue. The participants' "centre of pressure" score obtained when they stood on the force plate, which reflects their postural balance, was correlated with how much they deviated from a straight line when they walked. In turn, this "centre of pressure" score was correlated with participants' subjective sense of a straight vertical line.

Taken together, Bestaven's team said this suggests that our propensity to walk in circles is related in some way to slight irregularities in the vestibular system. Located in inner ear, the vestibular system guides our balance and minor disturbances here could skew our sense of the direction of "straight ahead" just enough to make us go around in circles.

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Emma Bestaven, Etienne Guillaud, and Jean-René Cazalets (2012). Is “Circling” Behavior in Humans Related to Postural Asymmetry? PLoS ONE DOI: 10.1371/journal.pone.0043861

Post written by Christian Jarrett for the BPS Research Digest.

Targets look bigger after a shot that felt good

Bigger targets are easier to hit, obviously. But did you know this relationship works backwards? That is, targets that we consider hittable look bigger as a result. The finding is consistent with James Gibson's Theory of Affordances, whereby the ways we can use our bodies to interact with the environment affects our perception of that environment.

Yang Lee at Gyeongsang National University in South Korea, and his colleagues, began their study by asking nine experienced archers to fire at targets of five different sizes located 50 meters away. After they released each arrow, the participants were instructed to turn their heads so that they couldn't see the path of their shot. Upon each arrow hitting home, a screen was also pulled across to prevent the archers from seeing how successful they'd been.

After each shot, the archers chose which of 18 miniature targets on a card most closely matched the size of the target they'd just fired at. The size of the miniatures went from 10mm diameter to 27mm, designed to represent the apparent size of the real target, as seen from a 50m distance.

Although they couldn't see the success of the shots they'd fired, the archers' judgements of the size of the targets was related to the accuracy of their shots. In fact, their size judgments were more strongly related to their accuracy than they were to the actual size of the targets. Specifically, targets were perceived as bigger after a more accurate shot, even though the archers had no access to objective feedback about their performance.

Lee and his colleagues think that archers are able to tell how hittable a shot is based on bodily feedback about their form and chances of success. If a target is hittable then it is adaptive (i.e. useful in an evolutionary sense) that it should be perceived as larger. To test this idea, a second study involved 20 novices preparing to shoot arrows at targets located 50m away. In this study, the participants didn't actually fire the arrows. After each drawing of an arrow, they stopped and estimated the size of the distant target. The crucial twist was that some arrows were drawn back with the aid of a stabilising tripod and some weren't. The aim of the stabiliser was to provoke the sense in the archers, based on bodily feedback, that they had a better chance of hitting the target. In turn this was expected to affect their perception of the targets. That's exactly what was found - targets were perceived to be larger after they'd been viewed in the context of a stabilised draw back.

These intriguing new findings add to a growing literature linking performance with size estimations - for example, it's also been shown that golf putters perceive holes as bigger after a successful putt.

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Lee Y, Lee S, Carello C, & Turvey MT (2012). An Archer's Perceived Form Scales the "Hitableness" of Archery Targets. Journal of experimental psychology. Human perception and performance PMID: 22731994

Post written by Christian Jarrett for the BPS Research Digest.

Music we like can be more distracting than music we don't

Music by Infernal: enjoyable but distracting 

Many of us like to listen to music while we work. It's become a ritual, alongside the coffee in our favourite mug. Previous research suggests this is probably no bad thing. In lab studies, people who listen to music they like, generally perform better at mental tasks afterwards, an effect that's been attributed to boosts in mood and arousal.

But what about the effect of background music that plays on during a task - more akin what we do in real life? This is actually less studied. The traditional mood-arousal literature would predict it to be beneficial too, especially if the music is to the listener's taste.

However, there's another line of research, known as the "Irrelevant Sound Effect", that's all about the way background sounds can interfere with our short-term memory for ordered lists, which would be a bad thing for many work-related tasks. These studies show that the distraction is greater when the sound is more acoustically varied - just like your typical pop song. Based on this, Nick Perham and Martinne Sykora made a counter-intuitive prediction - background music that you like will be more detrimental to working memory than unappealing music, so long as the liked music has more acoustical variation than the disliked music.

Twenty-five undergrads completed several serial recall tasks. They were presented with strings of eight consonants and had to repeat them back from memory in the correct order. Performance was best in the quiet condition, but the key finding was that particiants' performance was worse when they completed the memory task with a song they liked playing over headphones (Infernal's "From Paris to Berlin"), compared with a song they disliked (songs such as "Acid Bath" from the grind core metal band Repulsion). In case you're wondering, participants who liked Repulsion were excluded from the study.

The fast-tempo "extreme guitar-based" music of Repulsion, the researchers explained, is like "a cacophony of sound, in which the segmentation of each individual sound from the next is difficult to identify". This means it has less acoustic variation from one moment to the next, which helps explain why, even though disliked, it had a less detrimental effect on serial recall than Infernal's pop song.

Perham and Sykora said their findings were "seemingly incompatible with the mood and arousal literature, but are consistent with the changing-state explanation of the Irrelevant Sound Effect."

A further intriguing detail from the study is the participants' lack of insight into the degree of distraction associated with each type of music. Asked to judge their own performance, they determined correctly that their memory was more accurate in the quiet condition, but they didn't realise that their performance was poorest whilst listening to the music they liked.

So, the next time you're bothered by someone else's bad music, console yourself that the noise could be less harmful to your work performance than your own choice would be!

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Nick Perham and Martinne Sykora (2012). Disliked Music can be Better for Performance than Liked Music. Applied Cognitive Psychology DOI: 10.1002/acp.2826

Post written by Christian Jarrett for the BPS Research Digest.

Introducing "inattentional deafness" - the noisy gorilla that's missed

One of the most famous experiments in cognitive psychology (pdf) involved a person in a gorilla suit walking through a basketball game between two teams of players, one dressed in white, the other in black. Told to count passes between the players in white, most people who watched a video of this scene completely failed to notice the gorilla. The experiment provided a dramatic demonstration of what's known as inattentional blindness - our failure to process unexpected visual stimuli that we aren't paying attention to. Now a pair of researchers at Royal Holloway, University of London have provided the first demonstration of prolonged inattentional deafness. Their participants failed to hear a man walk through an auditory scene for nineteen seconds saying repeatedly "I am a gorilla".

Polly Dalton and Nick Fraenkel first created a real auditory scene lasting 69 seconds, in which two conversations about a party took place: one between a pair of women located on one side of the room, the other between a pair of men located on the other. The sounds were recorded via a dummy's head with microphones implanted in its "ears", thus simulating as closely as possible what it would be like for a person to actually hear the scene unfold in real life. Thirty-three seconds into the scene, a man entered from the back of the room and for 19 seconds walked through the scene uttering "I am a gorilla" (listen to the recording).

In an initial study, 40 participants listened to the scene and they were told to pay attention either to the men's conversation or the women's. Afterwards they were asked if they'd heard anything odd. Of the participants who were focused on the men's conversation, 90 per cent noticed the gorilla. In stark contrast, just 30 per cent of participants who were focused on the women's conversation noticed the gorilla.

So, in the same way that tuning out the sight of the basketball players in black led most participants (in the classic research) to miss the sight of an unexpected black gorilla, tuning out the sound of the men's conversation led most participants in this study to completely miss the sound of a male-voiced gorilla.

A potential confound in this new study is that as the auditory gorilla passed through the room, he walked behind the location where the two men were talking. This means that participants focused on the women could have been ignoring male voices and/or one particular side of space. In a second study, the location of the auditory gorilla was reversed so that he passed behind the women. This time 55 per cent of participants focused on the women's conversation still failed to notice the gorilla even though he actually passed on the same side of space that they were focused on.

"The present experiments show that the absence of attention can leave people 'deaf' to a sustained and dynamic auditory stimulus that is clearly noticeable under normal listening conditions," the researchers said, "providing the first ever demonstration of sustained inattentional deafness."
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Dalton P, & Fraenkel N (2012). Gorillas we have missed: Sustained inattentional deafness for dynamic events. Cognition PMID: 22726569

Previously on the Digest blog "Change deafness" - the scant attention we pay to the voice on the end of the phone".

Post written by Christian Jarrett for the BPS Research Digest.

The new psychology of everyday playing cards

Aces are easier to see and remember than other cards

Playing cards, used for games and magic, are so familiar, yet we know remarkably little about the way we perceive and think about them. Are some cards more memorable than others? Are some easier to identify? With so much at stake in games like poker, and card magic a staple of family entertainment, it's surprising that no-one has thought to study this before.

Jay Olson, Alym Amlani and Ronald Rensink first tested if some Western playing cards are easier to spot than others. Ninety-six students were shown visual streams of 26 playing cards on a computer, each displayed for a tenth of a second, and they had to say if a certain target card was present in the stream or not. The students were pretty good, achieving an accuracy rate of 80 per cent, but they performed better for some cards than others. For example, they detected the Ace of Spades more easily than any other card, and they detected Aces in general more easily than other cards - probably because of their simple, distinct pattern. Surprisingly, face cards (e.g. Jack, Queen etc) were no easier to spot than number cards, despite being more distinctive. Another curious finding was the students' particular tendency to say the two red sixes (Six of Hearts and Six of Diamonds) were present when they weren't. It's not clear why.

To test the memorability of cards, Olson's team employed a similar methodology. The students saw a stream of seven cards, each displayed for a quarter of a second, and then they were asked to say whether a particular card had been in the stream or not. Again, the Ace of Spades especially, and all Aces to a lesser extent, were more memorable than other cards.

What about likeability? Students were shown pairs of cards and in each case had to say which they preferred. Regards numerical value, the participants liked the highest (10) and lowest (2) cards the most. And they had a tendency to prefer Spades and Hearts over Clubs and Diamonds - maybe because of their rank in games, or their curved shape. Two cards were especially popular - the Ace of Hearts and the King of Hearts. There was also a gender difference in taste. Men tended to prefer higher value cards and women to prefer lower value.

Finally, the researchers looked at the verbal and visual accessibility of cards. To do this they asked a new batch of hundreds of students (some of them online and some in the lab) to "Name a playing card" or to "Visualise a playing card" and then say which it was. Simply asked to name a card, there was a strong bias for choosing the Ace of Spades, followed by the Queen of Hearts and then other high-ranking cards. When participants chose a number card, there was a bias for naming 3s and 7s the most and 6s the least (a phenomenon well known by magicians). Overall, cards from the Spades and Hearts were chosen more than the other two suits. There was a gender difference again: men tended to name the Queen of Hearts more than women, and women more often named the King of Hearts than men. These same results were pretty much repeated when participants were asked to visualise a card before naming it.

The different card features investigated here tended to interact in ways you might expect. For example, the same cards that participants tended to say mistakenly were in a visual stream, also tended to be the most accessible verbally and visually. More accessible cards were also liked more.

Olson's team acknowledged that their study was limited by the fact that they only studied a sample of Canadian students. But still, they said their work could "serve as a foundation for more rigorous studies of card magic", and more generally could "provide new perspectives on how people perceive and evaluate everyday objects."

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Jay Alson and Alym Amlani (2012). Perceptual and cognitive characteristics of common playing cards. Perception DOI: 10.1068/p7175

Read more Digest posts on the psychology of magic.

Post written by Christian Jarrett for the BPS Research Digest.

You can't resist the pull of another person's gaze

At just the moment the magician swaps the position of two cards in her left hand, she looks across deliberately and misleadingly to her right hand and your attention follows. You can't help it. You see where she's looking and your attention is sent automatically in the same direction. Magicians have known this power for centuries and now psychologists are confirming and measuring the effect under tightly controlled laboratory conditions. More surprising, perhaps, is their finding that the directing effect of arrows is also impossible to resist.

Giovanni Galfano and his colleagues in Italy instructed dozens of participants to look out for a small target that would appear on-screen, each trial, either on the left-hand side or the right-hand side. When it appeared, the participants' task was to press the space-bar key on a keyboard as quickly as possible.

To make things even easier, a word,"left" or "right" (in Italian), appeared in the middle of the screen giving the participants advance warning, with 100 per cent accuracy, as to which side the target would appear. In another run of trials, there was no need for advance warning from a directional word because the target always appeared on the same side.

The only complicating factor in this arrangement - but it's a crucial one - is that after the directional word had gone (on those trials where there was one), and before the target had appeared, a cartoon face popped up in the middle of the screen, looking either in the direction of where the target would appear, or the opposite direction. In other versions of the experiment, rather than a face, an arrow appeared, pointing either towards the side where the target would appear, or towards the opposite side.

The participants were told explicitly to ignore these faces and arrows. But they couldn't. When the cartoon face was looking in the opposite direction to the side the target appeared on, participants were significantly slower to spot the target and press the space key. And it was the same with arrows that pointed in the wrong direction. It's as if the faces and arrows had irresistibly grabbed the participants' attention and sent it momentarily in the wrong direction.

The slowing effect of the gaze and arrows was only a few milliseconds, but it was statistically significant. "The finding that the information conveyed by distractors interfered with the task indicates that orienting of attention mediated by both gaze and arrows resists suppression and can be defined as strongly automatic," the researchers said.

Galfano's team added that the processes underlying the pulling power of gaze and arrows are not necessarily the same. The pull of another's gaze is apparent in the looking behaviour of new-born babies aged just two days, suggestive of an innate mechanism. The power of arrows, by contrast, is obviously based on learned symbolism.

The researchers conceded that different results may have emerged in a more complicated environment more akin to the real world, something they plan to investigate in the future. Related to this, it's been shown that the social identity of a gazer influences the attention-grabbing power of their gaze. A study published last year found that right-wing participants were more affected by the gaze direction of Silvio Berlusconi than were left-wing participants.

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Galfano, G., Dalmaso, M., Marzoli, D., Pavan, G., Coricelli, C., and Castelli, L. (2012). Eye gaze cannot be ignored (but neither can arrows). The Quarterly Journal of Experimental Psychology, 1-16 DOI: 10.1080/17470218.2012.663765

Post written by Christian Jarrett for the BPS Research Digest.

The particular pleasure of scratching an itch on the ankle

It's only in recent times that scientists have discovered there are dedicated nerve pathways for communicating the sensation of itch. This troublesome skin signal provides us with a mixed experience. The prickly discomfort of an itch can be agonising. Yet to scratch an itch is one of life's great pleasures. In fact, it often seems that the more intense the itch, the more unreachable its source, then the greater the ultimate pleasure that's derived from finally reaching and clawing at it.

Now the aptly named Gil Yosipovitch and his colleagues have performed one of the first comparisons to see if itches are itchier on some body parts than others. They also investigated whether scratching itches in some places brings more satisfaction than others.

The researchers used cowhage spicules to induce itchiness on either the forearm, ankle or the back of 18 healthy volunteers (10 women; mean age 34). After the spicules were applied, each volunteer indicated from one to ten the intensity of the itch every 30 seconds for five minutes. The itch was then scratched by an experimenter using a cytology brush (a brush with stiff bristles and an elongated handle). The participants again indicated every 30 seconds the intensity of the itch and the pleasure derived from the scratching.

The main findings were that itches were perceived as more intense on the ankle and back, as compared with the forearm. Similarly, scratching was more pleasurable on the ankle and the back than on the forearm. The greater the itch intensity on the forearm and ankle, the more pleasure came from the scratching. Meanwhile, for the back and forearm, as the itch subsided, the pleasure from scratching faded. By contrast, scratching an ankle itch continued to provide pleasure even after the itch had been relieved. "The pleasurability of scratching the ankle appears to be longer lived compared to the other two sites," the researchers said.

"The present study uncovers a topographical relationship between itch attenuation by scratching and the accompanying pleasurability in healthy individuals," they concluded. "Future studies should also examine the scratching pleasurability associated with other itchy areas such as the scalp ...".

Why should itches and scratches be experienced differently on different parts of the body? Yosipovitch and his colleagues discussed a number of potential mechanisms, including differences in nerve density between body regions and regional variations in levels of neuropeptides known to be involved in itch induction. Prior research suggests the pleasure derived from scratching is associated with deactivation in brain areas - such as the anterior cingulate cortex - that are involved in the unpleasantness of itch, and the concomitant activation of other areas - such as the putamen - involved in the anticipation of reward.

How do these findings match your own experience? Do you find ankle itches particularly satisfying to scratch?
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  bin Saif, G., Papoiu, A., Banari, L., McGlone, F., Kwatra, S., Chan, Y., and Yosipovitch, G. (2012). The Pleasurability of Scratching an Itch: A Psychophysical and Topographical Assessment. British Journal of Dermatology DOI: 10.1111/j.1365-2133.2012.10826.x [h/t @mocost]. 

Post written by Christian Jarrett for the BPS Research Digest.

The stroke patient for whom strangers look normal whilst family look strange

Neuropsychologists in The Netherlands and the UK have documented the curious case of a 62-year-old stroke patient whose brain damage affected her perception of familiar faces whilst leaving her perception of unfamiliar faces intact

The woman, referred to as J.S., struggled to recognise family, fared slightly better with celebrities, whilst having no problems correctly categorising as unfamiliar the faces of complete strangers. When the woman's daughters came to visit her in hospital, she had no trouble recognising the daughter she hadn't seen for eight years, but struggled to identify her other daughter who visited daily.

Joost Heutink and his team confirmed this pattern of deficits by comparing J.S.'s performance against three age-matched women in a series of face recognition tasks. As well as having impaired recognition of her family (and to a lesser extent celebrities), J.S. also reported that the appearance of her family members was distorted. For example, she said her grandchildren looked grossly overweight and that they were a deep tanned colour. J.S. also had a general problem recognising emotional facial expressions.

Further details came from recordings of J.S.'s skin conductance (a measure of physiological arousal) when she looked at various faces. This showed that she experienced more arousal after looking at family members' faces as opposed to strangers and celebrities. This is normal, although the peak and latency of this arousal was delayed relative to the control participants.

So what explains J.S.'s pattern of deficits? Those familiar with neuropsychology may be reminded of Capgras Syndrome, in which the patient claims that one or more close relations have been replaced by an imposter. But J.S. does not have this syndrome. People with Capgras say that the imposter is a perfect likeness to the real relation. By contrast, J.S. does not think her relations are imposters, she just struggles to identify them and thinks their appearance has been distorted.

J.S.'s condition also bears some resemblance to prosopagnosia - a specific deficit affecting face recognition. Again, this doesn't really match J.S.'s neuropsychological profile. After all, her recognition of strangers' faces as unfamiliar was near perfect. Moreover, the brain region that's normally damaged in proposopagnosia - the fusiform face area - was unaffected in J.S.'s brain.

Joost Heutink and his colleagues think part of the answer may lie with a rare condition known as prosopometamorphopsia - in which other people's faces are perceived as being warped or distorted. The researchers suggest J.S. may have a form of this condition that interacts in some way with the emotional meaning of faces. So, if a face affects her emotionally (as happens with family), she perceives their face as distorted, which also has the side-effect of affecting her conscious recognition. This account fits with the distribution of brain damage in J.S.'s brain. In particular she suffered damage to the posterior superior temporal sulcus, which it's been suggested is involved in merging information about face identity with emotional context and meaning.

This account also helps explain two exceptions to J.S.'s relatively superior performance in recognising celebrity faces vs. family members. When it came to images of Hitler and Bin Laden (characters likely to trigger an emotional response), she believed they actually depicted imposters, and poor ones at that.

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Heutink, J., Brouwer, W., Kums, E., Young, A., and Bouma, A. (2012). When family looks strange and strangers look normal: A case of impaired face perception and recognition after stroke. Neurocase, 18 (1), 39-49 DOI: 10.1080/13554794.2010.547510

Post written by Christian Jarrett for the BPS Research Digest.

Could sportsmen and women benefit from "vision training"?

Researchers at the University of Cincinnati have reported dramatic improvements in their baseball team after enrolling the players in "vision training", designed to strengthen and speed the eye muscles and enhance visual processing. Based on their findings, Joseph Clark and his colleagues (including Hall of Fame catcher Johnny Bench) said "there are few sports that could not benefit from some form of vision training."

Thrice weekly 30-minute training sessions began six weeks prior to the 2011 season, becoming twice weekly during the season. There were eight different training exercises, which escalated in difficulty over time.

Here's a flavour of what was involved. With the "Brock string", balls were suspended on an 8-foot string extending from an athlete's nose, parallel to the ground. His task was to switch his focus from near balls to farther balls, thus training convergent movements of the eyes. Another exercise with strobe glasses had the effect of intermittently blinding the athlete as he tracked incoming balls ("the brain is forced to visualise where the pitch is going by processing the information it gets from the eye faster," the researchers said). The "rotary" task required that the athlete track letters and numbers that were spinning round at increasing speed (training smooth pursuit eye movements). The Dynavision exercise involved the athlete tapping targets as quickly as possible as they appeared on a large touch-screen.

Clark and his colleagues stressed that this was an observational study. They had no control group as such. To gauge the success of their training intervention they compared changes in their team's batting performance from the 2010 to 2011 season with changes recorded for other teams in the Big East league. The difference was striking. The batting average of the Cincinnati team showed a substantial improvement, whereas the average for all other teams actually deteriorated slightly, perhaps because of the introduction to the league of new aluminium bats designed to simulate wooden equipment.

The Cincinnati team's "slugging percentage" (a measure of batting power) also increased after the introduction of the vision training, whereas the slugging percentage of all other teams declined over the same period. "On-base percentage", another statistic related to batting performance, also improved in the Cincinnati team while falling in their rivals. The Cincinnati team's final league position was fourth for the 2011 season, up from seventh at the end of the prior season.

The researchers conceded that these batting improvements could in theory have had many causes, including maturation of existing players and the arrival of superior newcomers. However, they argued that there was no reason why these factors should improve performance for the Cincinnati team but not do so for any of their rivals.

"The muscles in the eyes can be trained and conditioned to perform better and faster in focusing and tracking objects such as baseballs," the researchers said - an idea they believe was corroborated by reports of eye muscle soreness among their players.

The time-frame for responding to a baseball pitch is so short, the researchers further explained, that the vision training likely provides batters with "a competitive edge ... a millisecond advantage." There was also some evidence of fielding improvements among the Cincinnati team and here the researchers speculated that "action on the field may appear slower and easier to follow for the vision trained athlete."

So, should other teams in baseball and related sports (the England cricket team, perhaps?) start their own vision training programmes, if they haven't already? Maybe not. These findings do imply that the vision training was beneficial, but there's no evidence here whatsoever that the benefits were mediated by improvements in visual function or enhanced eye movements. No data were presented for changes in the athletes' performance on the training tasks over time, and there was no analysis linking any such changes to the observed improvements in batting performances. For that reason, combined with the lack of a control group or control intervention, it's impossible to rule out the possibility that the observed benefits arose from anything other than a placebo effect.

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Clark, J., Ellis, J., Bench, J., Khoury, J., and Graman, P. (2012). High-Performance Vision Training Improves Batting Statistics for University of Cincinnati Baseball Players. PLoS ONE, 7 (1) DOI: 10.1371/journal.pone.0029109

Further reading. According to a 2008 Guardian report, the British Olympics Team employ the services of a vision training coach.

Post written by Christian Jarrett for the BPS Research Digest.