Month: January 2005

Beatriz Calvo-Merino and researchers from University College London have been investigating how the brain understands other people’s movements with the help of professional ballet dancers and experts in capoeira.

It is thought that the human brain has a ‘mirror system’, that simulates the actions of others as we observe them. This might be the basis of a number of important skills such as observational learning and communication.

This system seems particularly tuned to biological motion, as it doesn’t seem to activate when mechanical motion is viewed, or, for example, when an obviously artificial hand is watched while it moves.

Calvo-Merino used the brain scanning technique fMRI to investigate whether the mirror system of expert dancers would react differently when watching their own dance style, when compared to a dance style they didn’t know.

They found that when dancers viewed moves which they were expert in, their brains were more active in areas associated with action planning, body image, motion perception and, unexpectedly, and reward and social behaviour.

The results suggest that the mirror system is involved in understanding the movement of others by combining it with our own repertoire of skills and experience, and that this may be a crucial part of our social interaction.

Link to story from sciencedaily.com
Link to the abstract of the study from the journal Cerebral Cortex.

Here’s another story related to Vaughan’s post of a couple of days ago about the amygdala and fear perception.

A brain imaging study reported in the journal Science [1] found that showing the silhouettes of fearful eyes for just 17 milliseconds was enough to increase activity in the amygdala’s of human subjects – the effect is something like just seeing the whites of someone’s eyes in the dark (as shown in the picture, along with the comparison condition – the silhouette of the eyes of someone showing a happy expression).

The two things struck me about this. The first, obviously, is how brief the exposure is. If you are shown something for 17ms you will probably be unable to tell that you’ve been shown anything at all (you might see a flash), you certainly won’t be able to tell what it is. In this study the 17ms picture of eyes was immediately followed by a picture of a normal, expressionless, face – which makes perceiving the eye-silhouettes even harder (and, indeed, none of the participants in the experiment reported that they noticed anything unusual).

But their brains did. The amygdala was already ramping up, ready to signal ‘be afraid’ to the rest of the brain. And this to something that isn’t actually scary in itself – but a social signal that there is something to be afraid of nearby. Social and emotional information is being priority-routed through the brain’s processing streams.

Continue reading “Eyes wide with fear”

Neuroscientist Ralph Adolphs has been working with a woman known only by the initials SM. She has damage to the amygdala on both sides of the brain, and although she can recognise emotions such as happiness, anger, surpise, sadness and disgust on people’s faces, she can’t recognise fear.

Adolphs investigated exactly what SM was looking at when she viewed emotional expressions and found that she rarely looked at the eyes. Most other emotional expressions can be recognised from other parts of the face, but recognising fear seems to particularly involve viewing the eyes.

When prompted to look specifically at the eyes, SM became a lot better at recognising fear, although quickly reverted back to avoiding them if not reminded.

The amygdala has been traditionally associated with emotion, particularly the negative emotions, but Adolphs suggest that maybe it has a wider function, also involving visual attention and analysis.

Why damage to the amygdala might specifically cause problems with viewing the eyes of other people remains to be investigated, as does whether SM’s ability to focus in on other parts of the face is entirely normal.

Link to story on nature.com

Researchers from the Universities of Queensland and Denver have found that newborn babies preferentially look at human faces, but not human body shapes in general. This seems to suggest that face recognition might be innate in some way and might be one aspect of our genetic inheritance which promotes social interaction and allows us to develop subtle social communication skills needed for the complexity of human interaction.

A study published in 2004 suggested that this is more than just a simple preference for any face-like shape, but that newborn babies prefer attractive rather than unattractive faces. It is still unclear why this might happen, although it perhaps hints that attractive faces may seem more attractive because they more closely match a configuration passed down to us via our genes.

The excuse “Sorry honey, I was just looking to see if their face matched my genetic template of innate face shapes” is of course unlikely to get you out of trouble, regardless of your ability to describe the science behind it.