Friday, May 18, 2012

New Insights into Emotion

This image is Jonathan Haidt's model for the conscious mind (the rider) and the unconscious mind (the elephant). He sees a serious power differential.

Two recent articles provide some new insights into the power of emotion in the human brain. In the first one, researchers have found that emotions can inhibit (essentially, shut down) higher cognitive functions without our being aware of it. This lends more credence to the recent series of books describing the dominance of the "fast brain" over the "slow brain" (Daniel Kahneman's distinction).

In the second study, researchers have found that emotional motivation is correlated with handedness, i.e, rather than being located in one specific part of the brain (such as language, which is a left hemisphere function regardless of handedness), "approach motivation is computed by the hemisphere that controls the right hand in right-handers, and by the hemisphere that controls the left hand in left-handers."

The first article is from Science Codex.

Psychologists reveal how emotion can shut down high-level mental processes without our knowledge

Posted On: May 8, 2012
Psychologists at Bangor University believe that they have glimpsed for the first time, a process that takes place deep within our unconscious brain, where primal reactions interact with higher mental processes. Writing in the Journal of Neuroscience (May 9, 2012 • 32(19):6485– 6489 • 6485), they identify a reaction to negative language inputs which shuts down unconscious processing.

For the last quarter of a century, psychologists have been aware of, and fascinated by the fact that our brain can process high-level information such as meaning outside consciousness. What the psychologists at Bangor University have discovered is the reverse- that our brain can unconsciously 'decide' to withhold information by preventing access to certain forms of knowledge.

The psychologists extrapolate this from their most recent findings working with bilingual people. Building on their previous discovery that bilinguals subconsciously access their first language when reading in their second language; the psychologists at the School of Psychology and Centre for Research on Bilingualism have now made the surprising discovery that our brain shuts down that same unconscious access to the native language when faced with a negative word such as war, discomfort, inconvenience, and unfortunate.

They believe that this provides the first proven insight to a hither-to unproven process in which our unconscious mind blocks information from our conscious mind or higher mental processes.

This finding breaks new ground in our understanding of the interaction between emotion and thought in the brain. Previous work on emotion and cognition has already shown that emotion affects basic brain functions such as attention, memory, vision and motor control, but never at such a high processing level as language and understanding.

Key to this is the understanding that people have a greater reaction to emotional words and phrases in their first language- which is why people speak to their infants and children in their first language despite living in a country which speaks another language and despite fluency in the second. It has been recognised for some time that anger, swearing or discussing intimate feelings has more power in a speaker's native language. In other words, emotional information lacks the same power in a second language as in a native language.

Dr Yan Jing Wu of the University's School of Psychology said: "We devised this experiment to unravel the unconscious interactions between the processing of emotional content and access to the native language system. We think we've identified, for the first time, the mechanism by which emotion controls fundamental thought processes outside consciousness.

"Perhaps this is a process that resembles the mental repression mechanism that people have theorised about but never previously located."

So why would the brain block access to the native language at an unconscious level?

Professor Guillaume Thierry explains: "We think this is a protective mechanism. We know that in trauma for example, people behave very differently. Surface conscious processes are modulated by a deeper emotional system in the brain. Perhaps this brain mechanism spontaneously minimises negative impact of disturbing emotional content on our thinking, to prevent causing anxiety or mental discomfort."

He continues: "We were extremely surprised by our finding. We were expecting to find modulation between the different words- and perhaps a heightened reaction to the emotional word - but what we found was the exact opposite to what we expected- a cancellation of the response to the negative words."

The psychologists made this discovery by asking English-speaking Chinese people whether word pairs were related in meaning. Some of the word pairs were related in their Chinese translations. Although not consciously acknowledging a relation, measurements of electrical activity in the brain revealed that the bilingual participants were unconsciously translating the words. However, uncannily, this activity was not observed when the English words had a negative meaning.

This article comes from Science Daily.

Emotion Reversed in Left-Handers' Brains

In right-handers, stronger approach motivational tendencies predicted more neural activity in the left hemisphere. In left-handers, the pattern was reversed. The significance of the interaction of Hemisphere with Approach Tendency is plotted separately for left-handers (blue) and right-handers (red). (Credit: Image courtesy of The New School)

ScienceDaily (May 2, 2012) — The way we use our hands may determine how emotions are organized in our brains, according to a recent study published in PLoS ONE by psychologists Geoffrey Brookshire and Daniel Casasanto of The New School for Social Research in New York.

Motivation, the drive to approach or withdraw from physical and social stimuli, is a basic building block of human emotion. For decades, scientists have believed that approach motivation is computed mainly in the left hemisphere of the brain, and withdraw motivation in the right hemisphere. Brookshire and Casasanto's study challenges this idea, showing that a well-established pattern of brain activity, found across dozens of studies in right-handers, completely reverses in left-handers.

The study used electroencepahlography (EEG) to compare activity in participants' right and left hemispheres during rest. After having their brain waves measured, participants completed a survey measuring their level of approach motivation, a core aspect of our personalities. In right-handers, stronger approach motivation was associated with greater activity in the left hemisphere than the right, consistent with previous studies. Left-handers showed the opposite pattern: approach motivation was associated with greater activity in the right hemisphere than the left.

A New Link Between Motor Action and Emotion
Most cognitive functions do not reverse with handedness. Language, for example, is mainly in the left hemisphere for the majority of right- and left-handers. However, these results were not unexpected.

"We predicted this hemispheric reversal because we observed that people tend to use different hands to perform approach- and avoidance-related actions," says Casasanto. Approach actions are often performed with the dominant hand, and avoidance actions with the non-dominant hand.

"Approach motivation is computed by the hemisphere that controls the right hand in right-handers, and by the hemisphere that controls the left hand in left-handers," says Casasanto. "We don't think this is a coincidence. Neural circuits for motivation may be functionally related to circuits that control hand actions -- emotion may be built upon neural circuits for action, in evolutionary or developmental time."

The authors caution that these data show a correlation between emotional motivation and motor control, and that further studies are needed to establish a causal link.

Implications for the treatment of depression and anxiety disorders
To treat depression and anxiety disorders, brain stimulation is used to increase neural activity in the patient's left hemisphere, long believed to the 'approach hemisphere." "Given what we show here," says Brookshire, "this treatment, which helps right-handers, may be detrimental to left-handers -- the exact opposite of what they need." The discovery that approach motivation reverses with handedness may lead to safer, more effective neural therapies for left-handers, according to Brookshire, "it's something we're investigating now."

Brookshire G, Casasanto D. (2012). Motivation and Motor Control: Hemispheric Specialization for Approach Motivation Reverses with Handedness. PLoS ONE 7(4): e36036. doi: 10.1371/journal.pone.0036036
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