How Facial Expression And Muscle Response Is Emulated By Activity In The Brain And How To Identify It

Emotions felt by the brain are always expressed by the muscles in the face, even when a person tries to remain neutral. Emotions are objective as are facial expression, this applies to every person, regardless of race, gender or ethnicity. The human face contains 32 muscles, 16 on each half of the face. 16 of these 32 muscles contract voluntarily, the other 16 are controlled involuntarily by the neostriatum, amygalada, orbitofrontal cortex and insular cortex (Gorno-Tempini, et al., 2001). This study by Gorno-Tempini was conducted by having subjects make decisions about face gender when exposed to different facial expressions. Images of seven different facial expressions were screened and a FMRI machine was used to detect the brain activity when the subjects processed these facial expressions. Upon seeing these neutral, happy or disgusted faces, the subjects showed varied levels of activities at different parts of the brain. This study proves the link between facial expression and brain activity. These expressions last under a second, just as their respective brain activity lasts under a second. These are known as micro expressions. There are seven universal micro expressions that are expressed by every person anger, fear, sadness, disgust, contempt, surprise and happiness (Darwin, et al., 1998). The application of understanding micro expression is used in clinical psychology and is used for deception analysis, understanding if a person is telling the truth or not based on their facial expression (Porter and Ten Brinke, 2008)

Seven universal micro expressions are shown through specific contractions of muscles in the human face. A genuine expression is shown through the innate muscle contractions, whereas an emulated facial expression shows visible differences, this can be used to detect lies if a person s facial expression does not match what they are saying (Porter and Brinke, 2008). It is commonly known that a genuine smile shows muscle contractions at the Levator labii superioris, Orbicularis oculi, Levator anguli oris and Orbicularis oris (Ekman, 2006). These are the muscles around the eyes, cheeks, lips and corners of the lips. The Orbicularis oculi makes a contraction when the bilateral orbitofrontal cortex is showing activity, this is the micro expression associated with happiness, amusement or excitement. Disgust is shown by a distinct, upward contraction of the Buccinator and a downward contraction of the Nasalis (Ekman, 2006). This is shown by a scowl scowls are a universal expression of disgust and distaste towards a stimulus (Ekman, 2006). Clearly visual expressions are Macro expressions. They last longer than a second, whereas micro expressions last less than a second. Identifying these micro expressions determines a person s emotion. A study by Porter and Brinke in 2008 showed that 100% of participants in the investigation showed emotional leakage in the form of micro expressions or macro expressions at least once in a 10 minute conversation. A conversation was recorded, then played back at a slower speed in order to identify the exact muscle contractions in the upper and lower face. It was found that 21.95% of participants showed micro expressions that did not concur with what they said. This study therefore shows that micro expressions are able to identify lies. These techniques are used in clinical psychology to determine if a patient is lying or not, if a micro expression is showing an emotion that contradicts what the patient is saying, then the patient is lying. (Porter and Brinke, 2008 Ekman, 2009)

Different parts of the brain show activity when a person is feeling an emotion, concurrently a micro expression or a macro expression is shown. A study evaluated the brain activity of subjects when shown images of people expressing different facial expressions. This study by Gorno-Tempini in 2001 using an FMRI machine found that the left inferior frontal cortex as well as the bilateral occipito-temporal junction showed activity when responding to any and all present face conditions (Gorno-Tempini, et al., 2001). This study therefore found that these parts of the brain are used for the processing of faces and always show activity when looking at a human face. Furthermore, the right neostriatum as well as the left amygdala showed activity when responding to faces that showed disgust (Gorno-Tempini, et al., 2001). This study therefore proves that reactions to negative emotions results in the experience of negative emotions by a person. Darwin explains this in 1998 in his book when responding to disgust a person is most likely to respond with shame or fear (Darwin, et al., 1998). The bilateral orbitofrontal cortex was activated when a subject responded to faces that showed happiness(Gorno-Tempini, et al., 2001). This proves that the bilateral orbitofrontal cortex is responsible for decision making and judgement, when responding to positive emotion such as laughing and smiling, the orbitofrontal cortex is showing activity. This causes a person to feel empathy and makes the person respond with positive emotion. People with autism have a lower level of activity in the inferior frontal cortex and bilateral occipito-temporal junction (Grice, et al., 2001), which reduces an Autistic person s social skills and ability to determine facial expression, in addition, the orbitofrontal cortex shows less activity thus preventing an autistic person from responding to emotion with emotion of their own. A study by Grice in 2001 used ECG to show that normal adults show ECG bursts at 40 Hz for cognitive reasoning, such as recognising faces, however Autistic people do not show this ECG burst, proving there is a lower activity in the brainwhen reading faces. This evidence shows that both cortial and subcortial structures are used in processing and understanding facial expression (Gorno-Tempini, et al., 2001 Grice, et al., 2001).

Identifying facial expression is done accurately by using a camera that detects movement. This has been proven effective for broad investigations in police work as well as clinical diagnosis. (Yan, et al., 2014). A study from Wen-Jin Yan in 2014 has shown that the CASME II database of micro expressions is used to match a person s face to a database of specific muscle contractions by using a DSLR lens camera with a high resolution (2048 x 2048 pixels) and frame rate (120 frames per second). This is able to determine what a person is feeling during an interview, interrogation or deposition, and if they are telling the truth or not. The clinical advancements of micro expression training and the use of CASME II have led researchers to identifying psychopathic behaviour (Wai and Tiliopoulos, 2012 Yan et al., 2014). Psychopaths express the same facial expressions as normal people. Psychopaths express less empathy than the average person (Wai and Tiliopoulos, 2012). As a result, a psychopath does not express an expected emotional response to a stimulus. This appears as if the psychopath is lying, and is the reason for why psychopaths are more likely to appear honest during a polygraph test. This error in polygraph testing can be eliminated through the use of the CASEME II database, as it can account for psychopaths whereas the polygraph cannot. This method makes micro expression detection accurate and precise.

In Conclusion, understanding the link between facial expression and brain activity through micro expressions is critical for clinical diagnosis and treatment as well as national security. Micro expression reading is used for deception analysis and is vital to national security. A social environment can be manipulated by responding to an individual s emotion and changing it. The muscles in the face are directly controlled by cortial and subcortial structures of the brain. Applications of using micro expression training are used in deception analysis and autismtreatment. Alternative applications include understanding animal behaviour and using a non-verbal method to communicate and understand other mammals. Abnormalities in brain activity when reacting to a stimulus is used to diagnose mental disorder when reacting to a neutral face, a person with PTST will react with more activity in the amygalada, with a constant fight or flight response. Diagnosis of this is visible fear micro expressions and contraction of the masseter. This is be diagnosed quickly and accurately through micro expression training, and a subsequent treatment is put into action. Future applications of micro expression detection are developing an accurate camera that can identify micro expressions and confirm them using the CASME II Database. By knowing what a person is expressing through what they say, it is possible to know if they are telling the truth.

References and Citations

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