Scientists discover link between level of aggression and gait

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It has been suggested for years that the manner of a person’s walk correlates with certain personality traits. The lack of thorough empirical evidence and scientific analyses, however, left the hypothesis untested. The premise arose from studies on behavioral observation, a technique that is often deemed neither a quantitative nor a qualitative measure due to the need of coders, or trained specialists in research who employ a system in which they match up the results of an experiment to the parameters that have been set.

Previous studies regarding gait relied on the use of a coder. The use of a coder comes with obvious consequences, including the fact that human coders may not always be accurate in their results. A new study from the University of Portsmouth boasts results obtained by biomechanical measures, which aim to establish a concrete relationship between gait and personality traits.

In order to partake in the experiment, participants were asked to complete the Buss-Perry Aggression Questionnaire along with the Big Five Inventory. According to the study, “the Buss-Perry Aggression Questionnaire quantifies trait aggression into four subscales; tendencies to physical aggression and verbal aggression and dispositional anger and hostility towards others.” It is a tool normally used in order to calculate the level of aggression in an individual.

On the other hand, the Big Five Inventory typically measures varying levels of “conscientiousness, agreeableness, neuroticism, openness to experience and extraversion,” and is typically referred to as the most trustworthy and accurate basis for biometrics and trait analyses.

Participants were then asked to walk normally on a moving treadmill to find a speed at which they felt most comfortable. A single reflective marker was placed at the thorax and pelvis for all participants. The marker at the thorax measured the motion of the upper body while the one at the pelvis measured that of the lower body. The researchers also placed markers at various intervals along the arms and legs to measure gait more effectively. Motion capture systems were put in place to record and track any movement.

Prior to starting the treadmill and analyzing their walk, the researchers asked participants to stand up as they normally would in order to have a base of physiological measure. Then participants walked on the treadmill for a timed minute.

A three-dimensional model of both the thorax and pelvis of each participant was then created. The models allowed for the importation of customized computer data, which researchers inputted into the system in order to analyze the gaits cyclically within the minute. The researchers calculated the range of motion displayed by each gait cycle. In order to get a more accurate range of motion, the researchers found the average of the combined totals of each of the cycles.

There were no huge disparities between the 29 male and female participants, but the researchers chose to separate their data by sex for the sake of mild comparison. It was discovered that among female participants, aggression seemed like a prevalent characteristic, despite the fact that evidence of aggression in men was also present. Researchers found that both the motion of the thorax, in conjunction with the pelvis, dictated a more aggressive personality. If a particular gait showed the motion of either the thorax or pelvis, the person exhibited less signs of aggression in their personality. The greater the range of motion of both the thorax and the pelvis, the researchers found, the more aggressive a person will tend to be. The results of the analysis matched the answers the participants put down on the tests they were asked to complete in addition to the experiment.

The study indicates that “when walking, the body naturally rotates a little; as an individual steps forward with their left foot, the left side of the pelvis will move forward with the leg and the left shoulder will move back and the right shoulder forward to maintain balance. Put simply, an aggressive walk is one where this rotation is exaggerated.”

The researchers state in the discussion of the study that these findings could be particularly useful for police officers who are looking to catch potential suspects or committers of crime. However, certain ethical boundaries may arise out of these scenarios, in which people who intentionally alter their own gait to suit the atmosphere of the situation may be regarded as prime suspects by prejudice.

The researchers found that greater range of motion in a person’s thorax and pelvis correlates to a greater level of aggression.