Anxious individuals are commonly characterized as being easily threatened and more sensitive than their counterparts. But a new study measuring brain activity challenges this perception as researchers found anxious individuals may not be sensitive enough.
Researchers from Tel Aviv University used an electroencephalograph (EEG) to measure brain activity as study participants were shown images designed to induce fear and anxiety.
EEG recordings of the neuronal activity that represents deep processing of these stimuli showed that the anxious group was actually less stimulated by the images than the non-anxious group.
The results of the study were recently published in Biological Psychology.
The discovery that anxious study participants weren’t shown to be as physiologically sensitive to subtle changes in their environment as less fearful individuals, surprised the investigators, says Tahl Frenkel, a doctoral candidate and study leader.
She suggested that anxious people could have a deficit in their threat evaluation capabilities — necessary for effective decision-making and fear regulation — leading to an under-reaction to subtle threatening stimuli.
Non-anxious individuals seem to have a subconscious “early warning system,” allowing them to prepare for evolving threats. Essentially, anxious people are “surprised” by fearful stimuli that non-anxious individuals have already subconsciously noticed, analyzed, and evaluated.
For a more detailed analysis of both behavioral and neural reactions to fear-inducing stimuli, the researchers drew participants from a group of 240 undergraduate students at the university. Investigators then identified the 10 percent “most anxious” individuals and 10 percent “least anxious” individuals to participate in the final study.
In the first part of their study, the researchers measured behavioral responses to fear-inducing stimuli. A set of pictures, featuring a person looking progressively more fearful on a scale of 1-100, was shown to the participants.
When shown the sequence of pictures, anxious people were quicker to respond to the fear in the subject’s face. They identified a face as being “fearful” at a rating of only 32, while non-anxious people did not describe the same face as fearful until it reached a rating of 39.
However, when the investigators measured the participants’ brain waves by EEG while they were being shown the photographs, a different picture began to emerge.
From this assessment, researchers discovered that non-anxious individuals completed an in-depth processing of fear-inducing stimuli that informed their behavioral response, whereas anxious individuals did not.
In other words, non-anxious individuals were able to unconsciously notice subtle changes in the environment before they consciously recognize the threat.
“The EEG results tell us that what looks like hypersensitivity on a behavioral level is in fact the anxious person’s attempt to compensate for a deficit in the sensitivity of their perception,” she explains.