What if arachnophobia could be overcome without the sufferer even realizing it? According to a study conducted by American researchers, ending one of our population’s most common phobias, a fear of spiders, could be achieved simply by exposing arachnophobes to subliminal images. Rather than putting them face-to-face with a tarantula, a subconscious exposure to photos might prove to be quite effective. How did the scientists make this surprising discovery?

Directed by Bradley S. Petersen (director of the Institute for the Developing Mind at Children's Hospital Los Angeles) and Paul Siegel (associate professor of psychology at NYU’s Purchase College), the team of researchers were attempting to study the neuronal basis for adaptation effects through exposure to subliminal images. They recruited 42 young female participants (M = 19.7 years) for their experiment, half of whom had a phobia of spiders. Why did they only select women? According to the authors of the study, published in Human Brain Mapping, previous research has shown that 75%-80% of arachnophobes are women. In addition to an interview and questionnaire, the subjects were given a behavioral avoidance test in which they were asked to gradually move closer to a (real) tarantula. Participants then viewed images in three conditions: viewing of control images (flowers) that were unrelated to the phobia, and viewing of images related to the phobia (spiders) at two different exposure durations: very brief (33.4 ms – insufficient for conscious awareness of what is being viewed) and longer exposure (117 ms - long enough for the image to be clearly identified). Throughout the experiment, the researchers observed the women's brain activity using a functional MRI. What did they observe?

In arachnophobic participants, exposure to subliminal images (very short exposure times) of spiders strongly activated the areas of the brain involved in immediate fear processing (which is to be expected), but it also activated those areas that regulate reactions to fear (behavior, emotions, etc.): in particular the frontal cortex and caudate nucleus. This means that these young women were afraid… but didn’t realize it! Conversely, when these same participants had ample time to view the spider images, they consciously experienced fear. However, their frontal cortex and caudate nucleus were actually less active than in the brief exposure condition, meaning they were less able to control their fear. Thus, the subliminal images of spiders could allow the brain to “regulate” the phobia.

In conclusion Paul Siegel explains that, “Counter-intuitively, our study showed that the brain is better able to process feared stimuli when they are presented without conscious awareness.” According to Siegel, “Our findings suggest that phobic people may be better prepared to face their fears if at first they are not consciously aware that they’ve faced them.” An interesting possibility for developing therapies to treat anxiety disorders!